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2nd B.sc.,

The Power of Completeness…….

Prepared by

NICE COMPUTERS

NICE COMPUTERS No.1 in Kavali

OOPS with Java and DS 2

UNIT – 1 1. Write about the object oriented paradigm? The major objective of object oriented paradigm is to overcome the drawbacks of procedural paradigm. Object oriented paradigm treats the data as an important element in the program development, does not allow to directly access from the program and unauthorized users. Functions called methods are used to access, modify and store the data. Combination of data and methods are called objects. Object Oriented Paradigm allows decomposing the problem into number of entities called objects. Definition: Object Oriented Programming is an approach that provides a way of modularizing programs by creating partitioned memory area for both data and functions that can be used as templates for creating copies of such modules on demand. Features of object oriented paradigm: Object Oriented Paradigm has the following important features. Emphasis is given to the data rather procedure Program is divided into number of objects. Data cannot be accessed either by the program or by the unauthorized

users Methods are used as interface among the data and program Objects communicate through methods Follows bottom to top approach

Method

Method

Method Method

Name Sal

Void setData() { ---------- } Void getData() { ----------- }



2. Write about the object oriented programming features? (Or) Write about the concepts of Object Oriented Programming? Definition: Object Oriented Programming is an approach that provides a way of modularizing programs by creating partitioned memory area for both data and functions that can be used as templates for creating copies of such modules on demand. Like any object oriented programming language, even java supports the following object oriented programming concepts. 1. Data Abstraction or Encapsulation 2. Inheritance 3. Polymorphism 4. Dynamic binding 5. Message Communication Data Abstraction and Encapsulation: It is the striking feature of a class. Wrapping up of data and methods as single unit in the class is known as Encapsulation. Data is stored in the center of an object. This cannot be directly accessed from the program. Methods are wrapped around the data. These work as interface among the program and data. The insulation of data from direct access from the program is called Data Hiding or protection. Abstraction is representing essential features without giving the background details. It separates the Usage from implementation. Inheritance: It is an important feature o any object oriented programming language. It supports the concept of hierarchical classification. Inheritance is the process of reusing the properties of existed class rather re-defining all over again. Inheritance is mostly used to enhance or modify the existed class definition. Here the existed class is called the super class and the new extended class is called sub class. The sub class has the members of both super and sub classes.

Bird

Flying Bird Non-Flying Bird

Robin Swallow Penguin Kiwi



Polymorphism: Polymorphism is another important feature. The meaning of polymorphism is many forms. That is the ability to take more than one forms. For example operator + is used on two purposes one is to add any two numbers and to concatenate any two strings. Another example to polymorphism is method overloading. That is selecting a method from multiple methods of the same name and unique signature. Selection of method depends on the number and type of arguments send to the method. Dynamic binding: Binding is selection of method in response to the call. If it done during the runtime then it is called dynamic binding or run time polymorphism. For example Interface shape has draw() method. It is overridden in different implementing classes like Circle, Box and Triangle. The reference of shape interface calls draw() method of any class according the object to which it refers. Message Communication: The process of programming in object oriented language involves 1. Creating classes 2. Creating objects belongs to the classes 3. Establishing communication among the objects. Objects communicate by sending or receiving the message by calling the method of one object from another object like the way people pass the message called message passing.

Shape

draw()

Circle Object

draw()

Box Object

draw()

Triangle Object

draw()

Ob.setName(“Balagurusami”);

Object Method Information



3. Write about the benefits of OOP? OOP offers number of benefits to both the designer and the user. Object orientation contributes to the solutions of many problems like Development, Quality maintenance, less maintenance cost and productivity. The advantages of OOP are We can eliminate the redundant code through inheritance. We can use the existed code modules. This leads to reduce of

development time and improves the productivity Data hiding helps to develop secured applications It is possible to have multiple members with the same name in different

objects (Encapsulation) It is easy to partition the work in a project through objects. It is easy to update an existed system Software complexity can be easily managed Though it is possible to use all these benefits in any object oriented application, any or all of these features are used according to the project. 4. Write about the applications of OOP? The most popular applications of OOP are in the areas of user interface design for windows. OOP simplify the development o complex applications due to their unique features. The areas of OOP applications are. 1. Real-time systems 2. Simulation and modeling 3. Object-Oriented databases 4. Hypertext, hypermedia and expertext 5. Artificial Intelligence and expert systems 6. Neural networks and parallel programming 7. Decision support and office automation systems 8. CIM/CAD/CAM systems 5. Write about the features of java? The inventors of java designed the java so that it could offer solutions to the problems encountered in modern programming. Sun microsystems officially describe the java as. 1. compiled and interpreted 2. Platform independent and portable 3. Object Oriented 4. Robust and secure 5. Distributed 6. Familiar, simple and small



7. Multithreaded and interactive 8. High performance 9. Dynamic and extensible Compiled and interpreted: Execution of a java program is done in two steps. That is compiling and interpreting. First the source code is compiled by the java compiler (javac), produces the byte code. Byte code is not the executable code which cannot be executed. The java interpreter (java) generated the machine code, which will be executed by the computer. So java is called both compiled and interpreted. Platform independent and portable: Java application developed on one platform can be easily moved and used on another platform without any modifications. Here the platform difference is the difference in operating system or in architecture. Internet is a network of networks with millions of computers belongs to different platforms. Hence java became a popular language to develop internet applications. Object Oriented: Java supports all the common object orient programming features like Data hiding, Abstraction, Inheritance, Encapsulation and inheritance Robust and Secured: Security is an important issue for a language which is used to develop internet applications. Byte code verifier of JVM ensures that no virus is communicated with applets. In absence of pointers java application cannot access unauthorized memory. Distributed: Java provides some of the concepts like RMI, Networking and Servlets. Which help to develop distributed applications like intranet and internet applications. Simple, Small and familiar: Java is a simple and small language. Most of the features of C and C++ are added in java. Java does not support unsafe features like pointers, preprocessor statement, goto, operator overloading and multiple inheritance. Java uses many constructs of C and C++. Hence java code looks like C and C++ code. Multithreaded and interactive: Multithreading is the natural feature of java. It allows performing multiple tasks at a time through a single java application.



High Performance: Execution of byte code or intermediate code is much faster than the native code of C and C++ Dynamic and Extensible: Java is capable of loading classes from the library dynamically. Java supports of using functions belong to other languages called native methods. 6. State the differences among java and C, C++? Differences among java and C: Lot many things are common in C and Java. Java is an object Oriented programming language. Some of the features of C language are not added due to the security reasons. 1. Java does not support the keywords goto, sizeof, typedef 2. Java does not support the data types like enum, struct and union 3. Java does not support the type modifiers auto, extern, register, unsigned 4. Java does not support pointers. 5. Java does not support pre-processor directives 6. Java has two operators >>>, <<< (Shift assigning) and instanceof

operator 7. Java has labeled break and continue 8. Java supports all the common object oriented programming features Differences among java and C++ Java is a pure object oriented programming language. Where as C++ is an extension to C. C++ supports both procedural and object oriented programming. The following are the differences among C++ and Java

1. Java does not support operator overloading 2. Java does not support multiple inheritance using classes 3. Global variables cannot be declared in java. Every variable must be a

member of any class 4. Java has no Destructors

C++

C Java



7. Write how java associated with WWW (World Wide Web)? Java and Internet: Java is strongly associated with internet. “Hot java” is the web browser developed in java. Applets are the small java programs add dynamism to the web pages. Applets are associated with the web pages. These are downloaded along with the web pages, executed by any java enabled web browser. Java and WWW (World Wide Web): World Wide Web is a homogeneous network of networks, connected with millions of computers around the globe. It is an information retrieval system. This system contains web sites belongs to different organizations. Collection of web pages is called a web site. These web pages are developed in HTML. Hyper links are used to navigate among the web pages. Because HTML is a tag based formatting language. Only static web pages can be developed. Applets are the small java programs used to develop interactive web pages. Java helped to develop web pages with animations, graphics, games and special effects. Applet is a small java program developed and compiled byte code of which is stored in the web server. <Applet> tag is used to bind an applet with HTML page. How an applet is executed:

1. User sends the request to the web server; In return the web server sends the requested document to the client.

2. As specified in the <Applet> tag the byte code is down loaded in to the local machine

3. The JIT (Just in Time) interprets the byte code and produces the managed executable code.

4. The executable code is executed by the java enables web browser

Server Client

1

1 Applet Source Code

Byte Code

<Applet> HTML

Document

HTML Document

2

Web Browser 3

Output

4

JIT



8. Write about the Web Browsers? Internet is a heterogeneous network of network. It is with the vast information of different formats. Web browser is client-side software used to download and execute the web pages developed in HTML. Web browser has tools to navigate among different web pages, mailer to send and receive the e-mails etc. There are different web browsers available to browse the internet. 1. Hot java: It is the first java enabled web browser, developed entirely using java platform. It is the first web browser executed java applets. It is developed by “Sun micro systems”. Now, hot java web browser is available for Solaris, Windows 95 and Windows NT. 2. Netscape Navigator: It is one of the most widely used web browsers today. It is developed by Netscape communications. It is a general purpose browser executes applets also. Now, Netscape navigator is available for Windows, Solaris and Macintosh. It also supports scripting languages. 3. Internet Explorer: It is the most widely used web browser available freely with the windows. It is a general purpose browser executes applets also. It also supports different scripting languages. Internet Explorer uses JIT to execute the applets. 9. Write about the java environment? Java environment includes number of development tools and number of classes and interfaces. JDK (Java Development Kit) Number of tools used to develop and test any java application is a part of JDK called java development kit. There are different versions of JDK available in market. Latest version of JDK is JSDK1.6.0. (Java Software Development Kit). JDK includes Javac (Java Compiler) Java (Java Interpreter) Appletviewer (To develop and test applets) Javap (Java Dis-assebmbler) Javadoc (To create documentation automatically) Jdb (Java Debugger)



Java API (Application Program Interface) JDK provides a library of classes, interfaces and constants to develop any java application. These resources are managed as packages and sub packages. Java.lang: Collection of classes to implement basic java features. Java.util: Collection of utility classes to calculate Date and Time operations. Java.io: Collection of classes to perform basic Console, File input and output. Java.net: Collection of classes to perform connections among different computers. Java.awt: Collection of classes and interfaces to develop window applications. Java.applet: collection of classes to develop web based small java programs called applets. 10. Write about the structure of a java program? Any java program has class definitions, import statements and class hierarchies. Stand alone programs and applets: Any java program has one or more class definitions. A class definition has different members. These members include data fields, methods and classes. Any java application can be divided into stand-alone applications and applets. Any stand-alone application executes from the main() method. Where as applets execute from the init() method. An applet is a java application embedded in a HTML document. Packages: Re-usability is the primary feature of any language. Java supports reusability by means of packages and inheritance. Package is a

Document Section

Package Statement

Import Statement

Interface Statements

Class Definitions

Main Method class



collection of re-usable classes. Where package is a folder and classes are files in the folder. JDK(Java Development Kit) provides a hierarchy of classes called java API. These classes can be imported into any java program using import statement. “java” is the root package in JDK. It has other packages with different category of classes. Example: Java.io // Defines number of input and output classes. Java.util //Defines number of utility classes. Importing classes and packages: Import is the statement used to import a class or all the classes of a package. Specifying only the class name imports a single class. Specifying * imports all the classes of a package. Example: Import java.util.Date; // It imports only the Date class. Import java.util.*; //It imports all the classes of util package. Sub classes and super classes : Because java is an object oriented programming language, it supports hierarchical relationship among the classes. Suppose A and B are two classes and there is a line or edge between two, then the class A which is at the higher hierarchy is called super class. Class B which derives from A is called a sub class. Java supports simple, multi-level, hierarchical and hybrid inheritance but not multi-level inheritance. Example: 9. Write about the JVM (Java Virtual Machine)? (Or) Write how to implement a java program? (Or) Write how to execute a java program? (Or) How java works like an object Oriented Programming Language?

Object

Number String Trowable

Integer Double Exception Error



In case of “c” and “c++” languages the compilation process translates the source code into native language of computer. The native code generated by one computer may not work on another computer called platform dependency. Implementing a java program: While executing a java program the source code is compiled by the java compiler (javac) first. The java compiler produces the byte code. It is more compact and efficient than the executable code generated by “c” and c++ programs. The byte code is native language to the JVM (Java Virtual Machine). The java interpreter (java) of JVM executes the byte code. Since every computer supports JVM, byte code can be executed by any computer. So java is called platform independent language. Since java programs run in native mode, they run 100 times slower than the c and c++ programs. But java has lot of advantages comparatively with c and c++.

1. Java byte code runs on any computer that supports JVM. 2. Java byte code is compact than native code of c and c++. 3. JVM provides additional security by checking the foreign code using

byte code verifier. JIT (Just in time) is a compiler installed at the client. It loads and compiles the byte code by downloading from the server. Java microprocessor is another tool which translates the byte code into native code. It improves the performance of java application even better than a c and c++ application. It improves the performance of java application even better than a “C” and “C++” application.

Source Code (hello.java)

Java compiler (Javac)

Byte Code (hello.class)

JVM Computer (HWR)

Remote JVM

Remote Computer (HWR)



JVM (Java Virtual Machine): It behaves like a computer within computer. So it is called JVM. It is with the combination of class loader, byte code verifier and java interpreter (java). The class loader loads the remote classes in to the local memory. The byte verifier allows only byte code to the interpreter. The java interpreter produces the native code to the machine. Execution of a java program: A java program can be implemented in three steps. 1. Developing the program 2. Compiling the program 3. Interpreting the program Step1: A java program can be developed in any text editor. It is saved with .java extension. Step2: java program is compiled with the java compiler(javac). Step3: The byte code generated by the compiler is executed by the java

Source Code (hello.java)

Compiler (javac)

Byte Code (hello.class)

Class Loader

Byte Code Verifier

JIT/Java Micro Processor

Java Interpreter (java)

Computer HWR

JVM

class Hello { public static void main(String args[]) { System.out.println(“Hello world”); } }

>Javac Hello.java



interpreter 10. Write about the Command line arguments? Sending arguments from the command line to the main method of the program, while executing the program is called command line arguments. When we send command line arguments to the main() method while interpreting the program, the JVM creates an array of strings with the arguments and send to the main. Through the reference of array of strings we can access the arguments into the main. It helps to improve the flexibility in application development. Example: Individual elements of command line arguments are accessed from the main using the index of args[] 11. Write about the tokens in java? Smallest part of any java program is called java tokens. According to their functionality java tokens can be classified into

1. Keywords 2. Identifiers 3. Constants or literals 4. Operators 5. Separators

>java Hello

>javac Demo.java >java Demo hello I am the learner Class Demo { Public static void main(String args[]) { for(int i=0;i<args.length;i++) System.out.print(args[i]+” “); } }

Hello I am the learner

O/p Hello I am The learner



Keywords: These are the reserved words in java. Each keyword has a specific purpose in java. There are totally 60 keywords used in java. All the keywords must be written in lower case. Because java is a case-sensitive language. Out of these keywords const and goto have no functionality. Identifiers: These are the words used for naming the variables, arrays, classes, interfaces, methods and classes. The following rules must be followed while selecting proper identifier. 1. These may be of any length 2. Reserved words cannot be used 3. First character must not be a digit or special symbol 4. Special symbols cannot be used other than _(underscore) Identifiers must be meaning full, short, easily typed and self descriptive. The following naming conventions are used in java. Class name must be in capitalized format When more than one word are used in a name then, the second and

subsequent words must be capitalized All the data fields must be in small case All the constants must be in capital case Constants or literals: These are the values stored in the computer memory. These may be classified into Integer constants Floating point constants Character Constants String constants Boolean constants Operators: Different operators are used to write expressions in java. These operators can be classified into arithmetic, relational, logical, increment decrement, short-cut, conditional and bitwise operators. Separators: These are the symbols used to indicate group of code divided. () , ; {} [] . are some of the separators.



12. Write about the statements in java? A statement is an executable combination of tokens terminated with a semicolon. Statements are executed in a sequence as they appear. The total statements in java can be classified into 1. Empty statements 2. Labeled statements 3. Expression statements 4. Selection statements 5. Iterative statements 6. Jump statements 7. Synchronizing statements 8. Guarding statements 13. Write about the constants used in Java? These are the values stored in the computer memory. The values of which do not change during execution of program. These constants can be classified into

Constants

Numeric

Integer

Decimal Ex: 345, -897, 0

Octal Ex: 0345

Hexadecimal Ex: 0X97A67

Real Constant

Fixed Ex: 12.45, -45.89, 0 Scientific Ex: 12E-5

Character Single Character Ex: ‘x’, ‘P’, ‘;’

String Ex: “nice”, “Nice”

Back slash character Ex: \n, \t, \b, \0, \’, \”, \\



14. What is variable? (Or) Declaration of variable? (Or) Assigning values to the variables? Variable: A variable is an identifier represents a storage location to store a value. Its value changes during the execution of the program. The name of the variable must be a valid identifier. The following rules must be followed while selecting proper identifier.

a. These may be of any length b. Reserved words cannot be used c. First character must not be a digit or special symbol d. Special symbols cannot be used other than _(underscore)

Identifiers must be meaning full, short, easily typed and self descriptive. The following naming conventions are used in java. Ex: length, breadth, area, peri Declaration: Declaration of variable allocates the memory allocation in the primary memory. Declaration of variable does three things.

1. It tells the compiler the name of variable 2. It specifies the type of data which going to be stored 3. The place of declaration decides the scope of variable

Assigning values: A value can be assigned to the variable after its declaration. Values can be assigned to the variables in two ways.

1. By using an assigning statement. 2. By using a read statement.

Assigning: Syntax: Variable Name = Value Example: int x=40; float y=12.56; char z; z=’p’; Read statement: Syntax: variable name = (Reading statement) String name=(new Scanner(System.in)).nextLine(); //To read a line int y=(new Scanner(System.in)).nextInt(); //To read integer float x=(new Scanner(System.in)).nextFloat(); //To read Float



15. Write about the data types used in java? Java supports different data types to allocate the memory to store different constants of different types and ranges. These types can be classified into. 16. Write about the scope of variables? Variables in java can be classified into three types

Instance variables Class variables Local variables Block variables

Instance variables are the non-static data fields of a class. Memory allocation of these data fields happen on creating an object belongs to the class. The variables hold different values to different objects. Class variables are the static data fields. These are global to the total class and its objects. These data fields are used to store welfare data to all the objects and constants.

Floating point

Float 4bytes Double 8 bytes

Numeric

Byte 1Byte Short 2 bytes Int 4 bytes Long 8 bytes

Integer

Data types

Primitive

Non-Numeric Char 2 bytes

Boolean 2 bytes

Non - Primitive

Class

Arrays

Interface



Local variables are the variables declared with in a method. The scope of these variables is limited to the method in which they are defined. Block variables are variables defined within a block {} associated with any of the control structures. The scope of these variables is limited to the block. 17. Write about the symbolic constants? Symbolic constants are the constants appear repeatedly in a number of places with in the program. While using these constants we face two problems, that is

1. problem in modification of program 2. problem in understanding the program

Modifiability: Whenever we need to change value of constant, then we need to search and modify wherever it has been used. Otherwise the program may give unexpected result. Understandability: Proper names must be used to improve the readability. Different constants are defined with different names though they are assigned with the same values. Syntax: Final type Constant = value Example: class Constants { final int PASS_MARK=100; final float PI=3.4; }; The following rules must be followed while defining symbolic constants

1. These must be written in capitals 2. The values cannot be changed once they are assigned with values 3. These are declared for types. But not like #define statements in C and

C++ 4. These must be defined as class members only

18. Write about the type casting in java? Some times in an assigning statement, the type of expression may be different from type of assigning statement. In such case expression type must be changed to variable type.



Auto casting: Some times expression type is automatically converted into variable type called auto casting or implicit casting. In java the lower types will be automatically converted to higher types. Examples: Short x=45; Int y=x; Int x=25; Float y=x+22; Type casting: Some times expression type must be explicitly converted to variable type using typecast operator. It is an instruction to the compiler. In an expression an integer constant is considered as “int” type. In any assigning statement a real constant is considered as float type. Syntax: Variable = (Variable type) Expression Examples: Float x = (float) 5/2; Byte x=20; Short y = (short) x+10; Float x = (float) 12.25; Float y=12.25f; Note: Boolean type cannot be converted into any other type.

Byte short Byte, short int Byte, short, int long Float double Byte, short, int float Byte, short, int, float double



UNIT II 1. Write about the operators used in java? Java is rich in operators. These operators are used to write expressions. These are used to manipulate data and variables. These operators are classified as

1. Arithmetic operators 2. Relational operators 3. Logical operators 4. Assigning operator 5. Increment and decrement operator 6. conditional operator 7. bitwise operator 8. special operator

1. Arithmetic operators: +, -, *, /, % are the arithmetic operators. These work same as in other languages. These work on all primitive types other than Boolean type. The unary minus multiplies the operand by -1. Integer Arithmetic: When all the operands in an arithmetic expression are of integer type then the expression is called an integer expression. All ways an integer expression returns an integer value. Example: 5/2 return 2 Real Arithmetic: When all the operands in an arithmetic expression are of floating point type then the expression is called real arithmetic. All ways a float expression returns an exact or approximate result. Example: 20.5/6.4 returns 3.20313 Mixed-mode Arithmetic: When one of the operand is real and another is integer then the expression is called mixed mode arithmetic. If either operand is of real type, then other operand is converted into real type. The result of expression is converted into real type. Example: 15/10.0 returns 1.5 2. Relational operators: <, >, <=, >=, ==, != are the relational operators. These operators are used to compare any two values in order to take logical decisions. In java any relational expression returns either true or false. Example: 10<5 returns false



3. Logical operators: &&, ||, ! are the logical operators used to append multiple relational expressions to take a logical decision. In java any logical expression returns either true or false. && (And logical operator): Multiple relational expressions concatenated with “And” logical operator is called “And” logical expression. It returns true if all the relational expressions returns true. It returns false if any one of the relational expression returns false. Example: 10<20&&40<=40&&80!=20 returns true 40!=40&&80>20 returns true || (Or logical Operator): Multiple relational expressions concatenated with “Or” logical operator is called “Or” logical expression. It returns false if all the relational expressions returns false. It returns true if any one of the relational expression returns true. Example: 40>80||60!=80||20!=20 returns true ! (Not logical operator): It is a negation operator Example: ! (30<=20) returns true ! (40==40) return false 4. Assigning operator: = is an assigning operator used to assign the value of an expression to the variable. Java also supports short hand arithmetic operators. Short hand operators result more compact and easy readable code. +=, -=, *=, /=, %= are the short hand operators. Example: Int x=10; X+=20; //x becomes 30 5. Increment decrement operators: ++, -- are the increment and decrement operators used to increment and decrement the value of a variable by 1. These operators are used as both prefix and postfix operators. In case of prefix operator, the value of variable is incremented or decremented before other operations are performed. Example: Int x=40; Int y=++x; //the value of y is 41, x is 41



In case of postfix operator, the value of variable is incremented or decremented by 1 after other operations are performed. Example: Int x=40; Int y=x++; //the value of y is 40 and x is 41 6. Conditional operator: ?, : are two special operators used to write conditional expressions. Conditional expression is written in place of simple if else control statements. Syntax: Var = (condition) ? <exp1> : <exp2> According to the above syntax, if the condition is true then, the value of expression1 is assigned to variable otherwise the value of expression2 is assigned to the variable. 7. Bit-wise operators: Java provides different bit-wise operators to manipulate the data at bit level. These operators are mostly used to implement encrypt and decrypt algorithms for secured data communication. These operators are not used with float or double type of data. These operators are Logical bitwise and shift operators.

8. Special Operators: Java supports some of the special operators like instanceof, (.) member selection operator. Instanceof operator is used to check weather an object is belongs to a particular class. (.) member selection operator is used to select a member from an object.

Operator Meaning & bitwise AND | bitwise OR ^ bitwise XOR ~ One’s Complement << Shift left >> Shift right >>> Shift right with zero fill



2. Write about the Evaluation of arithmetic expression? (Or) Write about the presidency of arithmetic operators? Combination of constants, operands and arithmetic operators is called an arithmetic expression. Evaluation or execution of an arithmetic expression happens according to the priority or presidency of arithmetic operators. First expression will be evaluated and its result will be assigned to the variable. The precedence of arithmetic operators is as follows. Example: 3. Write about the presidency of operators in java Each operator in java has its priority. It determines how an expression is executed when more than one operator is existed with in an expression. The operators with highest priority are executed first. Operators with lower priority are executed next. The operators with the same priority are executed either from the left or right. Priority of operators is as follows. Priority: . () [] - ++ -- ! ~ (typecast) * / % + - << >> >>> < <= > >= instanceof == != & ^ | && || ?: = shortcut operators Associativity : Left to right: Arithmetic, relational, logical, increment/decrement, bit-wise and special operators Right to left : Unary minus, Conditional and assigning operator

Operator Presidency * / % 1st + - 2nd = Last

X= 9-4+3*2-1 (1st pass 3*2) X=9-4+6-1 (2nd pass 9-4) X=5+6-1 (3rd pass 5+6) X=11-1 (4th pass 11-1) X=10 (5th pass x=10)

10 x



4. Write about different Mathematical functions used in java? In java Different mathematical functions are defined with in the class java.lang.Math. All the mathematical functions available in c and c++ are defined as static methods in the Math class. Class java.lang.Math { ----------------- ----------------- Public static double sqrt(x) Public static double pow(x) Public static double sin(x) Public static double cos(x) Public static double tan(x) Public static double asin(x) Public static double acos(x) Public static double atan2(x) Public static double log(x) Public static double abs(x) Public static double acos(x) Public static double floor(x) Public static double ceil(x) -------------------- -------------------- } 5. Write about different control structures used in java? The control flow statements of a language determine the order of statements execution in a program. Java language supports the following control flow statements. 1. if statement 2. if-else statement 3. switch-case statement 4. break statement 5. continue statement



if-statement: - The if statement is used to control the flow of execution of statements. The general form of if statement is Syntax:

if (condition) { statements }

According to the above syntax if the condition is true, then the statements will be executed. If the condition is false, then the statements will be skipped from the execution. Ex: -

if (a>b) System.out.println(a);

if-else statement: - It is the control structure used to process two possibilities. The general form of if-else statement is Syntax: if (condition) { statements } else { statements } According to the above syntax if the condition is true, then statements under the if conditional statement are executed, otherwise the statements under the else part will be executed Ex: -

if(a>b) System.out.println(a); else System.out.println(b);



Switch Statement: - The switch statement causes a particular group of statements to be chosen from several available groups. The selection is based upon the current value of an expression that is included within the switch statement matches with the case constant associated with the case defintion. The general form of switch statement is

switch (<expression>) { case <const1>: statements break; case <const2>: statements break; default: statements }

Here the expression is evaluated first. If the value of expression matches with any of the case constant, then all the statements from proper case will be executed. However, if the value of expression doesn’t matches with any case constant labeled by the case keyword, then the default case is executed. When break statement is encountered, switch statement is terminated and any other remaining statements are ignored. A break statement is used to force an immediate exit from the control structure. break statement: - The break statement is used to terminate the execution of either switch or any iterative control structure. It can be used within a do-while, while, for or a switch statement. The break statement is written simply as break; The break statement causes the transfer of control out of entire switch statement or any loop, to the first statement following the switch statement or any loop. Syntax:

{ -------------- -------------- Break; ------------- ------------- }



Continue statement: - The continue statement is used to skip the execution of remaining statements of the loop and to proceed for the next iteration. The continue statement can be included within a while, a do-while or a for statement. It is written simply as continue;. Syntax: Note: java does not support goto control structure. 6. Write about the iterative or looping control structures in java? A single or block of statements executed repeatedly is called a loop or iteration. The java programming language uses three iterative or looping control structures to construct iterations. They are, 1. while loop 2. do-while loop 3. for loop while Iterative control structure: - It is the simple and fundamental iterative control structure. Which is used to execute a statement or group of statements repeatedly until a condition becomes false. It is an entry controlled iterative control structure. The general form while is as follows. Syntax:

While (condition) { block of statements }

According to the above syntax, the body of the loop will be repeatedly executed as long as the condition is true. The loop will be terminated when the condition is false. Ex:

fact=1;i=1;

{ -------------- -------------- Continue; ------------- ------------- }



while (i<=n) { fact=fact*i; i++; }

Do-while Iterative control structure: - The do-while iterative control structure works similar to while loop. The difference is that in case of do-while loop the condition is checked after the body of the loop is executed. So it is called exit controlled iterative control structure. It is only the control structure terminated with a semicolon. The general form of do-while statement is, Syntax: Do { statements }while(condition); According to the above syntax, the body of the loop will be executed as long as the condition is true. Ex: -

fact=1;I=1; do { fact=fact*I; i++; }while(I<=n);

for iterative control structure:- The for loop is the most commonly used iterative control structure in application development. However, the for loop is a flexible and powerful iterative control structure. It is an entry controlled iterative control structure. It has two parts. That is conditional statement and the body. The general form of the for statement is, Syntax: for(expression-1;expression-2;expression-3) { statements; }



Ex: for(i=1,fact=1;i<=n;i++) fact=fact*i; According the above syntax, expression-1 are the initialization statements of variables. It is executed once and at the beginning of loop execution. Expression-2 is the conditional expression. It is checked for each iteration of the loop. It determines the loop termination.Expression-3 is the increment or decrement expression. It changes the value of loop control variable. This expression is executed at the end of each iteration. 7. Define the following? a. Class b. Object a. Defining a Class: Class is a user defined type in java. Class definition has number of members. These include variables and the code. Variables declared with in the class are called data fields and the functions defined with in a class are called methods. Data fields are used to store the data in an object, where as methods are used to access, manipulate and store the data in the data fields. Class is similar to basic data type. A variable called instance or object has to create to store the data. Here the name of the class must be a valid identifier and must be in a capitalized format Syntax: Example: In the above example l, b are the data fields, which are used to store the length and breadth of rectangle. setSides() is a method used to

class <name> { Type nameofdatafield; Type nameofdatafield; Type nameofmethod(Parameters) { Statements; } Type nameofmethod(Parameters) { Statements; } };

class rect { int l,b; void setsides(int x,int y) { l=x; b=y; } int getarea() { return l*b; } };



set two sides of rectangle. getArea() is an another method used to get the area of rectangle. b. Creating an object: Defining a class may not allocate the memory allocation of any of its members, because class is a template. A variable or an instance belongs to class has to create to allocate the memory allocation of members. Instance of a class is called an object. Any number objects can be created belongs to a single class. Each object stores the data belongs to different entities. An object can be created in two steps.

1. Creating an object using new operator. 2. Storing the reference of object into the reference variable.

Example: Rect ob; (Creating the reference) Ob=new Rect(); (Creating the object) Accessing the class members: Class members can be accessed by using the member access operator (.). Syntax: <reference>.<member>(Parameters) Example:

ob Rectangle

Object

Import java.util.*; Class Rect { Int l,b; Void setSides(int x,int y) { L=x; B=y; } Int getArea() { Return l*b; } Int getPeri() { Return 2*(l+b); } }

Class Demo { Public static void main(String args[]) { Rect ob=new Rect(); Ob.setSides(4,5); System.out.pintln(“Area=”+ob.getArea()); System.out.println(“Perimeter=”+ob.getPeri()); } } O/p Area=20 Perimeter=18



Multiple references to a common object: Reference of one object can be assigned to another reference of the same type. Here object will not be copied but only the reference is copied. Example: Rect ob1=new Rect(); Rect ob2=ob1; 8. What is constructor? Constructor is a special kind of method used to initialize the data fields while creating an object. The following rules must be followed while declaring the constructor. 1. The name constructor must be equalant to the name of class 2. It cannot be defined as private 3. It may accept any number of arguments. 4. It doesn’t return any value. 5. It cannot be called once an object is created. Syntax: <name of class>(list of arguments) { Statements } Example:

Rectangle Object

Ob1

Ob2

Class Rect { Int l,b; Rect(int x,int y) { L=x; B=y; } Int getArea() { Return l*b; } };

Class Demo { Public static void main(String args[]) { Rect ob=new Rect(3,4); System.out.println(“Area=”+ob.getArea()); } } O/p Area=12



9. Write about the method overloading? In procedural languages it is not possible to define multiple functions with the same name. But in any object oriented programming language like java, it is possible to define multiple functions with the same name. While defining multiple functions with the same name, make sure that the difference is provided in parameters. Difference in parameters can be provided by making the difference in number, type and sequence of arguments. Proper method is selected according to the arguments we send to the method. Example: 10. Write about the static members? The normal data fields and methods defined in a class are called instance members. Because these are created every time a new object is created. Both the data fields and methods can be defined as static members using static keyword. Static members are called class members, because these members are common to all the instances of a class. These members can be directly accessed either by the class name or any instance belongs to the class. Static data fields: The data fields defined with the keyword static are called static data fields. The se data fields are used to define constants. These are written in capitals to identify that it is a constant.

Class Rect { Int l,b; Void setSides(int x) { L=b=x; } Void setSides(int x,int y) { L=x;b=y; } Int getArea() { Return l*b; } }

Class Demo { Public static void main(String args[]) { Rect ob1=new Rect(); Ob1.setSides(3); Rect ob2=new Rect(); Ob2.setSides(4,5); System.out.println(“Area of Square”+ob1.getArea()); System.out.println(“Area of rectangle”+ob2.getArea()); } } O/p Area of Square 9 Area of rectangle 20



Static method: The methods defined with the keyword static are called static methods. These methods are used as the utility functions in java. Example: Math is the class of java.lang package. It defines different constants and methods to perform mathematical operations. Example of usage of static members: The static members have several restrictions:

1. Static methods can call only static members 2. These can only access static data 3. These cannot refer to this and super.

Class Math { Static final double PI= -----; Static final double S= -----; Static double sqrt(double x) Static int pow(int b,int e) -------------------- -------------------- }

Class Circle { Static double getArea(int r) { Return Math.PI*Math.pow(r,2); } }; Class Demo { Public static void main(String args[]) { Double x=Circle.getArea(7); System.out.println(“Area of circle”+x); } }



11. Write about the nesting of methods? Calling a method by another method of the same class is called nesting of methods. In the above example object calls the input() method. In return it calls the method sum(). 12. Write about the inheritance in java? Inheritance is one of the important features of any object oriented programming language. The mechanism of deriving a new class from an old one is called inheritance (or derivation). The old class is called as the super class and the new one is called the sub class. It supports the concept of hierarchical classification. In OOP, the concept of inheritance provides the idea of reusability. This means that we can add additional features to an existing class without modifying it. This is possible by deriving a new class from the existing one. The new class will have the features of both super and sub classes. Advantages: 1. Inheritance allows to construct re-usable components. 2. A common code can be used in different modules. 3. Enhancements can be done to the existed classes. 4. The behavior existed class can be changed by overriding the members.

Import java.util.*; Class Nesting { Int x,y; Void input() { System.out.println(“Enter two numbers:”); X=(new Scanner(System.in)).nextInt(); Y=(new Scanner(System.in)).nextInt(); sum(); } Void sum() { System.out.println(“Sum=”+(x+y)); } }

Class Demo { Public static void main(String args[]) { Nesting ob=new Nesting(); Ob.input(); } }



Forms of Inheritance:- The mechanism of deriving a new class form an old one is called inheritance (or derivation). Inheritance is classified into different forms based on the levels of inheritance.

1. Single inheritance. 2. Multiple inheritance. 3. Multilevel inheritance. 4. Hierarchical inheritance.

Single Inheritance: Inheriting a single class into another class is called single inheritance. According to the syntax class A has the members of only A. class B has the members of both A, B. Here the existed class A is called super class and the new class B is called sub class. Multiple Inheritance: Inheriting multiple classes into a single class is called multiple -inheritance. Java does not support multiple-inheritance with classes. But supports through interfaces.

A

B

class A { ------------- ------------- }; class B extends A { ------------ ------------ };

A B

C

interface A { ------------- ------------- }; interface B { ------------ ------------ } class C implements A,B { ------------ ------------ }



Multilevel inheritance: Inheriting the sub class of one class into another class is called multilevel inheritance. According to the syntax class A is the super class. Class B is the indirect super class. Class C is the sub class. Class A has the members of A. class B has the members of both A, B. class C has the members of A, B, C. Hierarchical Inheritance: Inheriting a single class into multiple classes is called hierarchical inheritance. According to the syntax class A is inheriting into multiple classes that is B, C. Both the classes B, C have the members of A.

A

B

C

class A { ------------- ------------- }; class B extends A { ------------ ------------ } class C extends B { ------------ ------------ };

A

B C

class A { ------------- ------------- }; class B extends A { ------------ ------------ } class C extends A { ------------ ------------ };



13. Write about the overriding of methods? When the super, sub classes have the methods with the same name, arguments and return type then, sub class members overrides the super class members with in the sub class object. Overriding is used to change the behavior of a method while using all other resources of a class. Example: In the above example, the sub class object has the methods of both the super and sub class. But the sub class object can access the sub class methods, because sub class methods override the super class methods. 14. Write about the final data fields, final methods and final classes? Final is the key word used to declare the final data fields, methods and classes. Final data fields: The data fields defined with the key word final are called final data fields. The values of which are assigned while their declaration. The values of final data fields cannot be changed. These are used to define the constants.

Import java.util.*; Class First { Int x; Void setNum() { System.out.print(“x=”); X=(new Scanner(System.in)).nextInt(); } Void output() { System.out.println(“x=”+x); } } Class Second extends First { Int y; Void setNum() { Super.setNum(); System.out.print(“y=”); Y=(new Scanner(System.in)).nextInt(); }

Void output() { System.out.println(“x=”+x); System.out.println(“y=”+y); } } Class Demo { Public static void main(String args[]) { Second ob=new Second(); Ob.setNum(); Ob.output(); } } O/p x=45 Y=30 X=45 Y=30



Example: Final methods: The methods defined with the keyword final are called final methods. These methods can be used as normal methods. But, final methods cannot be override in its sub classes to change their behavior. Final class: These are the classes defined with the keyword final. Final classes work like normal classes. But, these classes cannot be extended into other classes. 15. What is finalizer method? Constructor is a special kind of method used to initialize the object. It executes while creating an object. Finalize() is also a special kind of method executes when object is de-allocated by the garbage collector. The purpose of finalize method is to clean up not object resources like file descriptors and windows system fonts etc. Syntax:

Class Thread { Final static int MIN_PRIORITY=1; Final static int NORM_PRIORITY=5; Final static int MAX_PRIORITY=10; -------------------- --------------------- };

Class Box { Int b,w,h; Box(int x,int y,int z) { B=x; W=y; H=z; } Int getVolume() { Return b*w*h; }

Finalize() { System.out.println(“Object is being clared”); } };



16. What is abstract method or abstract class? Abstract method is a method which has no implementation that is no body. The abstract method must be defined with the keyword abstract. If any class has at least a single abstract method then the class is called an abstract class. An object belongs to abstract class cannot be created unless we override all the abstract methods in its sub class.

1. We cannot create an object belongs to the abstract class. 2. All the abstract methods of the abstract class must be override in its

sub class 3. We cannot define either abstract constructor or static method

Example: 17. Write about the visibility control or specifiers? (Or) Write about the access modifiers in java? In general all the members of super class are extended into the sub class. Some times, it is needed to restrict the members to access and extend. Java provides different visibility specifiers to control the access and extend. These are default, private, protected and public. Default: If we do not specify any specifier then it is called default member. These members can be accessed and extended any where with in the program. Default members of other packages can not be accessed and extended. Public: Public members have global access. These can be accessed and extended any where with the program and other packages. Private: Private specifier is used to promote data hiding or protection in any object oriented programming language. The visibility of private members is limited to the same class.

abstract class Result { Abstract void setMarks() Abstract void getResult() };



Protected: Protected members works like default members with in the same program. Protected member of other packages cannot be accessed but can be extended into the sub classes.

Modifier Access

Default Public Protected Private

Same class Yes Yes Yes Yes

Other class same package Yes Yes Yes No

Sub class same package Yes Yes Yes No

Other class other package No Yes No No

Sub class other package No Yes Yes No



UNIT III 1. Define Array? (Or) Write about a single dimensional array? A variable belongs to any type can store maximum a single value. An array is a derived type used to store multiple values with the same name. Array: An array is a set of elements belongs to the same type stored in consecutive memory allocations. All the elements are represented by the same name. Every element in the array is identified with its index. In java index of the first element is ‘0’ and the index of the last element is ‘n-1’. Where n is the size of array. Creating an Array: An array is created in three steps.

1. Creating the reference 2. Allocating the memory 3. Storing values in it

The reference of an array is created with the type and the name of reference. Memory allocation of array elements is done using the new operator. Type and size of array is specified while creating an array. Values to an array are initialized using the name of array and its index.

x int[] x; (or)

int x[];

int[] x=new int[5];

x

x[0]=10; x[1]=20; x[2]=x[0]+x[1]; x[3]=x[0]-x[1]; x[4]=x[0]*x[1];

x 10 20 30 -10 200



Initializing while declaration: Set of elements are initialized while declaration of an array without using the new operator. Length: Length is the property of an array. It returns the length of an array. In the above example ‘x.length’ gives 5. 2. Write about the Two-Dimensional array?

(Or) Define the matrix?

Two Dimensional array: Set of single dimensional arrays of the same size referred with the same name is called a two dimensional array or matrix. A matrix is defined in two steps, which is defining the reference and allocating the memory allocation of matrix using ‘new’ operator. While defining the matrix number of rows and columns are specified. Syntax: Exmaple: Initializing while declaration: Set of sets of elements can be initialized while declaration of a matrix. Example:

int[] x={10,20,50,60,80}

x 10 20 50 60 80

int x[][]=new int[3][4];

Type name[][]=new type[rows][cols]

Int x[][]={{2,3,4,5,6},{6,5,4,3,2},{15,24,34,43,52}};

x

2 3 4 5 6

6 5 4 3 2

15 24 34 43 52

x[0][3]

x[1][1]

x[2][2]



Variable size array: An array with variable number of columns can be created. To create variable size array, first create an array of references and then allocate the memory allocation of individual rows using ‘new’ operator. Example: 3. Write about the String handling in java? Set of characters place in double quotations is called a string. In c, c++ a string is considered as a single dimensional character array. In java String is a user defined type. Whenever a string is created java runtime creates an object belongs to String class and initialized through its constructor. String handling: The string class has number of methods. By using which we can perform string operations.

int [][]=new int x[3][]; //creating reference array x[0]=new int[2]; //creating individual rows x[1]=new int[4]; x[2]=new int[3];

x[0] x[1] x[2]

String str=”Nice”; Is equalant to

String str=new String(“Nice”);

Class String { String toUpperCase() // To convert into Uppercase String toLowerCase() // To convert into lowercase int length() // To find the length of string char charAt(int) // to get a character at index int CompareTo(String) // To compare two strings int indexOf(char ch) // To find the index of a character from front int lastIndexOf(char ch) // To find the index of a character from front boolean equals(String) //To compare two strings boolean equalsIgnoreCase(String) // To compare two string by ignoring case ------------------- ------------------- }



StringBuffer: StringBuffer is a sub class to the class String. It is used to create variable length string. It provides different methods to insert a character, a string any where with in the string, append a string etc. 4. Write about the vector? Vector is class defined in java.util. This class can be used to create a generic and dynamic array called vector. A vector can hold any number of objects of any type. Size of vector is specified while creating an object belongs to vector. Though the size is specified unlimited number of objects can be stored. Advantages of vectors: 1. Any type of objects can be stored 2. Any number of objects can be created 3. Object can be inserted, deleted and appended

The vector class has following methods:

Class StringBuffer { Void setCharAt(int index, char ch) //modify a character at index Void append(String str) //Appends a string Void insert(int index, String str) //Inserts a string ---------- ---------- }

Class Vector { Void addElement(Object) // To add an object Int size() // Returns the size of vector Void removeElement(Object) // Removes an element Void removeElementAt(int) // Removes element at an index Void removeAllElements() // Remove all the elements Void insertElementAt(Object,int) // Inserts element at index Void copyInto(Object[]) // Stores Objects into array -------------------- -------------------- }



Example: 5. Write about the wrapper classes? The utility collection classes like Sets, Lists and Maps do not accept primary types, accepts only objects. To handle Collection classes’ primary types must be converted into object types. Java.lang package provides wrapper classes to wrap primary types with the objects. Almost every primary type has its wrapper class. These classes are the sub classes to the class Number.

Import java.util.*; Class Demo { Public static void main(String args[]) { Vector v=new Vector(); v.addElement(“Basic”); v.addElement(“Cobol”); v.insertElementAt(“Pascal”,1); String x[]=new String[v.size()]; v.copyInto(x); for( int i=0;i<x.length;i++) System.out.println(x[i]); } } O/p Basic Pascal Cobol

Number

Integer Float Character Long Double Byte Short

Class Number { int intValue() float floatValue() char charValue() ------------- ------------- }



These wrapper classes helps to refer collection of elements belongs to different types as single set. 6. Define interface? (Or) What is interface and write how an interface is implemented? An interface is a special kind of class. An interface is used on two purposes, which are to define the constants and to define the specification. Data fields and methods can be defined in an interface like a normal class. The data fields defined with in a class are by default final static data fields. These data fields are mostly used to define the constants. These constants are accesses with the name of interface because, these are of static type. The values of these data fields cannot be changed because, these are of final type. The methods defined within an interface are by default public abstract type. Hence an interface is called as a pure abstract class. An instance belongs to an interface cannot be created unless we override the abstract methods in its implementing class.

class Demo { public static void main(String args[]) { Object x[]=new Object[5]; x[0]=new Integer(12); x[1]=new Float(45.23f); x[2]=new Character(‘x’); x[3]=new Double( 67.45); x[4]=new Long(2345); for(int i=0;i<x.length;i++) System.out.println(x[i]); } }

O/p 12 45.23 X 67.45 2345

Interface Constants { Double PI=3.14; };



Syntax: Multiple inheritance: Multiple interfaces can be extended in a class and multiple interfaces can also implement in a single class Example:

Interface <Name of interface> { ---------------- --------------- } Class <name of class> implements <Name of interface> { ---------------- ---------------- }

Interface Constants { Double PI=3.14; } Interface Circle { Void setRad(int x); Double getArea(); Double getCir(); } Class CircleImpl implements Constants, Circle { Int rad; Public void setRad(int x) { Rad=x; } Public double getArea() { Return Pi*rad*rad; } Public double getCir() { Return 2*PI*rad; } }

Class Demo { Public static void main(String args[]) { Circle ob=new CircleImpl(); Ob.setSides(7); System.out.println(“Area=”+ob.getArea()); System.out.println(“Circumfarance=”+ob.getCir()); } }

Constants Circle

CircleImpl



7. What is a package and write the procedure to create a package? Reusability is one of the important features of java. Java supports reusability by extending classes and implementing interfaces. Package: Package is a collection of re-usable classes and interfaces. Once the package is defined, then its resources can be accessed into any java program. Import statement is used to import a class or all the classes of a package. Advantages of packages:

1. Promotes the re-usability 2. Two classes can be defined with the same name in different packages 3. Helps to hide a class 4. It separates the designing from coding.

Java API packages: Java API provides a large number of classes grouped into different packages and sub packages according to functionality. This API is used to develop java applications. Package Name Purpose Java.lang These are the classes directly used by the compiler. These classes

are directly imported into every application Java.util Provides number of utility classes like collections classes and to

perform date and time operations Java.io Provides number of classes to perform different input and output

operations Java.awt Provides number of classes to design graphical interface Java.net Provides number of classes to do network programming Java.applet Provides number of classes to develop applets Creating a package: We can create our own package in order to re-use in different applications. A package can be created in 3 steps

Import java.util.*; // It imports all the classes of util package Import java.util.Date; // It imports the Date class from util package

java

lang util net awt io



1. Creating a folder with the name package 2. Defining classes/interfaces in the package folder 3. Compiling the classes/interface 4. Setting the class path to the parent folder of package 5. Accessing the package and its classes

Step1: Creating the folder with the name of package Step2: Defining the classes under the package folder The class definition must be started with the package statement. The class and all its methods must be of public type. Step3: Compile all the classes of package Step4: Setting the class path to the parent folder Step5: Accessing the package

C:\>md shape

C:\>cd shape C:\Shape> edit Box.java package shape;

public class Box { Int b, w, h; public void setSides(int x, int y ,int z) { B=x;w=y;h=z; } public int getVolume() { Return b*w*h; } }

Shape>javac Box.java

D:\> set classpath=c:\;.;

import shape.*; class Demo { Public static void main(String args[]) { Box ob=new Box(); Ob.setSides(3,4,5); System.out.println(“Volume=”+ob.getVolume()); } }



UNIT IV 1. What is a thread? Write how java supports multi-threading? (Or) Explain how to create a thread in java? Thread: Executing multiple programs simultaneously is called multi-threading. Multi-threading is a conceptual programming where a program is divided into two or more sub programs and are implementing at the same time. A unique property of java is its ability to support multi-threading. In java multiple threads are defined as multiple blocks of code. Execution of java application always starts from the main method called main thread. The main thread starts all the other threads called sub threads. All the threads execute in parallel one after another. Creating threads in java: In java a thread can be created in two ways that is

1. By extending the Thread class 2. By implementing Runnable interface

Switching Switching

Class Demo { Public static void main(String args[]) { ---------------- ---------------- } }

------------ ------------ Public void run() { ------------ } ------------

------------ ------------ Public void run() { ------------ } ------------

------------ ------------ Public void run() { ------------ } ------------

Thread1 Thread2 Thread3

Main Thread



Creating a thread by extending the Thread class: Java.lang.Thread is an implementing class of Runnable. It has all the life cycle methods to create and control the thread. Start() method of Thread class registers the thread to the O.S, which calls the run() method. By default run() method has nothing to execute. We can place thread code with in the run() method by overriding in the extending class of Thread. Example: Creating a thread by implementing Runnable interface Runnable interface has single public abstract method called run(). We cannot create a thread by implementing Runnable interface alone, because it has no other methods to create and control the life of a thread. To create a thread by implementing Runnable interface, we also take the help of Thread class and it methods. The following steps are taken to create a thread by implementing Runnable interface.

Class MyThread extends Thread { int st, end; MyThread(String str, int s, int e) { super(str); st=s; end=e; setPriority(5); start(); } public void run() { for(int i=st;i<=end;i++) System.out.println(getName()+”:”+i); } } Class Demo { public static void main(String args[]) { new MyThread(“one”, 1, 100); new MyThread(“two”, 101, 200); new MyThread(“Three”, 201, 300); } }

O/p One 1 Two 101 Three 201 One 2 Two 102 Three 202 ----------- -----------



1. Implementing the Runnable interface by overriding run() method. 2. Sending the reference of Runnable implanting object to the Thread

object. 3. Calling the start() method of Thread object.

2. Write about the life cycle of thread? During the life time of thread it is at different states. These include,

1. Newborn state 2. Runnable state 3. Running state 4. Blocked state 5. Dead state

1. New born state: The state of thread on creating an object belongs to thread is called new born state. Example:

Class MyThread implements Runnable { Public void runnable() { For(int i=1;i<=50;i++) System.out.println(“One:”+i); } } Class Demo { Public static void main(String args[]) { MyThread ob=new MyThread(); Thread th=new Thread(ob); th.start(); for(int i=51;i<=100;i++) System.out.println(“main:”+i); } }

MyThread th=new MyThread();

New born state



2. Runnable state: On calling the start method of thread object, Thread is registered with the queue of threads of O.S. O.S sends the thread to the runnable state that is ready to run state. 3. Running: Executing the statements of a thread is called the runnable state. When one thread is executing, other threads will be at waiting state called runnable state. A thread will be swapped among the runnable and running states. 4. Blocked state: Sleep: When the sleep method is called, then the thread will be send to the blocked state for specified number of milliseconds. It will automatically come to the running state after the completion of specified milliseconds.

th.start();

New born state

th.start();

New born state

Runnable Running

Other Threads

Blocked

th.start();

New born state

Runnable Running

th.sleep(1000); After 1 sec



Suspend(), resume(): Suspend is the method, which sends the thread into the blocked state. It will come to the running state on resume() is called. 5. Dead state: The thread goes to the killed state either after completion of thread execution or by calling the stop() method. 3. Write about the priority of threads? Each thread is assigned with a priority. Processor time is given more to the threads with more priority, less to the threads with less priority. By default a thread is assigned with the normal priority 5. The thread class defines 3 constants to assign the priority to the threads. Example: MyThread th1=new MyThread(); th1.setPriority(Thread.NORM_PRIORITY); th1.start();

Blocked

th.start();

New born state

Runnable Running

Suspend() Resume()

Class Thread { Final static int MIN_PRIORITY=0; Final static int NORM_PRIORITY=5; Final static int MAX_PRIORITY=10; ------------------------ ------------------------ };



4. Write about the Synchronization and dead lock? Synchronization: When multiple threads using the common resource then sometimes, it may leads to serious problems. For example a method is used to perform read and write operations on the file, multiple threads are using the same method to perform opposite operations then, it results unexpected result. If the commonly used method is defined as Synchronized method then a monitor is placed on a thread first called. Another thread is executed on the completion of first thread execution. Synchronization is done two ways

1. By defining the commonly used method as synchronized method using the keyword Synchronized. Example:

2. By placing the commonly used object in the Synchronized block Dead lock: Dead lock occurs when two synchronized methods have circular dependency on a pair of synchronized objects. For Example one thread enters the monitor on object X and another thread enters the monitor on object Y. If the thread in X tries to call any synchronized method on Y, thread in Y tries to call any synchronized method on X, then it results dead lock.

synchronized static void display(String name, int st, int end) { for(int i=st;i<=end;i++) System.out.println(str+” “+i); }

synchronized(ob) { Ob.display(getName(), st, end); }

synchronized method2() { method1(); }

synchronized method1() { method2(); }

Thread1 Thread2



5. Write about the types of errors in java? Error or bug is an abnormal event in a program, causing the program to produce unexpected result or some times terminate the execution. According to the root of errors, errors can be classified into

1. Compile time errors 2. Run time errors

Compile time errors: All syntax errors are considered as compile time errors. These errors are recognized and reported by the compiler during the compilation of program. Compiler will not generate byte code unless compile time errors are rectified. The most common errors are:

1. Missing semicolons 2. Missing of {} 3. Misspelling keywords and identifiers 4. Use of undeclared variables 5. Improper type casting etc.

Runtime-errors: Sometimes, a program may compile properly and successfully produces the byte code, but may not run properly. Such programs may produce bad result or terminate abnormally. The most common run-time errors are:

1. Due to the bad logic used in program 2. Dividing an integer by zero 3. Accessing negative index of an array 4. Using null objects 5. Invalid conversion from string to number etc.

6. What is exception and write different exceptions in java? An exception is an abnormal event which causes program to produce abnormal result, terminates the execution of program. Divide by zero is an exception rises on dividing an integer by zero. Java provides a hierarchy of classes to handle the exceptions in java. Throwable is the super class to all the hierarchy. It is the solid class defines all the methods used to handle the exceptions.



Arithmetic Exception: Rises when an integer is divide by zero ArraIndexOutOfBoundsException: Raises when a negative index or an index which is beyond its size is accessed NullPointerException: Rises when a reference with a null value is used to access members ClassNotFoundException: Rises when class loader fails to load the class either in the current folder or in classpath directory NumberFormatException: Rises when fails to convert a string into number. IOException: Rises when program fails to access, write on to console. How an exception is raised: When the java runtime encounters a run time error, then java runtime creates an object belongs associate class. The exception object is stored with the source and details of exception. If the exception is not handled by the program then it will be handled by the default exception handler by terminating the program execution. The default exception handler publishes the details of exception on console.

ExceptionObject

Source and Details of Exception

Throwable

Exception

ArithmeticException

ArrayIndexOutOfBoundsException

NullPointerException

ClassNotFoundException

NumberFormatException

IOException



7. Write about the exception handling in java? (Or) Write how to use multiple catch blocks? Run-time errors which can be handled are called exceptions. Java provides try-catch mechanism to handle the run-time exceptions. The source of exception is placed with in the try block. One or more catch blocks are defined under the try block. Catch block is not executed when there is no exception with in the try block. When there is an exception raised with in the try block then an object belongs to exception is created and its reference is send to the matching catch block. Here the catch block is used to handle the exception. Program execution resumes after the completion of catch block execution. If the type of exception does not match with any of the catch blocks then exception is handled by the default exception by terminating the program. Syntax: In the above example when the denominator is zero ArithmeticException is raised and handled. When the denominator is not a number then InputMismatchException is raised.

Import java.util.*; Class Demo { Public static void main(String args[]) { int x, y, z; try { System.out.println(“Enter two numbers”); X=(new Scanner(System.in)).nextInt(); y=(new Scanner(System.in)).nextInt(); z=x/y; System.out.println(“Division=”+z); } catch(ArithmeticException ae) { System.out.println(“Cannot devide by zero”); } catch(InputMismatchException ime) { System.out.println(“Inproper Input”); } } }

run 1: Enter two numbers 5 0 Cannot divide by zero run 2: Enter two numbers 15 xy Inproper Input run 3: Enter two numbers 15 3 Division=5



8. Write about the finally block? Finally block is used in association with either try or try-catch block. It is the compulsory to execute block. It executes in all the case that is

When no exception raised Exception raised but not handled Exception raised and handled.

It is mostly used to close the opened database connections and to close the opened files. Syntax: ---------------------------- 9. Write about the user defined exceptions? (Or) Write how to throw an exception? All the exception classes are the sub classes to the class Exception, which is the sub class to the class ‘Throwable’. Only the run-time exception are identified and handled by the java run time. Logical errors can not be identified and handled by the java runtime. We can define our own exception type by extending ‘Exception’ class. As java run time do, we can Hit the exception (Finding the exception) Throw the exception using throw statement Catch the exception using catch block

try { } finally { }

try { } catch(Exceptiontype e) { } finally { }



Example:

import java.util.*; class MyException extends Exception { MyException(String str) { super(str); } } class Demo { public static void main(String args[]) { int cmr, pmr, nu; float bill; System.out.print(“Enter the cmr:”); cmr=(new Scanner(System.in)).nextInt(); System.out.print(“Enter the pmr:”); pmr=(new Scanner(System.in)).nextInt(); try { If(pmr>cmr) throw (new MyException(“Invalid readings”)); Nu=cmr-pmr; Bill=nu*3.75; System.out.println(“No.of units:”+nu); System.out.println(“Total bill:”+bill); } catch(MyException me) { System.out.println(me.getMessage()); } finally { System.out.println(“It is the end of program”); } } }

Run1: Enter the cmr: 500 Enter the pmr: 200 No.of units: 300 Total Bill: 1125 It is the end of program Run 2: Enter the cmr: 200 Enter the pmr: 500 Invalid readings It is the end of program



10. Write how applet differs from a java application? (Or) Why do we need applets? (Or) What is an applet? HTML is a web based programming language used to develop web pages. Web pages developed in HTML are static web pages. These web pages can present the formatted data but cannot interact with the users, because HTML has no data types, control structures, functions and user interface controls to provide interaction. Applet: An applet is a small java program placed with in a HTML document. Applet is byte code compiled from a java program (.class file). Applet is loaded in to the computer along with the HTML page. Applet is executed by the java runtime loaded in the computer. Applets are used to perform arithmetic operations, display graphics, play sounds, accept user input, create animation and play interactive games. How applet differs from a java application? Though applet is a small java program, it is not a fully featured java application. Since applets are used in internet, there are certain limitations in developing applets.

1. Applet has no main() method. Execution starts in pre defined order. 2. Applet cannot be an individual program. It must be place within the

web page. 3. Applet must be small to easily download in internet 4. Applet cannot access the file system of local system 5. Applet cannot start any program in the local system 6. Applet cannot communicate with other servers 7. Applets are restricted from using C and C++ libraries.



11. Write the procedure to develop and execute an applet? (Or) How to create an executable Applet? (Or) Write steps to develop an applet? The following procedure is followed in developing and executing an applet. Step1: Building Applet Code Java.applet package provides a class called Applet. It has all the life cycle methods of Applet. Graphics is the class of java.awt has the methods to paint on the banner of an applet. To create an applet, Applet class is extended into our own class. Init () method is overrided to initialize the applet, start() method is overrided to set the background and foreground and paint(Graphics) method is overrided to paint on to the banner using its methods. Step2: Creating executable Applet Compile the applet using the java compiler. It produces the executable Applet in a form of .class file

import java.applet.*; import java.awt.*; public class MyApplet extends Applet { String str; public void init() { str=”Hello world”; } public void start() { setForeground(Color.red); } Public void paint(Graphics g) { g.drawString(“Hello world”,50,100); } }

>javac MyApplet.java



Step3: Adding applet to the HTML page <Applet> tag is used to add applet to the html page. Applet is added to the HTML page in the body section Step4: Executing the applet Appletviewer is used to execute the applet. 12. Write how to design a web page? HTML is the formatting language used to develop web pages. Collection of we pages is called as a web site. Individual web pages are inter-connected using hyper links. HTML has no data types, control structures and functions. It has only tags to format the web page. Tag is a key word placed with in “< >”. Tags are of two types that is singular and container. Singular tag has only the beginning part, where as container tag has both the beginning and ending parts. Any HTML program is saved with .html extension and executed by any web browser like Internet explorer, Netscape Navigator or Mosaic etc. Total web page is written with in <html> and </html> tags. Any HTML page has three sections.

1. Comment Section 2. Head Section 3. Body Section

Comment Section: It is an optional section in web page. This section is used to write the details of a web page and developer etc. It will not be executed by the browser.

<html> <head> <title>Demo of Applet</title> </head> <body> <Applet code=”MyApplet.class” width=300 height=300> </Applet> </body> </html>

>Appletviewer MyApplet.html

Head Section: It is an optional section in web page. This section is used to interact with the browser and other programs. Body Section: It is the mandatory section HTML. All the contents written in the body section will be printed on the browser. Example: 13. Write about the Applet tag? <APPLET> is a html tag used to add an applet to the HTML document. It has different attributes to format the applet in a HTML document. Attributes Purpose Codebase To specify the name of applet and its location (URL an applet) Code To specify the name of applet with .class extension With To specify the with of applet (In pixels) Height To specify the height of applet (In pixels) Align To align the applet with respect of web page (left, right and

center) Name To specify the name of Applet to refer in script Vspace To specify the vertical space among the applet and text Hspace To specify the horizontal space among the applet and text Param It is tag within the <Applet> tag used to send the parameters to

the applet from HTML page.

<HTML>  <HEAD> <TITLE>My first page</TITLE> </HEAD> <BODY > <H1>Hello world</H1> <BODY> <HTML>



14. Write about the Life cycle of an applet? Every applet inherits all of the life-cycle methods from Applet class. An applet undergoes into different states while its execution. These states includes

1. New born or initialization state 2. Running state 3. Idle state 4. Dead or destroyed state

Vspace

Hspace

Height

Width

Browser loads the Applet

Creates the object belongs to applet init()

Initializing state

start()

Running state

Public void paint(Graphics g) { ---------------- ---------------- }

Object belongs to Graphics

Idle State

stop()

destroy()

Dead state End (Exit from browser)

Loosing & Gaining focus

Restart



New born state: On loading the applet, the run-time creates an object belongs to applet class and calls init() method. The state of which is called initialization state. The init() method is used to initialize the values, set the foreground and background color of the applet. Running state: The applet enters into the running state when run-time calls the start() method. The start method is used to create threads Display State: After the execution of start method run-time creates an object belongs to Graphics and send its reference to paint() method. The paint method paints the banner using the methods of Graphics class. Idle or stopped state: Once the paint method is executed then applet goes to the idle state and executes the stop() method. The stop() method is used to terminate the Threads Dead state: Applet goes to the dead state on unloading the applet from memory by terminating from the web page. The destroy() method is executed on sending the applet to the dead state. 15. Write how to send parameters to an applet? (Or) Write about the <param> tag? (Or) Write about the HTML to Applet communication? <Param> is the tag used to send the parameters from an html page to the applet. The <param> tag has two attributes that is name and value. Here the ‘name’ specifies the name of parameter and values specifies the value to be send to the applet. Applet has a method called getParameter (), it accepts the name of parameter as argument and gets the value from the applet. <Param> tag is used to customize the applet from html page. Example:



Writing an Applet: Sending parameter to Applet: 16. Write about the HTML tags? HTML is tag based programming language used to format the web-page. Here tag is keyword placed with in < >. Tags in HTML cab divided into singular and container tags. Singular tag has no closing part, where as container tag has both opening and closing parts. The following are some of the important tags used in HTML.

import java.applet.*; import java.awt.*; public class MyApplet extends Applet { String str; public void init() { str=getParameter(“one”); } public void paint(Graphics g) { g.drawString(str,50,100); } } >javac MyApplet.java

MyApplet.html <html> <body> <center> <applet code=”MyApplet.class” width=300 height=300> <param name=one value=”Hello world”> </applet> </center> </body> </html> >Appletviewer MyApplet.html

Tag Purpose <br> Next line character <b></b> To format the text in bold <i></i> To format the text in italic <u></u> To format the text in underline <h1></h1> ----------- <h6></h6>

To format the headings

<center></center> To align the text in center <p> To give the paragraph break <Hr> To draw the horizontal line <Font></font> To format the font <Img> To place an image in a HTML page <Applet></applet> To insert an applet in a HTML page <!-- Commentation in html 17. Write an applet which interacts with the user. (Or) Develop font animation applet? Example:

//<applet code="MyApplet.class" width=300 height=300></applet> import java.applet.*; import java.awt.*; import java.awt.event.*; public class MyApplet extends Applet { TextField txt1; Label l1,l2; Button b1; public void init() { setLayout(null); l1=new Label("Enter text"); l1.setBounds(50,50,100,25); add(l1); txt1=new TextField(); txt1.setBounds(175,50,100,25); add(txt1); l2=new Label(); l2.setBounds(50,150,225,100); add(l2);



O/p

b1=new Button("Start"); b1.setBounds(100,100,100,25); add(b1); b1.addActionListener(new Listener()); } class Listener implements ActionListener { public void actionPerformed(ActionEvent ae) { String str=txt1.getText(); Font f; for (int i=5;i<=20;i++) { try{Thread.sleep(300);}catch(Exception e){} f=new Font("Arial",Font.BOLD,i); l2.setFont(f); l2.setText(str); if(i==20) i=5; } } }; };



UNIT V 1. Write about the Bubble sort? It is the easiest sorting method. It is the reverse to the selection sort. The basic idea behind the bubble sort is to pass through the list several times. In each pass we compare each element in the list with its next elements, that is a[i] with a[i+1]. We exchange them when they are not in order. Algorithm:

1. Repeat through step4 a total number of n-1 times 2. Repeat step3 for elements in unsorted portion of the vector 3. If the current element in the vector is greater than next element in the

vector then exchange element. 4. If no exchanges were made then return, else reduce the size of the

unsorted vector by 1 Example: Pass1: After pass2: After pass 3:

33 44 22 11 66 55 33 44 22 11 66 55 33 22 44 11 66 55 33 22 11 44 66 55 33 22 11 44 66 55 33 22 11 44 55 66

22 11 33 44 55 66

11 22 33

55 66 44

return



Implementation: 2. Write about the selection sort? One of the easiest ways to sort a list is by selection sort. Beginning with the first element in the list, search is performed to locate the element which has the smallest value. When the smallest element is found then it is exchanged with the first element in the list. A search for the second smallest element is then found. It is exchanged with the second element. It must be continued for the total list. Algorithm

1. Repeat through step5 a total of n-1 times 2. Record the portion of the vector already sorted 3. Repeat step4 for the elements in the unsorted portion of the vector 4. Record location of the smallest element in unsorted vector 5. Exchange first element on unsorted vector with smallest element

Example:

void bubblesort(int p[],int n) { int l, temp, i, exg; for(l=n-1;l>0;l--) { for(exg=0,i=0;i<l;i++) { if(p[i]>p[i+1]) { temp=p[i]; p[i]=p[i+1]; p[i+1]=temp; exg++; } if(exg==0) return; } } }

42 23 74 11 65 58 11 23 74 42 65 58 11 23 74 42 65 58 11 23 42 74 65 58 11 23 42 58 65 74



Implementation: 3. Write about the Insertion sort? It is a sorting method by using which we can sort the elements either in ascending or descending orders. The following algorithm is used to sort the element using inserting sort. Algorithm The insertion sort algorithm scans ‘a’ from a[0] to a[n]. Inserting each element a[k] to its proper position in the previously sorted sub array a[0], a[1], a[2],……………….a[k-1]. This is Pass1: a[0] is by itself sorted Pass2: a[1] is inserted either before or after a[0] so that a[0], a[1] is sorted Pass3: a[2] is inserted into its proper place in a[0], a[1]. It continues on and on until all the elements are sorted by inserting each element at its position. Example: `

void selsort(int p[], int n) { int i, pass, min, min_idex, temp; for(pass=0;pass<n-1;pass++) { for(min_ide=pass,i=pass+1;i<n;i++) { if(p[i]<p[min_idx]) min_idx=i; if(pass!=min_idx) { temp=p[min_idx]; p[min_idx]=p[pass]; p[pass]=temp; } } }

-∞ 77 33 44 11 88 22 66 55 -∞ 33 77 44 11 88 22 66 55 -∞ 33 44 77 11 88 22 66 55 -∞ 11 33 44 77 88 22 66 55 -∞ 11 33 44 77 88 22 66 55



Implementation: 4. Write about the Quick sort? Quick sort is a popular sorting method. The name comes from the fact that quick sort can sort a list of elements faster than any other sorting algorithms. The basic strategy of quick sort is to divide and conquer. Hence quick sort is also called partition exchange sort. Suppose an array ‘x’ is stored in memory then take the first element, the first job is placing the first element in its proper position after the array is sorted. To do this, start accessing the elements after key element and elements from the last. Continue until the swap case is attained. When both the conditions are false then, swap the elements Continue until J<=i Example: 40 30 10 50 70 60 90 20 80 66

-∞ 11 22 33 44 77 88 66 55 -∞ 11 22 33 44 66 77 88 55 -∞ 11 22 33 44 55 66 77 88

void insertsort(int p[], int n) { int pass, i, temp; for(pass=2;pass<=n;pass++) { temp=a[pass]; for(i=pass-1;temp<a[i];pass++) a[i+1]=a[i]; a[i+1]=temp; } }

a[i]<a[k] , a[j]>a[k]

(a[i] a[j])



Pass1: Pass2: Pass3: Resultant vector: 10 20 30 40 50 60 70 80 90 Implementation:

40 30 10 50 70 60 90 20 80 66 40 30 10 20 70 60 90 50 80 66 20 30 10 40 70 60 90 50 80 66

20 30 10 40 70 60 90 50 80 66

70 60 66 50 80 90 50 60 66 70 80 90

20 30 10 40 50 60 66 70 80 90 20 10 30 40 10 20 30 40

void quicksort(int a[],int lb,int tub) { Int x; if(ub>lb) { x=split(a,lb,ub); Quicksort(a,lb,x-1); Quicksort(a,x+1,ub); } }



5. What is stack? Write different operations performed on stack? A stack is a linear structure in which items are added, removed from one end. Examples of stacks are a stack of dishes, a stack of coins and a stack of chairs. Where items are added and removed only from the top. It is called last in first out [LIFO]. Definition:- “A stack is a list of elements in which element are inserted, deleted only at one end called top of stack”. The elements are removed from a stack in the reverse order to the order of insertion. Top is a pointer which always points to the top element of the stack. Inserting an element at the top is called push. Deleting an element from the top of the stack is called pop. Displaying an element at the specified position from the top is called ‘peep’. Changing of such elements is called change. Displaying elements from the top to the first is called display. When there are no elements in the stack. Then the state of stack is called ‘stack underflow’. When the stack is filled with the elements then the state of stack is called ‘stack overflow’.

int split(int a[], int lb, int ub) { int key, p, q, t; key=lb; p=lb+1; q=ub; while(p<=q) { while(a[p]<a[key]) p++; while(a[q]>a[key]) q--; if(q>p) { t=a[p]; a[p]=a[q]; a[q]=t; } } t=a[key]; a[key]=a[q]; a[q]=t; return q; }



Operations on stack:- The following operations are performed on stack. 1. Push 2. Pop 3. Change 4. Peep 5. Display. 1. Push operation:- Adding a new element to the top of the stack is called push operation. While performing the push operation, follow the following algorithm. 1. [Check for stack over-flow] if top=MAX-1 then write ‘stack overflows’ return 2. [Increment the top pointer by one] Top<-top+1 3. [Store the element at the top] S[top]=x 2. pop operation: Removing an element from the top of the stack is called pop operation. While performing the pop operation follow the following algorithm. 1. [Check for stack under flow] if (top=-1) then write ‘stack under flow’ return null. 2. [Decrement the top pointer]

Push(5)

5

Push(7) Push(8) Push(9) Push(6)

5 7 8 9 6

Push(15) Stack over flows

5 7 8 9 6

Pop() 6

5 7 8 9

Pop() Pop() Pop() Pop() 9,8,7,5

Pop() Stack under flows



Top top-1 3. [Return formal top element] return s[top+1] 3. Peep operation:- Displaying an element at the required position is called “peep” operation. While performing the peep operation follow the following Algorithm 1. [Check for the stack under flow] if (top=-1) then write ‘stack under flow’ return null. 2. [Check for valid position] if top-pos+1<0 write ‘improper position’ return null 3. [Return element at the required position] return s[top-pos+1] 4. Change operation:- Changing an element at the required position is called change. Check for the stack underflow. While performing the change operation follow the following algorithm. 1. [Check for the stack under flow] if (top=-1) then write ‘stack under flow’ return null. 2. [Check for valid position] if top-pos+1<0 write ‘improper position’ return null 3. [Change the element at the pos] s[top-pos+1] x 6. What is queue and explain different operations performed on queue? Applications: A Queue is a linear data structure where addition of new element takes place at the end of the queue, deletion takes place from the front. Queue’s applications are common in the field of computer sciences. For example, there may be Queue of tasks waiting to print by the printer; number of files may be waiting to write on the hard disk and number of applications which are waiting to be processed by the processor. Queue



works on the principle of FIFO (First In First Out). Where the first item added to the queue is the first item to get remove. Definition: “Queue is a linear data structure stores multiple elements. New elements are added at the rear end, elements are deleted from the front end. To perform the Queue operations two pointers that is the front and rear are used”. The front pointer always points the front elements of the queue. Rear pointer points the rare elements of the Queue. When the Queue has no elements the front elements then the state of the Queue is called Queue underflow. When the rear is said to the max-1 then Queue doesn’t allows any new elements to add. The state is called Queue overflow. Queue works on the principle of FIFO (First In First Out). The following operations can be performed on the queue. 1. Adding 2. Deleting Adding: Adding a new element to the end of queue is called add operation. Follow the following algorithm to perform add operation. 1. [Check for over flow] if rear=MAX-1 then write ‘Queue overflows’ return

Add(5)

5

Add(6) Add(8) Add(3) Add(2)

5 6 8 3 2

Add(9) over flow

5 6 8 3 2

Delete() 2

5 6 8 3

Delete() Delete() Delete() Delete() 3,8,6,5

Delete() Under flow



2. [Increment rear pointer] R R+1 3. [Insert the element] Q[R] Y 4. [Set the front pointer adding the first element] If F=-1 then F 0 Return. Removing: Removing an existed element from the front of the queue is called delete operation. Follow the following algorithm to perform delete operation in a queue. 1. [Check for queue under flow] If F=-1 then write ‘Queue underflows’ return null 2. [Store the front element] x Q[front] 3. [Set the front pointer properly] If front=rear then front rear -1 else front front+1 end if 4. [Return the former front element] return x. 7. What is circular queue? Write the operations on circular queue?

A Queue is a linear data structure where addition of new element takes place at the end of the queue, deletion takes place from the front. The normal Queue implemented using an array suffers from limitation. In a simple Queue implantation there is a possibility that the Queue is reported as full when the rare is set to n-1, though there are free spaces to take more elements.

3 2

Add(5)

Queue overflows

5 3 2



To overcome this limitation, we can implement the Queue as a circular Queue. Here when the rear pointer reaches n-1 then, the next element is stored in the first slot of the array. The Queue would be reported as full only when all the slots in the array are filled with the elements. Operations on circular Queue:- Like normal Queue all the operations performed on normal queue can be performed on circular Queue. The common operations performed on a circular queue are 1. Adding (insert) 2. Remove (delete) 3. Display 1. Adding:- Adding a new element to the circular Queue is called insert. When the C.Q. is with the full of elements then display Queue overflows, if not increment the rare pointer by one and insert the element at the rare pointer. If rare pointer is n-1 then set it to the beginning of the Queue. Algorithm:- 1. [Check for Queue Over flow]

if (front=0 and rear=MAX-1) or (front=rear-1) then write(‘Queue over flow’) return

2. [Reset the rear pointer] if rear=MAX-1 then rear0

else rear rear+1 end if

3. [Insert the element] Q[rear] x

4. [Reset front pointer] if front=-1 then front front+1

2. Delete:- Removing an element from the front of the Queue is called ‘Delete’ return the front element of the Queue and set the front pointer. If front pointer is at n-1 then set it to the beginning of the Queue, otherwise increment the value of front pointer by one. When both the front and rare pointers are same then set them to ‘-1’. When the Queue has no elements then display the message ‘underflows’. 1. [Check for Queue underflow]



if front=-1 then write (‘Queue underflow’) return null

2. [Delete the element] x Q[front]

3. [Increment the pointer] If front=MAX-1 then front 0 else if front=rear then front rear -1 end if

4. return x 8. Write about the double ended Queue? (Or) Write about the DEqueue? The word DEqueue is a short form of double ended queue. It is a linear data structure in which items added and removed from both the ends. In other words it is a combination of both stack and queue. According to the insertion and deletion of elements DEqueue can be classified into

1. IRDEqueue 2. ORDEqueue

IRDEqueue It is a double ended queue where adding a new element is done at the rear of the queue, deletion is done from both the ends. ORDEqueue It is a double ended queue where deleting an element is done only from the front end but, adding a new element is done from both the ends. So it is called output restricted double ended queue.

r

f

40 23 50

insert

delete delete



9. Write about the priority queues? A priority queue is a collection of elements, where elements are stored according to the priority levels. The order in which the elements should get added or removed is decided by the priority of the elements. 1. The element with higher priority is processed before any element of lower priority 2. If there are elements with the same priority then the element added first in the queue would get processed first. Priority queues are used for implementing job scheduling by the operating system, where jobs with higher priorities are to process first. According to the priority of elements priority queues can be classified into

1. Ascending priority queues 2. Descending priority queues

In ascending priority queues elements are arranged in ascending order. In descending priority queues elements are arranged in descending priority. In both the cases first element is always deleted and all other elements are re-arranged so that first element is always at ‘0’. New element is added at rear. 1. Adding 2. Removing:

r

f

40 23 50

insert insert

delete

Add(50) Add(30)

r -1

f

Add(10) r

f

10 30 50

r

f

10 30 50

remove 10

f

30 50

r



10. Write about the parsing of arithmetic expression? Infix expression: When the operators are placed with the operands, then the expression is called an infix expression. Normally we give infix expression to the compiler. The compiler coverts the infix expression into the postfix or prefix expression. And then expression will be evaluated. Postfix expression: When the operators are written as postfix to the operands then the expression is called postfix expression. Prefix Expression: When the operators are written as prefix to the operands then the expression is called prefix expression. Example: Infix expression: (a+b)*(c+d) Postfix expression: ab+cd+* Prefix expression: *+ab+cd Parsing of Expression: Evaluating an arithmetic expression is called parsing an expression. It can be done two ways

1. Postfix 2. prefix

Parsing of postfix expression Algorithm:

1. Input the postfix expression 2. Scan the expression from left to right 3. During our scanning

1. if you find an operand then push it onto the stack, continue scanning

2. if you find an operator then pop the top 2 elements from the stack and allow your operator to work on these operands, push the intermediate result onto the stack and continue scanning

3. When you reach the end of the string. There should be only one element in the stack. Pop this element to get the value of post fix expression.

Parsing of prefix expression: Algorithm:

1. Input the prefix expression 2. Reverse the prefix expression 3. Scan the expression from left to right 4. During our scanning



a. if you find an operand then push it onto the stack, continue scanning

b. if you find an operator then pop the top 2 elements from the stack and allow your operator to work on these operands, push the intermediate result onto the stack and continue scanning

c. When you reach the end of the string. There should be only one element in the stack. Pop this element to get the value of prefix expression.

11.What is linked list? State the advantages of list over arrays? (Or) Write the construction of a linked list? Disadvantages of Arrays (Static list):

For storing similar data in memory we can use either an array or linked list. Array is a set of elements of the same type stored in consecutive memory allocation. The memory allocation of array happens during the compilation of the program. Hence an array cannot be expanded or compressed. Due to the lack of flexibility in arrays stacks, Queues implementing with arrays suffers from overloading. New elements may not be inserted and the old elements may not be deleted.

All the above disadvantages of array can be overcome by the complex data structure linked list.

A linked list can grow or shrink in size during its life time. Linked list does not need consecutive memory allocations, because individual nodes are created in different memory allocations but, logically linked. Insertion and deletion of elements can be easily done with out shifting the position of elements. Linked list (Dynamic List):

Linked list is a very common data structure often used to store similar data in memory. The individual elements are stored in different memory allocations but, still bound together by referring to each other. The order of elements is maintained by explicit links between them. Every element in a linked list is considered as a node. Each of which stores two items of information. That is the data and the link of other node. Here the link is a pointer or an address that indicates the location of next node explicitly. The NULL stored in the last node indicates that it is the last node in the list. Always the reference of the first node is stored in a head pointer.



Append a node: Adding a new element at the end of the list is called ‘append’

to append a node follow the following algorithm. 1. create a new node 2. Store the data into the data part, Null into the link part. 3. If the head pointer has the null value, then store the reference of new

node in the head. 4. Otherwise find the last node and store the reference of new node into

the link part of the last node. Case 1:

Case 2:

Traversing the list: Visiting all the nodes of a list from head to tail is called traversing. To traverse the list, follow the following algorithm 1. If the head is stored with null then display that, the list is empty. 2. Otherwise traverse the list from head using link of each node. Case 1: Case2:

Display() 10 30 45

head 10 30 50 null

null

append(50)

Head

20 50

null Head

append(20)

Head

20 null

Display()

head

List is empty

null



Implementation:

class Node { int data; Node link; } class List { Node head; List() { head=null; } void append(int x) { Node temp, p; temp=new Node(); temp.data=x; temp.link=null; if(head==null) head=temp; else { for(p=head;p.link!=null;p=p.link); p.link=temp; } } void display() { Node p; if(head==null) System.out.println(“List is empty”); else { for(p=head;p!=null;p=p.link) System.out.println(“\t”+p.data); } } }

class Demo { public static void main(String args[]) { Node n=new Node(); n.append(23); n.append(45); n.append(80); n.append(72); } }



12. Write the procedure to delete a node? Deleting a specified element from the list is called delete operation. The following operation is used to perform delete operation.

1. accept the element 2. Search for the given element with in the list. 3. If element is not existed then display proper message. 4. Other wise store the link part of specified node into the link part of

previous node. 5. Delete the specified element.

Case 1: Case 2: Case 3:

Head null

delete(10); no elements are existed

Head

20 50 null

Head

delete(20)

20 50 null

Head 20 40 60 NULL

Delete(40)

Head 20 40 60 NULL



Implementation: 13. Write about different types of Linked Lists? Linked list is a very common data structure often used to store similar data in memory. The individual elements are stored in different memory allocations but, still bound together by referring to each other. The order of elements is maintained by explicit links between them. Every element in a linked list is considered as a node. Each of which stores two items of information. That is the data and the link of other node. Here the link is a pointer or an address that indicates the location of next node explicitly. According the construction of lists, linked lists can be classified into header linked lists and doubly linked lists. Header linked lists: A header linked list is a linked list which always contains a special node called the header node, at the beginning of the list. The following are two widely used header lists. 1. Grounded header list: It is a header list where the last node contains the null pointer. The name of which has come from the fact that the null pointer is considered as ground in case of null.

void del(int x) { Node p,pre; if(head==null) System.out.println(“List is empty”); else if(head.data==x) { p=head; head=head.link; } else { for(p=head;p!=null;pre=p,p=p.link) if(p.data==x) break; if(p==null) System.out.println(“No such element is existed”); else pre.link=p.link; } }

Head 20 40 60 NULL



2. Circular header list: In the circular header list last node contains the address of the first node. But, not grounded. Circular linked lists are frequently used instead of ordinary linked lists. Because many operations are mush easier to state and implement using header list. The reasons are,

1. The null pointer is not used and hence all pointers contain valid addresses.

2. Every node has a predecessor. So the first node may not request a special case.

*Doubly linked list: Linked list is a linear data structure which is used to store multiple values belongs to same type. A linked list is build with number of nodes logically linked with each other by storing the address of next node into current node. Each node has two parts that is the data and link. The data part stores the actual information and the link pointer stores the reference o next node. Head is the pointer which stores the reference of first node. It is stored with null value if the list is empty. Disadvantages of singly linked lists:

1. It is not possible to traverse the list in reverse order. 2. We can not perform search operation from middle of list in any of

directions. 3. To make the list more flexible a doubly linked list is designed.

Definition: A doubly linked list is a linear data structure used to store multiple values in a logically consecutive memory allocation. Each node in a doubly linked list has three parts that is the left pointer which stores the previous node reference, data which stores the actual information and right pointer which stores the reference of right pointer. There are two pointers called first, last. Which are used to store the reference of first and last node. Example:

Head 20 40 60

null null

first last

append(10);



14. What is tree and explain different trees? A tree is a non-linear data structure that represents hierarchical relationship between individual data elements. Trees encounters in every life that is in real and computer applications. In tree structure every node may point number of other nodes. Tree is a very flexible data structure used in number of applications. General tree: A tree is an acyclic graph has one node at the top is called root. It is at the level ‘0’. Some nodes will be at the level ‘1’ called branch nodes. The level of any node is the length of its path from the root. In a tree if a node has any number of sub nodes then the tree is called general tree. Binary tree: Although the nodes in a general tree contains any number of pointers to the other tree nodes, a large number of data structures have at the most two pointers to the other tree nodes. This type of tree is called binary tree.

last first null 10 null

append(20);

first

null 10 20 null last

A

B C

D E F

A

C

D E F

B



Strictly binary tree: A binary tree is said to be strictly binary tree if every non-leaf node has two sub nodes or two sub trees. Complete binary tree: If all the leaf nodes of a strictly binary tree are at the same level, then the tree is called complete binary tree. Binary search tree: If, in a binary tree all the elements in left sub tree of a root are less than the value of root, all the elements in right sub tree of a root are greater than the value of root, then the tree is called binary search tree.

6

3 5 7 9

4 8

A

D E F G

C B

A

C

D E

B



15.What is binary search tree (BST)? Explain the operations on tree? A binary search tree is a binary tree with some special properties. The data values of all the nodes in the left sub-tree are less than that of the root. The data values of all the nodes in the right sub-tree are greater than that of the root. The left sub-tree and right sub-tree are themselves binary search trees. Construction: A binary tree can be build using the linked list. Every node has three parts. That is the data, left and right. The left pointer has the reference of left node and right pointer has the reference of right node. If the node is a leaf node then both the left, right stored with null. The following algorithm is used to construct the BST. The root node reference is stored in pointer called head. 1. Create a node and store the data init 2. Store the null values in both the left, right pointers of the new node. 3. If the tree is empty then store the reference of new node into the head pointer. 4. Otherwise, using the head pointer by traversing either left or right find the parent node address to the new node. 5. Add the new node to the binary tree. Example:

Traversals: Visiting selected or all the nodes in a pre-defined order is called traversing. The primary reason for visiting a node is to process the contents of the nodes. The tree can be traversed using three methods.

Linked List Representation

6

3 5 7 9

head

6

6 6

6 6 6 6

8 4



Pre-order traversal Post-order traversal In-order traversal Pre-order traversal: It is known as depth-first traversal. In this traversal the root node is visited prior to the left and right nodes in a sub tree. The rule for pre-order traversal is

1. visit the root-node 2. then visit the nodes in the left sub-tree in pre-order 3. finally visit the nodes in the right sub-tree in pre order

Post-order traversal: It is known as breadth-first traversal. In this traversal the root node is visited after the left and right nodes in a sub tree. The rule for pre-order traversal is

1. visit the node in the left sub-tree in post order 2. then visit the node in the right sub tree in post order 3. finally visit the root node

In-order traversal: In this traversal the root node is visited in between the node in left and right sub-trees. 1. Visit the node in the left sub-tree in in-order. 2. Visit the root node. 3. Finally visit the nodes in the right sub-tree in in-order Example:

6

3 5 7 9

Pre-order: 6 4 3 5 8 7 9 Post-order: 3 5 4 7 9 8 6 In-order: 3 4 5 6 7 8 9

8 4



16. What is a graph? Explain the types of graphs? Graphs are the non-linear data structures. It describes certain type of relation ship among the data items. Tree is also a kind of graph where data items have parent child relation ship. A general graph is a structure that represents a less restrictive relation ship between data items. Example: A common example for a graph is a collection of cities and roads between them. Definition: A graph G is a collection of two sets V and E. V is the collection of vertices or nodes. E is the collection edges. Where, edge is an arc which connects two nodes or vertices.

G=(V,E) V(G)=(v0,v1,,……..vn) E(G)=(e0,e1,………en)

Types of graphs: Graphs can be classified as both directed and undirected. If every edge in a graph G is marked by a direction then the graph is called direct graph. It is often called as digraph. If directions are not marked for any edge then the graph is called un-direct graph. Direct graph: If every edge i,j in E(G) of a graph is marked by a direction from i to j then the graph is called direct graph. A directed graph is often called as digraph. In the graph specified bellow pairs of vertices (1,2) and (2,1) will represent two different edges where as in un-direct graph both will be treated as a single edge.

1

2

3

Direct graph

G=(V,E) V(G)={1,2,3} E(G)={(1,2),(2,1),(3,2)}



Un-direct graph: If directions are not marked for any edge then the graph is called un-direct graph. A normal tree or a binary tree can be a perfect un-direct graph. Applications of graphs: Graphs are use-full data structures for modeling various kinds of processes or structures. Cities and high-ways form a graph. Components on the circuit board form a graph. An organic chemical compound can be consisted as a graph with the atoms as vertices and the bonds between them as edges. 17. Write about the representation of graphs? According to the field of computer sciences graphs can be represented in two ways.

1. Adjacency matrix 2. Adjacency list

Adjacency Matrix: A graph may be direct or un-direct can be conveniently represented by an adjacency matrix. Which is also called an incidence matrix. A graph contains ‘n’ node can be represented by a square matrix containing ‘n’ rows and ‘n’ columns. The matrix is formed by placing ‘1’ in the ith row and ith column of the matrix, if there is an edge between the nodes i&j of the graph. Otherwise places a ‘0’ Example:

G=(V,E) V(G)={1,2,3,4} E(G)={(1,2),(1,3),(1,4),(2,3),(2,4),(3,4)}

1

3

4

2

Un-direct graph



Adjacency list: The ‘n’ rows of an adjacency matrix can be represented as ‘n’ listed lists. There is one list for each node in the graph ‘G’. Each list will contain adjacent nodes. Each node has two fields. That is vertex and link. The vertex field of a node will contain the nodes that are adjacent to the node. The adjacency list can be easily build using adjacency matrix.

1

2

3

1

3

4

2

Adjucent Matix

1 2 3 4 1 0 1 1 1 2 1 0 1 1 3 1 1 0 1 4 1 1 1 0

1 2 3 1 0 1 0 2 1 0 1 3 0 0 0

1

2

3

Adjucent Matix

1 2 3 4 1 0 1 1 1 2 1 0 1 1 3 1 1 0 1 4 1 1 1 0

Adjucent List

2 3 4 null

1 3 4 null

1 2 4 null

1 2 3 null



18. Write about the graph traversals? Visiting all the nodes in a graph systematically is called traversal. In all the practical applications of graphs, there is a need to visit all the nodes in a systematic order. There are two popular ways of visiting nodes of a graph i.e., 1. Depth-First search. 2. Breadth-First search. Depth-First search:- The depth first search algorithm is almost equal ant to pre-order traversal in trees. In graph traversal there are two differences which do not appear in trees. Because the graph contain cycles, algorithm reaches the same node for the second time. The graph may not be connected, so the traversal algorithm may fail to reach all vertices from a single starting point. Algorithm:- 1. Choose any node in the graph. Design it as the search node and mark it visited. 2. Find a node that is adjacent to search node using the adjacency matrix of the graph. This node must not have been visited before. Designate this as the new search node & mark it is as visited. 3. Repeat step-(2) using new search node; When all the adjacent nodes to a search nodes have been visited, return to previous search node and continue from there. 4. When a return to the previous search node in step-3 is impossible. Then search from the originally chosen search node is completed. 5. If the graph still contains unvisited nodes choose any node that has not been visited and repeat step-(1) to step-(4). This algorithm is called a depth-first search because the search continues progressively deeper in a recursive manner. Adjacent matrix:

0 2

1 3

4

0 1 2 3 4 0 0 1 1 0 0 1 0 0 1 0 0 2 0 0 0 0 0 3 0 1 1 0 1 4 0 0 1 0 0



Adjacent: Breadth-First search:- Essentially the breadth-first search begins at a given node and then proceeds to all the nodes directly connected to that node. 1. Begin with any node, mark it as visited. 2. Proceed to the next node having an edge connected to the node in step-(1) mark it as visited. 3. Come back to the node in step-(1) descend along an edge towards an unvisited node and mark the new node as visited. 4. Repeat step-(3) until all bodes adjacent to the node in step-(1) have been marked as visited. 5. Repeat step(1) to(4) starting from the node visited in (2) then starting from the node visited in step-(3) in the order visited. Keep this up as long as possible before starting a new scan.

0:1,2 1:2 2: 3:1,2,4 4:2

Path1:0,1,2 Path2:3,4

F B C

E G

A

D

J K

A F C B

J K

E J

D G E

F C B D

C B D G



Programs to refer: 1. stacks using array 2. queue using array 3. circular queue 4. Linked list operations. 5. Doubly linked list implementation. 6. Binary Search tree construction

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