introduction a java program to print “fibonacci number” series given integer n. the fibonacci...
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CSC 308 2.0
System Development with Java
Budditha Hettige
Department of Statistics and Computer Science
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Introduction
Budditha Hettige
JAVA
• Is a programming language created by James Gosling from
Sun Microsystems in 1991
• Is a general-purpose, class-based, object-oriented
Programming language
• is intended to let application developers
“write once, run anywhere.”
• Current version Java SE 7 (July 28, 2011)
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Java cont…
• Java programming language consists
– Java compiler:
Java compiler translates Java coding into
byte-code
– Java virtual machine(JVM)
Java virtual machine interprets this byte-code and runs the program
– Java class libraries
Java Class Library is a set of dynamically loadable libraries that Java applications can call at run time
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Java Virtual Machine (JVM)
Architecture
JAVA Source File (.java)
JAVA Bite code (.class)
Java Compiler Java Compiler
Java Virtual Machine
Java Virtual Machine
Memory Manager Memory Manager
Byte code Verifier Byte code Verifier
Interpreter Interpreter
Java API Java API
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Characteristics
Java has the following properties
• Platform independent
• Object-orientated programming language
• Strongly-typed programming language
• Interpreted and compiled language
• Automatic memory management
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Simple Java Program
• A class with a main Method
public class FirstProgram { public static void main(String[] args) { System.out.println("Hello World"); } }
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Requirements for Class name
• Class name must begin with letter of the
alphabet
• Contains only letters, digits, underscores or
dollar sign
• Cannot be a language reserved keywords
(public, class etc)
• Name cannot be following values (true, false
or null)
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Java Keywords
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Java Class name standard
• Begin with uppercase letter
• No spaces
• Emphasizes new word with an initial uppercase letter
Example
EmployeRecords
Student
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Your first Java program
• Open a text editor (text pad, Notepad etc.)
• Type the following sample
• Save program as “FirstProgram.java”
public class FirstProgram { public static void main(String[] args) { System.out.println("Hello World"); } }
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Your first java program
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Compile and RUN
• Using command prompt go to the place where in your
java file
• To Compile: type javac <space><fileName>
Javac FirstProgram.java
• To Run: type java<space><fileName>
Java FirstProgram
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Java Programming with IDE
• IDE : integrated design environment
• consists of
– source code editor
– compiler and/or an interpreter
– build automation tools
– Debugger
– Construction of a GUI
– Class browser
– Object inspector
– Etc.
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Programming IDEs
• Eclipse
Eclipse is a multi-language software development environment
http://www.eclipse.org/
• Netbeans
http://netbeans.org/
• Microsoft Visual Studio
http://www.microsoft.com/visualstudio/en-us
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Java Programming
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Comments
• Comments are nonexecuting statements
• Line comments // line comments
• Block comments
/*
block comments
*/
• Javadoc comments
/**
Javadoc comments
*/
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Print Output on Command window
• Function
– System.out.println(“Some Text”);
– System.out.print(“Some Text”);
• Example
public class FirstProgram { public static void main(String[] args) {
System.out.println("Hello World"); } }
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Escape Sequences
• A character preceded by a backslash (\) is an escape sequence
• has special meaning to the compiler
Escape Sequence Description
\t Insert a tab in the text at this point.
\b Insert a backspace in the text at this point.
\n Insert a newline in the text at this point.
\r Insert a carriage return in the text at this point.
\f Insert a formfeed in the text at this point.
\' Insert a single quote character in the text at this point.
\" Insert a double quote character in the text at this point.
\\ Insert a backslash character in the text at this point.
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ASCII art with JAVA
• ASCII art is a graphic design technique that uses computers
for presentation and consists of pictures pieced together from
the 95 printable (from a total of 128) characters defined by the
ASCII Standard from
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ASCII art with JAVA cont..
System.out.println(" ");
System.out.println(" @ @ @ ");
System.out.println(" @ @ @ @ ");
System.out.println(" @ @ @ ");
System.out.println(" \\|/ ");
System.out.println(" | | | ");
System.out.println(" | | | ");
System.out.println(" | | | ");
System.out.println(" | | | ");
System.out.println(" ( ) ");
System.out.println(" ^^^^^ ");
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Java Data types
• The eight primitive data types supported by the Java
programming language
Keyword Description Size/Format
byte Byte-length integer 8-bit two's complement
short Short integer 16-bit two's complement
int Integer 32-bit two's complement
long Long integer 64-bit two's complement
float Single-precision floating point 32-bit IEEE
double Double-precision floating point 64-bit IEEE
char A single character 16-bit Unicode character
boolean A boolean value (true or false) true or false
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limits of integer in java
type Size Range
name bytes bits minimum maximum
byte 1 8 -128 +127
short 2 16 -32,768 +32,767
int 4 32 -2,147,483,648 +2,147,483,647
long 8 64 -9,223,372,036,854,775,808 +9,223,372,036,854,775,807
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Variables
• Declaration
DataType <space> VaribaleName
• Example: int count;
int studentAge = 0;
float GPA = 3.56;
System.out.println(“Student GPA : ” + GPA);
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Input from Keyboard
• Use Scanner
– Import java.util.Scanner;
import java.util.Scanner;
– Create a Scanner object to Scan input from command window
Scanner input = new Scanner(System.in);
– Read value from keyboard
Use methods (nextInt()- interger, nextLine()- String, nextFloat()- float, nextDouble()- double etc.)
value = input.nextInt();
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Example 1:
• Create a java program to read 2 integer values and
print the average.
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Example 1: Solution import java.util.Scanner; public class FundamantalApp { public static void main(String[] args) { Scanner input = new Scanner(System.in); int value1, value2; float avg; System.out.println("Enter value1 :"); value1 = input.nextInt(); System.out.println("Enter value1 :"); value2 = input.nextInt(); avg = (value1 + value2)/2; System.out.println("Average is "+ avg); } }
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Output Formatting
• Use printf function
System.out.printf(“Values %d”, value1);
Can insert with and justification for the format
System.out.printf("%5d", 0);
5 field width
System.out.printf("%-5d", 0); - Left justify,
System.out.printf("'%.2f'", 10.3456);
Two positions after the decimal
Conversion type Conversion type
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Format specifies
%c character
%d decimal (integer) number (base 10)
%e exponential floating-point number
%f floating-point number
%i integer (base 10)
%o octal number (base 8)
%s a string of characters
%u unsigned decimal (integer) number
%x number in hexadecimal (base 16)
%% print a percent sign
\% print a percent sign
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Method Declaration
• Method declaration contains the following
– Optional access modifiers (Public, private, protected, static)
– Return type (void, int, char …)
– Name
– Open parenthesis
– Optional list of arguments
– A close parenthesis
• Example
– public static void printName(){}
– public int calulateAverage(int x, int y){}
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Method Calling
public static void main(String[] args) { float avg;
printName(); Avg = calulateAverage(10,34);
}
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Classes
• Create a class with method (No main method)
class student
{
public void printName()
{
System.out.println("I am a Student class");
}
}
• Create a public all with main method
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Classes contd..
• Create a class object
student st = new student();
• Call the method through the object
st.printName();
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Sample code class student
{
public void printName()
{
System.out.println("I am a Student class");
}
}
public class FundamantalApp
{
public static void main(String[] args)
{
student st = new student();
st.printName();
}
}
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if-then-else Statement
• Syntax if (Condition) { statement(s) } else { statement(s) }
• Example if (isMoving)
{
currentSpeed--;
}
else
{
System.err.println("The bicycle has already stopped!");
}
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Loops
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For Loop
• Syntax for (initialization; termination; increment)
{
statement(s)
}
• Example
for(int i=1; i<11; i++)
{
System.out.println("Count is: " + i);
}
Count is: 1 Count is: 2 Count is: 3 Count is: 4 Count is: 5 Count is: 6 Count is: 7 Count is: 8 Count is: 9 Count is: 10
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Example
1. Write a java program to print the following figure
a) * b) 1
** 12
*** 123
**** 1234
***** 12345
2. Create a java program to print “Fibonacci number” series given integer n. The Fibonacci
number has the following integer sequence: (use an array to store the number series)
0, 1, 1, 2, 3, 5, 8, 13, 21, 34, 55, 89, 144…
Mathematically
Fn = Fn-1 + Fn-2 Where (F0 = 0, F1 = 1)
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Answers
a) for(int i=1; i<= 5 ;i++)
{
for(int j=0; j < i; j++)
{
System.out.print("*");
}
System.out.println("");
}
b) int limit = 20; long[] series = new long[limit]; series[0] = 0; series[1] = 1; //create the Fibonacci series and store it in an array for(int i=2; i < limit; i++) { series[i] = series[i-1] + series[i-2]; } //print the Fibonacci series numbers System.out.println("Fibonacci Series upto " + limit); for(int i=0; i< limit; i++) { System.out.print(series[i] + " "); }
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While Loop
• Syntax
while (expression)
{
statement(s)
}
• Example
int count = 1;
while (count < 11)
{
System.out.println("Count is: " + count);
count++;
}
Count is: 1 Count is: 2 Count is: 3 Count is: 4 Count is: 5 Count is: 6 Count is: 7 Count is: 8 Count is: 9 Count is: 10
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Example
Create a java program to identify the given number is
Palindrome number or not.
– Read number as a interger
– Find the bnumber is Palindrome or not
– Print the results
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Answers
int number = orgnumber;
int reversedNumber = 0;
int temp=0;
//reverse the number
while(number > 0)
{
temp = number % 10;
number = number / 10;
reversedNumber = reversedNumber * 10 + temp;
}
if(orgnumber == reversedNumber)
System.out.println(orgnumber + " is a palindrome number");
else
System.out.println(orgnumber + " is not a palindrome number");
}
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Do-while Loop
• Syntax
do
{
statement(s)
} while (expression);
Example int count = 1;
do {
System.out.println("Count is: " + count);
count++;
}
while (count <= 11);
Count is: 1 Count is: 2 Count is: 3 Count is: 4 Count is: 5 Count is: 6 Count is: 7 Count is: 8 Count is: 9 Count is: 10
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Loops comparation
For while do-while
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Exercise do-while loop
• Using do-while loop, create a java program to display the
selected option in the following menu;
[1] insert data
[2] read data
[3] print data
[4] Exit the program
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Switch Statement
• The switch statement can have a number of possible execution
paths
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Exercise
• Create a java method to calculates the number
of days in a particular month: – 1, 3, 5, 7, 8, 10, 12 – 31 days
– If current year is divide by 4 and divide by 100 or divide by
400 is leaf year (29 days for February)
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Answer
int month = 2;
int year = 2000;
int numDays = 0;
switch (month)
{
case 1:
case 3:
case 5:
case 7:
case 8:
case 10:
case 12: numDays = 31;
break;
case 4: case 6: case 9: case 11: numDays = 30; break; case 2: if ( ((year % 4 == 0) && !(year % 100 == 0)) ||(year % 400 == 0) ) numDays = 29; else numDays = 28; break; default: System.out.println("Invalid month."); break; } System.out.println("Number of Days = " + numDays);
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Array
• Array declaration
Type [] Name = new type[Count];
• Example :
int[] anArray = new int[10];
anArray[0] = 40;
anArray[0] = 40;
int[] anArray = {100, 200, 300, 400, 500};
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2D Array
• Declaration
Type [] [] name; name = new type[Count][];
name[0] = new type[Num];
name[1] = new type[Num];
. . . name[Count-1] = new type[Num];
• Example:
int[][] data; data = new int[10][]; data[0] = new int[5]; data[1] = new int[20];
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Example
Create a menu driven java program to do the following
– Create a class namely student, to store the following student information
student(indexNo, name, address, email, gender)
– Use an array to implement the program (Assume that, maximum number of student in the class 10)
– Your menu should have the following options
Department information system
[1] Enter new student
[2] Change student information
[3] Delete an existing student
[4] Print student information
[5] Exit the program
– Your program should have the following features 1. when you are going enter a new student, If it is already 10 students are in the
array print the message “no any space available for enter new student”,
2. After a student deleted, system give a way to insert a new student
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