2 starting javaprogramming

7/28/2019 2 Starting JavaProgramming

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By: De Rosal, Ign. Moses S.

http://docs.oracle.com/javase/
http://docs.oracle.com/javase/http://docs.oracle.com/javase/


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ContentJava Structure

Compile & Running Program

Language Basics

Variables Data Types

Operators

Scanner Class

Control Flow

Loopinghttp://docs.oracle.com/javase/


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JAVA STRUCTURE



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Java Program Structure

Java must have a public class

Start with public static void main(String[]args)

There are two kinds of java programming: GUI-based

Text-based

Syntaxto declareclass:[modifier] [class] class_name{

}


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Example

modifier class_name

main program


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Details Halo.java

Defineclass andmodifier

That can be compiledand executed by theJVM


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Details (2) Halo.java

Main program and first time it is run by JVM

Public : one of modifier Static : type of method

Void : no return value

Main : main method

String : type of argumen Args: Array of argumen

which can be added whilerunning


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Details (3) Halo.java

Function to display text in console

println after display text produce a new line

just display text


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COMPILE AND RUNNING



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Compiling Program

Complie javacname_file.java


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Compiling Program

Compliewill produce class file


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Running Program

Running java class_file without.class


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LANGUAGE BASIC



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Variables

The Java programming language isstatically-typed, which means that all variablesmust firstbe declared before they can be used.

The Java programming language defines thefollowing kinds of variables:

Instance Variables (Non-StaticFields)

Class Variables (StaticFields)

Local Variables

Parameters


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Naming Variables

Variable namesarecase-sensitive

Must start with aletter (a-z, A-Z), thedollar sign"$", or theunderscorecharacter _ after the first

character, can be followed bynumbers(0-9). Variable names containdash(-) or space( ).

Beginning with lowercase on the first wordand

uppercase letters in thesecondand subsequentwords.

Also keep in mind that the variable names you choosemust not be a keywordor reserved word.


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Java Language Keywords

abstract continue for new switchassert*** default goto* package synchronized

boolean do if private this

break double implements protected throw

byte else import public throwscase enum**** instanceof return transient

catch extends int short try

char final interface static void

class finally long strictfp** volatile

const* float native super while

* not used

** added in 1.2

*** added in 1.4

**** added in 5.0


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Instance Variables

Can be access with instance class


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Class/Static Variables

Can be access with static class


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Local Variables

declare local variable within method


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Parameters


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Primitive Data TypesData type Length range of values Example

boolean 1 bit 0 and 1 0;

1

byte 8 bit -128 to 127

(-27 to 27)

-5;

10

short 2 byte / 16 bit -32,768 to 32,767

(-215 to 215)

-12,777;

31,578

int 4 byte / 32 bit -2,147,483,648 to 2,147,483,647

(-221 to 221)

-2,107,483,448 ;

2,145,483,638

long 8 byte / 64 bit -9,223,372,036,854,775,808 to

+9,223,372,036,854,775,807.

(-263 to 263)

9,103,372,036,854,775,807

float 4 byte / 32 bit 1.40129846432481707e-45 to

3.40282346638528860e+38

double 8 byte / 64 bit 4.94065645841246544e-324d to

1.79769313486231570e+308d

char 2 byte / 16 bit 0 to 65,535 (unsigned)


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Default Values

Data Type Default Value (for fields)

byte 0

short 0

int 0

long 0L

float 0.0f

double 0.0d

char '\u0000'

String (or any object) null

boolean false


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Operators

Operators are symbols and special characters(mathematics) used in an expression

Example: int x =3;

int y =x;

int z =x * y;

booleanstatus =true;


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Operators (2)


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Operators (3)

ArithmeticOperators

perform addition, subtraction, multiplication, division, andmodulo.

UnaryOperators

requireonlyone operand

perform incrementing/decrementing a value by one,

negating an expression, or inverting the value of a boolean. The Equality and Relational Operators

determine if one operand is greater than, less than, equal to,or not equal to another operand.


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Operators (4)

Conditional Operators

perform Conditional-AND and Conditional-ORoperations on two booleanexpressions.

Bitwise and Bit Shift Operators

To manipulated bit pattern

less commonly used.


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Ex: Unary Operator


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Ex: Bitwise and Bit Shift Operators


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Ex: Bitwise and Bit Shift Operators(2)


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Operator Priority

1. Operator in bracket or parentheses"(...)"

2. Incrementand decrement operators

3. Multiplication and division operators4. Addition and subtractionoperators

5. Bitwiseoperators

Try Out Operator


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Try Out Operator

Change the following program to use assignments operator!!!

T O t O t


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Try Out Operator answer


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CLASS SCANNER



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Class Scanner

A simple text scannerwhich can parse primitive typesand strings using regular expressions.

For example, this code allows a user to read a numberfrom System.in:

Import: java.util.Scanner;


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Class Scanner (2)

nextInt(): to receive integer data type

nextShort(): to receive short data type

nextLong(): to receive long data type nextDouble(): to receive double data type

nextFloat():to receive float data type

nextLine(): to receive string data type

nextBoolean(): to receive booleandata type

Import: java.util.Scanner;

Ex: Class Scanner


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Ex: Class Scanner

Result Ex: Class Scanner


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Result Ex: Class Scanner

Ex: Class Scanner (2)


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Ex: Class Scanner (2)

Result Ex: Class Scanner (2)


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Result Ex: Class Scanner (2)


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CONTROL FLOW STATEMENTS



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Control Flow Statements

Control Flow Statements consist of:

Decision making statements,

if-then executed only if a particular test evaluates totrue

if-then-else

Switch the switch statement can have a number of possibleexecution paths.

Looping statements, and

For

While do-while

Branching statements

Break

Continue return

E IF ELSE


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Ex: IF ELSE

Ex: Switch


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Ex: Switch

T O t D i i M ki


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Try Out Decision Making

StatementsCalculates the number of days in a particular month:

Numberof Daysin February2012=29

Numberof Daysin February2011=28

Numberof Daysin January, March, May, July, August,October, December=31

Numberof Daysin April, June, September, November=30

Clue: use if elseand switch statement

With scanneroutput


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LOOPING



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While Statement

The while statement continually executes a block ofstatements while a particular condition is true.

Its syntax can be expressed as:

Ex: While Statement


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Ex: While Statement


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Do-While Statement

The difference between do-while and while is thatdo-whileevaluates its expression at the bottomof theloop instead of the top.

Therefore, the statements within the do block arealways executed at least once.

Ex: Do While Statement


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Ex: Do-While Statement


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The for Statement

The for statement providesa compact way toiterate over a range of values.

Programmers often refer to it as the "for The general form of the for statement can be

expressed as follows:


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Ex: For Statement


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Ex (2): For Statement


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The break Statement

Thebreak statement has two forms: labeledandunlabeled.

You can useunlabeled in switch statement, or toterminatea for, while, or do-while loop.

You can uselabeled for loops to search for a valuein atwo-dimensional array.

Ex: unlabeled break Statement


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Ex: unlabeled break Statement

Ex: labeled break Statement


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Ex: labeled break Statement


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The continue Statement

The continue statement skips the current iterationofa for, while , or do-while loop.

Theunlabeled form skips to the end of the innermostloop's bodyand evaluates the boolean expression thatcontrols the loop

A labeled continuestatementskips the current

iterationof an outer loopmarked with the givenlabel.

Ex: unlabeled continue Statement


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Ex: unlabeled continue Statement

Ex: labeled


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Ex: labeled

continue

Statement


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Assignment

Makea simple calculator to:

addition,

substraction,

multiplication, division

Use Class Scanner


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NOTES



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Escape Sequence Character

A character preceded by a backslash (\) is an escapesequence and has special meaning to the compiler.The following table shows the Java escape sequences:


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Ex: Escape Sequence Character


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Method printf()

The printf( ) method automatically usesFormatter to create a formatted string.

String format

args


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Method printf() Result

Another Ex: printf()


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Another Ex: printf()

Printf() to command line summary


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Printf() to command line summary

Source: http://www.java2s.com/Tutorial/Java/0120__Development/printftocommandlinesummary.htm

Integer Literals
http://www.java2s.com/Tutorial/Java/0120__Development/printftocommandlinesummary.htmhttp://www.java2s.com/Tutorial/Java/0120__Development/printftocommandlinesummary.htm


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Integer Literals


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Floating-Point Literals

THANKS


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THANKSContact: [email protected]

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