Lectre 1- Java Intro

8/3/2019 Lectre 1- Java Intro

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Java Programming

Java Basics


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Contents

Background Java Virtual Machine

Application & Applet

Class & Object

3 Principles of Object Oriented Programming

Start up Java

Variables & Assign

String & Character

Arithmetic Operator & Expression

Comment Array

Keywords


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Background / History

Sun Microsystems Inc.

James Gosling

1990, Green Project

1991, Develop the Language for Household Products => To

General Developing Language

Java

James Gosling, Arthur Van Hoff, Andy Bechtolsheim

Coffee Materials in Indonesia

Write once, Run everywhere

Spread Rapidly through WWW and Internet


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Byte Code and Java Virtual Machine

Existing Development Environment

Source

Code

Compiler(Pentium)

Compiler(PowerPC)

Compiler(SPARC)

Binary

File

Pentium

PowerPC

SPARC

Binary

File

Binary

File%cc Hello.c o Hello

% Hello

Binary CodeRun


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Byte Code and Java Virtual Machine

Java Development Environment

Java Compiler

(Pentium)

Java Compiler

(PowerPC)

Java Compiler

(SPARC)

Java

Interpreter

Pentium

PowerPC

SPARC

Java

Interpreter

Java

Interpreter

Java

Code

Java

ByteCode

(Independent on

Platform)

%javac Hello.java

Hello.class created

% java Hello

Byte CodeRun JVM


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Java Program

Java Application Program

Application

Program written in general programming

language

Applet

Program running in Web Browser Environment

Can be viewed by appletviewer or Web browser

with JVM


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Class and Object

Object

Memory Space to Define State and Operation

Instance of Class

Class Template of Creating Object


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3 Principles of Object Oriented Programming

Encapsulation

Control Access the data and method in program code

Inheritance

Inherit the data and methods of parent class

Polymorphism

Shape

Ellipse Rectangle Triangle

getArea()

getArea() getArea()getArea()

Shape Obj = new Ellipse();

Obj.getArea();

Which Area?


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Java Class Library

java.applet : Applet related java.awt : Abstract Window Toolkit

java.awt.event : Event process from awt component

java.awt.image : Image processing

java.beans : JavaBeans Component java.io : File or Network I/O Support

java.lang : Java Language Support

java.net : Network related functions

java.util : Utility function


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Java 2 SDK

Java 2 Software Development Kit (Java 2 SDK)

Java Application or Applet Development and

Running Environment

Java 2 Runtime Environment (JRE) Java Running Environment

Java 2 Standard Edition

Java 2 Micro Edition Java 2 Enterprise Edition


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Java Program Structure

In the Java programming language: A program is made up of one or more classes A class contains one or more methods A method contains program statements

These terms will be explored in detail throughout the course A Java application always contains a method calledmain


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public class MyProgram{

}

// comments about the class

class header

class body

Comments can be placed almost anywhere


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public class MyProgram{

}

// comments about the class

public static void main (String[] args){

}

// comments about the method

method headermethod body


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Start Java Application

Hello.java

class Hello {

public static void main(String args[]) {

System.out.println(Hello World);

}

% javac Hello.java

% java Hello

Compile

Run

hello.c

void main() {

printf(Hello World\n);

}

% cc hello.c o hello

% hello

Hello WorldResult

Java C

Class Name

Main method

Main Function


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Variable and Assign

Variable

Type

char 16bits Unicode character data

boolean Boolean Variable

byte 8 bits signed integer short 16 bits signed integer

int 32 bits signed integer

long 64 bits signed integer

float 32 bits signed floating point number

double 64 bits signed floating point number


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Variable and Assign

int num = 100;

long m = 21234234L

double type : .5 0.8 9e-2 -9.3e-5float type : 1.5e-3f;

Variable Declaration

type varName;

Value assign

varName = value;

float x, y, x;


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String and Character

String : sequence of character

String s = Enter an integer value: ;

Char c = A;

Concatenation Operator +

String s = Lincoln said: + \ Four score and seven years ago\ ;

Result :

Lincoln said: Four score and seven years ago

Unicode


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Arithmetic Operator

Operators

+ - * / %

+= -= *= /= %=

++ --

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2 Why isnt it 2.5 ?5 % 2 14 / 2 24 % 2 0

count * num + 88 / val19 % count

j += 6; j = j + 6;


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Comment

Single Line Comment

int i = 10 ; //i is counter

Multiple Line Comment

/*

Some comments*/

Documentation Comment

/**

Documentation Comment

*/

Using javadoc Tool,

make document


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Arrays ( One Dimensional)

type VarName[]

Definition of One Dimensional Array

int ia[];

varName = new type[size]

Assign Range to One Dimensional Array

ia = new int[10];

type varName[] = new type[size]

Declaration of One Dimensional Array with Range

int ia[] = new int[10];


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Arrays ( One Dimensional)

varName.length

Number of elements in Array

Type varName[] = {e0, , en};

Initialization of One Dimensional Array

int j[] = {0, 1, 2, 3, 4, 5};

int k[];

K = j;

Example 1.15


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Arrays ( Multi-Dimensional)

type VarName[][];

Definition of Two Dimensional Array

float fa[][];

varName = new type[size1][size2];

Assign Range to Two Dimensional Array

fa = new float[2][3];

type varName[][] = new type[size1][size2];

Declaration of Two Dimensional Array with Range

float fa[] = new float[2][3];


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Arrays ( Two Dimensional)

varName.length

Number of elements in Multi-Dimensional Array

Type varName[][] = {{e00,

, e0n}, {e10,

,e1y}, {e20,

, e2z}};

Initialization of Multi-Dimensional Array

Example 1.16

varName[index].length

Number of elements in Each elements of Multi-Dimensional Array

Number of Raw


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Java Keywords

47 Java Keywordsabstract double int super

boolean else interface switch

break extends long synchronized

byte final native this

case finally new throwcatch float package throws

char for private transient*

class goto* protected try

const* if public void

continue implements return volatile

default import short while

do instanceof static

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Lectre 1- Java Intro