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Lecture 1

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Benefits of This LanguageJAVA Programs

The Java Environment

Installing JAVA Compiling and Running JAVA Program

Object-Oriented Programming in Java

JAVA Program

JAVA Library

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ExampleJAVA and Unicode

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Machine independent

Object oriented

support national character sets

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Applets : Programs that are to be embedded in a web

page

Java applications:

console applications

graphical user interface (GUI)

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Download SDK and install it Set the PATH and add to it c:\jdk1.5\bin

Add to CLASSPATH c:\jdk1.5\lib ,

c:\jdk1.5\jre\lib

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Compile:Javac [-classpath .] name.java

Run

Java [-classpath .] name of class

You put your projectin the current

directory

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Anything can be thought of as an object. A class consists of:

Attributes

Objects

Encapsulation

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A Java program always consists of one ormore classes.

You typically put the program code for eachclass in a separate file, and you must giveeach file the same name as that of the classthat is defined within it.

A Java source file must also have the

extension .java. Each line command must end with ;

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The classes are grouped together into relatedsets that are called packages, and eachpackage is stored in a separate directory.

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ExamplesPackage Name Description

java.lang These classes support the basic language features and the handling of arrays and strings.Classes in this package are always available directly in your programs by default because thispackage is always automatically loaded with your program.

java.io Classes for data input and output operations.

java.util This package contains utility classes of various kinds, including classes for managing datawithin collections or groups of data items.

javax.swing These classes provide easy-to-use and flexible components for building graphical userinterfaces (GUIs). The components in this package are referred to as Swing components.

java.awt Classes in this package provide the original GUI components (JDK1.1) as well as some basicsupport necessary for Swing components.

java.awt.geom These classes define 2-dimensional geometric shapes.

java.awt.event The classes in this package are used in the implementation of windowed application tohandle events in your program. Events are things like moving the mouse, pressing the leftmouse button, or clicking on a menu item.

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To add a package to your project:Import packagename ;

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Public class test{Public static void main(string args[])

{

System.Out.println(my first test);}

}

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Characters are represented in 16 bit ratherthan 8 bit of ASCCI