1 Part I : Chapter 01 Introduction to Java Programming.

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Part I : Chapter 01

Introduction to Java Programming

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Objectives

• To learn about Java and its history.

• To create, compile, and run Java programs.

• To understand the Java runtime environment.

• To write a simple Java application.

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History of Java

• Green Project• Developed by a team led by James

Gosling at Sun Microsystems.• 1991: Oak (use in embedded consumer electronic

application)

• 1995: Java (redesigned for developing Internet applications)

James Gosling and Dukehttp://java.sun.com/people/jag/

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History of Java

• This is a snapshot taken at a barbecue that James Gosling threw for some of the folks associated with the Green Team. From left to right they are: Al Frazier, Joe Palrang, Mike Sheridan, Ed Frank, Don Jackson, Faye Baxter, Patrick Naughton, Chris Warth, James Gosling, Bob Weisblatt, David Lavallee, and Jon Payne. Missing in action: Cindy Long, Chuck Clanton, Sheueling Chang, and Craig Forrest.

• (http://java.sun.com/features/1998/05/birthday.html)

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Java Version HistoryVersion Code-Name Release Date

JDK 1.1.4 Sparkler Sept 12, 1997

115JDK . . Pumpkin Dec 3, 1997

JDK 1.1.6 Abigail April 24, 1998

JDK 1.1.7 Brutus Sept 28, 1998

1 18 Chelsea April 8, 1999

J2SE 1.2 Playground Dec 4, 1998

2 121J SE . . (none) 30 199March ,9

J2SE 1.2.2 Cricket July 8, 1999

2 13J SE . Kestrel May 8 , 2 0 0 0

J2SE 1.3.1 Ladybird May 17, 2001

J2SE 1.4.0 Merlin Feb 13, 2002

2 141J SE . . Hopper Sept 16, 2002

J2SE 1.4.2 Mantis June 26, 2003

2 50 150J SE . ( . .)

Tiger Sept 29, 2004

Java SE 6.0 (1.6.0) Mustang December 11, 2006

Java SE 6 Update 14 - May 28, 2009

70 17Java SE . ( . .0)

Dolphin Plan to release in 2010

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Characteristics of Java

• Java is simple.

• Java is Object-Oriented

• Java is Case-sensitive

• Java is Interpreted (Write-Once, Run-Anywhere)

• Java is Robust

• Java is Multithreaded

• Java can be manipulated in two ways: Application and Applet

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Platform of Java Technologies

• Java, Micro Edition

(JMETM technology)

• Java, Standard Edition

(JSETM technology)

• Java, Enterprise Edition

(JEETM technology)

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Platform of Java Technologies

http://java.sun.com/java2/whatis/index.html

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Architecture of Java

Java Programming Language

Java class file

Java Virtual Machine (Java VM)

Java API

Computer System

Java platform

API = Application Programming Interface

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Typical Java Development Environment

Javasource code

Java compiler(javac)

HTML page

Java Interpreter(java)

Appletvieweror

Browser

Application

Applet

.java .class

.html

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Typical Java Development Environment

Disk

Primary Memory

JVM

Editor

Compiler

Class Loader

Bytecode Verifier

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Style of Java Programming

• Java application– Run in text mode– Run in GUI mode

• Java applet<html>

<applet code=“myApplet.class” width=…

height=…>

</applet>

</html>

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Anatomy of the Application Program

• Comments• Reserved Words• Modifiers• Statements• Blocks• Classes• Methods• The main method

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Java Keywords

• abstract boolean break byte case• catch char class const continue• default do double else extend• false final finally float for• goto if implementation import instanceof• int interface long native new• null package private protected public• return short static super switch• synchronized this throw thows• transient true try voidvolatile• while

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The First Java Application Example

// A first program in Java

public class Welcome

{

public static void main ( String args[] ) {

System.out.println(“Welcome to Java Programming”);

}

}

Begin class definition

Declaration of main methodArguments of main method

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• System.out is a standard output object to display text in text mode

• println is a method of System.out• To call a method, use . between a class /

object’s name and the method– System.out.println(“…”);– car.getLevel();

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• Save as a name of Welcome.java• compile Welcome.java

– javac Welcome.java– See the output

• run– java Welcome– See the output

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Java Application Example II

// Printing multiple lines in a dialog box

import javax.swing.JOptionPane;

public class Welcome2 {public static void main (String args[] ) {

JOptionPane.showMessageDialog ( null, “Welcome\nto\nJava\

nProgramming!”);

System.exit(0); // terminate the program}

}

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• import javax.swing.JOptionPane; to call a class named JOptionPane into the class.

• JOptionPane.showMessageDialog ( null, “Welcome\nto\nJava\nProgramming!”);

call a method named showMessageDialog of JOptionPane class.

• System.exit(0); is applied as the last command of the class to return resource to the system.

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• Save the file as Welcome2.java• compile Welcome2.java

– javac Welcome2.java

– See the output• run

– java Welcome2– See the output

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The First Applet

// The first applet in Java

import javax.swing.JApplet;import java.awt.Graphics;

public class WelcomeApplet extends JApplet {public void paint ( Graphics g ) {

g.drawString(“Welcome to Java Programming”, 25, 25);}

}

inheritance

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The First Applet

• Save the file as WelcomeApplet.java• compile WelcomeApplet.java

– javac WelcomeApplet.java– See the result

• run– Create a html file to call the applet

<html><applet code=“WelcomeApplet.class” width=300 height=30></applet></html>

– Save the .html file. Name the file in any name such as welcome.html

– run by typing appletviewer welcome.html– Or call the .html in any browser program.

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End of Chapter01

Introduction to Java

1 Part I : Chapter 01 Introduction to Java Programming.

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