chapter1 introduction to java overview of the java what is the java technology the java virtual...

Chapter1 Introduction to Java

Overview of the Java What Is the Java Technology The Java Virtual Machine A First Application in Java A First Applet in Java A Basic Java Application Using OO Java Terminology and Technology Products

CCE JMU China ZhangJM 2008-09

Reference

Thinking in Java （中、英版） The Java Tutorial Sun Microsystems Java™ Programming Language （中、英版） ( 作者： Ken Arnold 、 James Gosling 、 David

Holmes)

Java 程序设计教程袁兆山等译机械工业出版社


Overview of Java

Past Today Future


• Originally named Oak• Main team members: Bill Joy, Patrick Naughton, Mike Sheridan, James Gosling• Original goal: use with home appliances• In 1994, team realized Oak was perfect for Internet• Announced in May of 1995• First non-beta release in 1996• Java technology is free

The Origin of the Java Programming Language


Java 的渗透力


Java belongs to the world


Joining & Sharing


What Is the Java Technology?

Java technology is: A programming language A development environment An application environment A deployment environment

It is used for developing both Applets and Applications


Java Is A Programming Language


Java Is A Platform


Building a Better Language

• Object-oriented

• Distributed

• Multi-threading

• Security

• APIs (pre-written code)

• Easily portable to multiple platforms

(Write Once, Run Anywhere™)


Primary Goals of the Java Technology

• Provides an easy-to-use language by:

Avoiding many pitfalls of other languages

Being object-oriented

Enabling users to create streamlined and clear code

• Provides an interpreted environment for:

Improved speed of development

Code portability


Primary Goals of the Java Technology

The following features fulfill these goals:

• The JVM

• Garbage collection

• Code security


Java Programs

Applets and Applications

• Application – Runs in the operating system

• Applet – Runs in a browser, does smaller tasks


Basic Components

of a Computer


Applicationsmust use

same languages as

operating and

hardware


Two Ways of Solving the Communication Problem

Compiled

- communicates with only one kind of computer

Interpreted

- communicates with any kind of computer



How Applications Run

HowApplets

Run


A First Application in Java //A First Application in Java public class HelloWorld{ public static void main(String[] args){ System.out.println("Hello

World!"); } }


Run the Application HelloWorld


A first Applet in Java // A first Applet in Java import javax.swing.JApplet; // 导入 Java API 的 JApplet 类 import java.awt.Graphics; // 导入 Java API 的 JGraphics 类 public class HelloWorldApplet extends JApplet { public void paint( Graphics g ) { g.drawString( "Hello World!", 25, 25 ); } }创建 HTML 文件，以将 HelloWorldApplet.java 编译所得

HelloWorldApplet.class 载入浏览器运行。 HelloWorldApplet.html 文件为：

<html> <applet code="HelloWorldApplet.class" width=300 height=30> </applet> </html>


Run the applet HelloWorldApplet



The Java

TechnologyProducts

and Terminology

各章内容概述


chapter1 introduction to java overview of the java what is the java technology the java virtual...

Documents

javacce jmu china zhangjm

anywherecce jmu china

computercce jmu china

sharingcce jmu china

worldcce jmu china zhangjm

platformcce jmu china

hardware cce jmu china

java overview