交通大學資訊工程學系 Programming in Java Getting Started 蔡文能交通大學資訊工程學系 [email protected] tsaiwn/java//java

交通大學資訊工程學系

Programming in Java

Getting Started

蔡文能交通大學資訊工程學系[email protected]

http://www.csie.nctu.edu.tw/~tsaiwn/java/

交通大學資訊工程學系蔡文能第 2頁

Java Getting Started

OutlineJava History …

Java vs. C++

Compilation and Interpretation

Java Platform

Java Applications

Java Applets

Language Basics

Inside the Applets

Applications using GUI

More about Applets



Java History

December, 1990. Patrick Naughton started the Green Project in Sun. He recruited James Gosling and Mike Sheridan to help start the project.

James Gosling is of emacs fame. (Not James Bond :-)

April 1991 The Green Project (Naughton, Gosling and Sheridan) settled on smart

consumer electronics as the delivery platform

June 1991 (Gosling想為該語言命名時看到了窗外的一棵橡樹 ) Gosling started working on the "Oak" compiler (in C), renamed

“Java” later. Naughton, Gosling and Sheridan wrote the runtime-interpreter,

also in C Language. August 1991 Green team demonstrates basic user interface ideas and graphics

system to Sun co-founders Scott McNealy and Bill Joy.



Interactive TV

Summer 1992 Massive amounts of hacking on Oak, and related components.

October 1992 Wayne Rosing joined from Sun Labs and assumed management of

the team.

March 1993 The team, incorporated as First Person, focused on interactive

television after learning about Time Warner's RFP for its interactive cable TV.

April 1993 NCSA Mosaic 1.0, the first graphical browser for the Internet, was

released.

June 1993 Time Warner went with SGI for its interactive cable TV trial, despite

acknowledged superiority of Sun technology.



Change to Internet

Summer 1993 Naughton flew 300,000 miles selling Oak to anyone involved in

consumer electronics and interactive television. The rate at which people were gaining access to the Internet reaches

breakneck speed.

April 1994 Sun Interactive created, half of FirstPerson employees leave to join it.

June 1994 "Liveoak" project started. Designed by Bill Joy to use Oak for a big

small operating system project.

July 1994 Naughton simply retargeted Oak at the Internet after writing a

throwaway implementation of a Web browser in a long weekend hack.



Start Licensing

September 1994 Jonathon Payne and Naughton start writing "WebRunner," a

Mosaic-like browser later renamed "HotJava“. HotJava prototype is first demonstrated to Sun executives.

May 1995 Sun formally announces Java and HotJava at SunWorld '95. Netscape announces its intention to license Java for use in

Netscape browser.

September 1995 Sun-sponsored Java development conference held in New York

City. Sunsoft announces suite of business-oriented development

products incorporating Java.



Quick GrowthOctober 1995 Oracle announces its Web System suite of WWW software which includes

a Java-compatible browser. At the Internet World Conference in Boston, many companies announce

plans to license Java.Lotus Development Corp., Intuit Inc., Borland International Inc., Macromedia Inc., Spyglass Inc.

December 1995 Sun and Netscape announced Javascript, a scripting language based on

Java. Sun, Netscape and Silicon Graphics announced new software alliance to

develop Internet interactivity tools. Borland, Mitsubishi Electronics, Sybase and Symatec announced plans to

license Java. IBM and Adobe announce licensing agreement with Sun for use of Java. Microsoft announces plans to license Java during announcement of suite of

new Internet products, including Visual Basic Script.



Technology Timeline

See http://java.sun.com/features/2000/06/time-line.html

A Brief History of the Green Project by James Gosling http://java.sun.com/people/jag/green/index.html

The Story of the Java Platform on the java.sun.com Web site http://java.sun.com//nav/whatis/storyofjava.html

Java: The Inside Story by Michael O'Connell in SunWorld Online http://www.sun.com/sunworldonline/swol-07-1995/swol-07-java.html

The Java Saga by David Bank in Wired http://www.wired.com/wired/archive/3.12/java.saga.html

What is Java technology - 1996 http://java.sun.com/java2/whatis/1996/

Java technology: An Early History - 1998 http://java.sun.com/features/1998/05/birthday.html



Sun announced Java on 1995/05/23











JSP



JDK – Java development Kit

1995 May JDK 1.0

1996 add IDL(Interface Definition Language), RMI (Remote Method Invocation), Java Beans, JDBC (Java DataBase Connectivity)

1997 JDK 1.1, add Servlet

1998 November Java 2 (JDK 1.2)

1999 Oct JDK 1.3; 2001 JDK 1.3.1

2002 JDK 1.4

2004 JDK 1.5 (JDK 5.0)

2006 JDK 6.0 (JDK 1.6)



java.applet, java.awt, java.io, java.lang, java.net, java.util

java.math, java.rmi, java.security, java.sql, java.text, java.beans

javax.accessibility, javax.swing, org.omg

javax.naming, javax.sound, javax.transaction

java.nio, javax.imageio,javax.net, javax.print,javax.security, org.w3c

javax.activity,javax.management

JDK 1.08 packages212 classes






New Events

Inner class

Object Serialization

Jar Files

International

Reflection

JDBC

RMI

JFC/Swing

Drag and Drop

Java2D

CORBA

JNDI

Java Sound

Timer

Regular ExpLoggingAssertionsNIO



Removed Features from C++

pointers --- where the virus is from

operator overloading --- too obscure

multiple inheritance --- too problematic

preprocessing --- unreadable

unions, structs, templates --- unnecessary

automatic coercions --- weak on typing

destructors --- when to do?

goto --- we all know why.

Java == C++--++

Java

C++

C



Added FeaturesTypes: (8 primitive types and their class wrappers) boolean (1bit), byte (8 bit signed), char (16 bit, Unicode), short (16bit), int (32bit), long (64bit), float, double, String, Array (as object)

Multi-level break 從此真的可以不必用 goto (拿掉了 )Interfaces 不可多重繼承 ; 但可 implement多個介面Packages 把相關的 class 集合在同一個子目錄Automatic garbage collection 不再有 memory leakingMultithread and synchronizationException handling ( 做得比 C++ 好 ) (C只有 signal和longjmp)Runtime type checking

Java == C++--++



Compilation and Interpretation

Compilation Source code Bytecode

MyProgram.java MyProgram.class (注意大小寫 )

Interpretation Bytecode

the machine code instructions for the Java Virtual Machine.

the platform-independent codes interpreted by the Java interpreter.



Write Once, Run Everywhere

Other sayings, Write once, test everywhere. Write once, tune everywhere.



Advantages of Java

Platform independent, portable and interoperable

Mobile over distributed systems

Simple, Object-Oriented

Robust and secure

Reasonably good performance

Interpreted (bytecode)

Multithreaded

. . .

Java

C++

C



How Will Java Change My Life?

Java will help you do the following: Get started quickly Write less code Write better code Develop programs faster Avoid platform dependencies with 100% Pure Java Write once, Run anywhere Distribute software more easily

Well, but better to Use OOA and OOD to help code Follow Design Patterns. Notice the performance problem.

E.g., gaming.



Java Platform

Java Virtual Machine (JVM)

Java API where you need to learn more.

API :Application Programming Interface



Java Editions

J2EE, J2SE, J2ME



Java API

The core API gives you the following features: The Essentials Applets Networking Internationalization GUI (Graphical User Interface) Security Software components Object serialization ……

API :Application Programming Interface



Of course you can visit home of java: http://java.sun.com/






要看

!




Types of Java Programs

Applications A standalone program just like a console applications for C/C++.

Applets A plug-in program inside a web page. (runs in a web browser)

Servlets A plug-in program inside a web page but running on server side.

JSP (Java Server Page) An HTML-like text program with Java code. Similar to ASP and PHP.



Java Applications (standalone programs)

A Java Application is a standalone program.

The source code of HelloWorldApp.java:

/** * The HelloWorldApp class implements an application that * simply displays "Hello World!" to the standard output. */class HelloWorldApp { public static void main(String[] args) { System.out.println("Hello World!"); //Display the string. } }

public class name should be same as the name of Java Source File name



The main method

The main Method Every Java application must contain a main method whose signature looks like this:

public static void main(String[] args)

public indicates that the main method can be called by any object. static indicates that the main method is a class method. void indicates that the main method does not return any value.

public static void main(String[] args) { ... }

Arguments to the main Method args indicates the strings behind the class name in

the command line. The runtime system passes information to your application through

this String array. For example:

java showimage image.gif



Compiling and Run the Application

Compiling the source file Command line operation

> javac HelloWorldApp.java This operation generates HelloWorld.class Javac is the Java Compiler

Run the Application Command line operation

> java HelloWorldApp The argument to the Java interpreter is the name of the class to run,

not the name of a file. java is the Java Interpreter, also known as JVM(Java Virtual Machine)



The Annotation

Comments in Java Code /* text */

/** documentation */ The JDK javadoc tool uses doc comments when preparing automatically generated documentation.

Most JDK manuals are generated by the javadoc tool.

// text



Javadoc

See more in http://java.sun.com/j2se/javadoc/writingdoccomments/index.html

/** * Registers the text to display in a tool tip. The text * displays when the cursor lingers over the component. * * @param text The string to display. If the text is null, * the tool tip is turned off for this component. */ public void setToolTipText(String text) {

More tags* @author (classes and interfaces only, required)* @version (classes and interfaces only, required) (see footnote 1)* * @param (methods and constructors only)* @return (methods only)* @exception (@throws is a synonym added in Javadoc 1.2)* @see * @since * @serial (or @serialField or @serialData)* @deprecated (see How and When To Deprecate APIs)



An Example of Applet

A Java Applet runs in web browser.

The source code of HelloWorld.java:

import java.applet.Applet;import java.awt.Graphics;

public class HelloWorld extends Applet { public void paint(Graphics g) { g.drawString("Hello world!", 50, 25); } }



Run the Applet

HTML File that Includes the Applet

<HTML><HEAD><TITLE>A Simple Program</TITLE></HEAD><BODY> Here is the output of my program:<APPLET CODE="HelloWorld.class" WIDTH=150 HEIGHT=25></APPLET></BODY></HTML>

• Run the Applet– Compile the HelloWorld.java onto HelloWorld.class

> javac HelloWorld.java– Command line operation to run

> appletviewer Hello.html– Use IE to read the HTML file.



The Anatomy of a Java Applet (1/4)Importing Classes and Packages

import java.applet.Applet; // import java.applet.*; import java.awt.Graphics; // import java.awt.*;public class HelloWorld extends Applet { public void paint(Graphics g) { g.drawString("Hello world!", 50, 25); } }

=====================================================

public class HelloWorld extends java.applet.Applet { public void paint(java.awt.Graphics g) { g.drawString("Hello world!", 50, 25); } }

Java.lang.* 是唯一不必 import 的package



The Anatomy of a Java Applet (2/4)

Defining an Applet Subclass import java.applet.Applet;

import java.awt.Graphics; public class HelloWorld extends Applet { public void paint(Graphics g) { g.drawString("Hello world!", 50, 25); } }

Applets inherit a great deal of functionality from the Applet class.

The most important is the ability to respond to browser requests.

拿 Java.applet.Applet.class 來擴充 !



The Anatomy of a Java Applet (3/4)Implementing Applet Methods

import java.applet.Applet; import java.awt.Graphics; public class HelloWorld extends Applet { public void paint(Graphics g) { g.drawString("Hello world!", 50, 25); } }

The Graphics object represents the applet's onscreen drawing context. This applet draws the string "Hello world!" starting at location (50,25). The applet's coordinate system starts at (0,0), which is at the upper left

corner of the applet's display area.

paint(Graphics) 這函數最重要 !



The Anatomy of a Java Applet (4/4)

Running an Applet : embed it into an HTML page <HTML>

<HEAD><TITLE>A Simple Program</TITLE></HEAD> <BODY> Here is the output of my program: <APPLET CODE="HelloWorld.class" WIDTH=150 HEIGHT=25> </APPLET> </BODY> </HTML>

The <APPLET> tag tells that the browser should load HelloWorld.class.

When the browser finds the class file, it loads it over the network, if necessary, onto the computer the browser is running on.

The WIDTH and HEIGHT attributes specify the size in pixels of the applet's display area.



MyFirstCoffee.java (Applet sample) p1/2 import java.applet.Applet; import java.awt.*; // Graphics, Font, Color, ... public class MyFirstCoffee extends Applet { ///////////// 注意檔名要與 Class 名相同 String s; // global 變數以便後續 function 也可用 public void init ( ) { //通常寫只會做一次的工作 s= getParameter("MSG"); // 抓 <applet> 裡的參數 MSG放 s } public void paint (Graphics g) { if(s == null ) s= "Ha Ha Ha !\nHee Heeee!"; // 在 appletviewer抓不到ㄟ , 阿只好 ...(bug? 可能 HTML沒寫好 )

g.clearRect(0, 0, getSize().width, getSize().height); g.setColor(Color.blue); // 所有顏色常數是小寫 ! 怪哉 ? 因為可以改 g.setFont( new Font("Courier", Font.BOLD, 32) ); setBackground(Color.green); //這是 Applet的method g.drawString("Hey You!", 44, 80 );



MyFirstCoffee.java (p2/2)

g.setColor(Color.red); // 所有顏色常數是小寫 ! 變數 ! g.drawRect(55, 160-32, 20*s.length() , 36); // red g.setColor(Color.yellow); g.fillRect(57, 160-32+2, 20*s.length()-4 , 36-4); /// g.setFont( new Font("Courier", Font.PLAIN, 24) ); g.drawString("s.length()="+s.length(), 60, 220); g.setFont( new Font("Courier", Font.BOLD, 32) ); g.setColor(Color.magenta); // magenta g.drawString(s, 60, 160 ); g.setFont( new Font("標楷體 ", Font.BOLD, 32) ); g.setColor(Color.orange); // orange g.drawString(s, 60, 280 ); } }



HTML to run MyFirstCoffee

<HTML>

<BODY>

<HR width=66%>

<APPLET code="MyFirstCoffee.class" width=580 height=320>

<PARAM name="MSG" value="I am Big Head Lee 李大頭 !">

<param name="P2" value = "No use this time">

</applet>



<HR width=88%>

</body>

</html>

注意 : 該 .class檔在 Server 上要與此HTML 檔放一起 ; 否則要在 <applet …>裡

指定 codebase



Applet MyFirstCoffee is running

要如何把 HTML 檔 run 起來 ? 當然可放到 WEB 網站 .

若在 Windows XP, 則直接執行該 HTML 檔即可 !



唐詩宋詞

Take a Break! 蝶戀花柳永 .

獨倚危樓風細細。

望極春愁，黯黯生天際。

草色山光殘照裏，

無人會得憑闌意，

也擬疏狂圖一醉。

對酒當歌，強樂還無味。

衣帶漸寬終不悔，為伊銷得人憔悴。

為愛痴狂劉若英

我從春天走來你在秋天說要分開說好不為你憂傷但心情怎會無恙

為何總是這樣在我心中深藏著你想要問你想不想陪我到地老天荒

如果愛情這樣憂傷為何不讓我分享日夜都問你也不回答怎麼你會變這樣

想要問問你敢不敢像你說過的那樣的愛我 ﹝ 想要問問你敢不敢 ﹞

像我這樣為愛癡狂到底你會怎麼想◎為愛痴狂收錄在劉若英個人專輯『少女小漁劉若英的美麗與哀愁』中。

浪淘沙李煜

簾外雨潺潺，春意闌珊。

羅衾不耐五更寒。

夢裡不知身是客，一餉貪歡。

獨自莫憑闌，無限江山，別時容易見時難。

流水落花春去也，天上人間。



Java Language BasicsVariables and Data typesOperators Arithmetic Operators Relational and Conditional Operators Shift and Logical Operators Assignment Operators Other Operators

Expressions, Statements, and Blocks Control Flow Statements The while and do-while Statements The for Statement The if/else Statements The switch Statement Exception Handling Statements Branching Statements

任何高階電腦語言都該有的指述 :

/* 註解 */ //也是註解

宣告 / 定義變數和常數

運算符號與運算式和 Assignment =

•算術 , 關係運算 , 邏輯

{ compound statements; }

控制指述 (control statements)

Sequence

Alternative (selection)

•if-else, switch

Loop: for, while, do while

Function/procedure call



Variables and Types in Java

Primitive (simple) types boolean (1 bit) byte (8 bit, signed) char (16 bit, UNICODE) short (16 bit, signed) int (32bit, signed) long (64 bit, signed) float (32 bit, IEEE 754) double (64 bit, IEEE 754)

Reference types (use pointers to access) array types class types interface types



Language Fundamentals

Assignments Copy values for primitive types Assign only references for objects

Parameter passing Call by values

Copy values for primitive types

Call by referencesPass references for reference types.

Objects access accessing Objects through references accessing null reference throws NullPointerException



Calss wrapper for primitive data typesInteger: (in java.lang.Integer)

class Integer { int i;

Integer (int value) { i = value; }; ...... String toString(); long longValue() {return (long)i;} ......}...... Integer a = new Integer(3849);Integer b = a;Integer c = b;

int i

a b c

What are the internal data structures?



Calss wrapper for primitive data types(cont.)

Boolean for boolean

Byte for byte

Character for char

Short for short

Integer for int

Long for long

Float for float

Double for double

Primitive data typesClass

Wrappers

八大原始類別



Arrays (different from array in C++)Arrays Arrays are objects Arrays are dynamic Arrays are passed by reference Arrays are bounds checked (starts with 0 and ends with length - 1)

int[] rgb = new int[3];rgb[0] = 255; rgb[1] = 100; rgb[2] = 150; int avg = sum(rgb) / rgb.length ;int err = rgb[3]; //oops! Error!...int sum(int[] arr){int result = 0;for (int i=arr.length; --i>=0;) result += arr[i];return result;

}

What are the internal operations?



Operators

Operator types: Unary operators : require one operand, for example, ++. Binary operators : require two operands, for example, =. Ternary operators require three operands. The only one in Java is ?:

Which is a short-hand if-else statement.

Prefix : operator op Postfix : op operator Infix : op1 operator op2 expr ? op1 : op2



Arithmetic Operators

Arithmetic Operators+ op1 + op2 Adds op1 and op2

- op1 - op2 Subtracts op2 from op1

* op1 * op2 Multiplies op1 by op2

/ op1 / op2 Divides op1 by op2

% op1 % op2 Computes the remainder of dividing op1 by op2

++ op++ Increments op by 1; evaluates to value before incrementing

++ ++op Increments op by 1; evaluates to value after incrementing

-- op-- Decrements op by 1; evaluates to value before decrementing

-- --op Decrements op by 1; evaluates to value after decrementing



Relational Operators Operator Use Return true if

> op1 > op2 op1 is greater than op2

>= op1 >= op2 op1 is greater than or equal to op2

< op1 < op2 op1 is less than op2

<= op1 <= op2 op1 is less than or equal to op2

== op1 == op2 op1 and op2 are equal

!= op1 != op2 op1 and op2 are not equal



Conditional Operators

Operator Use Return true if

&& op1 && op2 op1 and op2 are both true,conditionally evaluates op2

|| op1 || op2 either op1 or op2 is true,conditionally evaluates op2

! ! op op is false

& op1 & op2 op1 and op2 are both true, alwaysevaluates op1 and op2

| op1 | op2 either op1 or op2 is true, alwaysevaluates op1 and op2



Bitwise OperatorsOperator Use Operation

>> op1 >> op2 shift bits of op1 right bydistance op2

<< op1 << op2 shift bits of op1 left bydistance op2

>>> op1 >>> op2 shift bits of op1 right bydistance op2 (unsigned)

& op1 & op2 bitwise and

| op1 | op2 bitwise or

^ op1 ^ op2 bitwise oxr

~ ~ op bitwise complement



Assignment Operators

Operator Use Equivalent to+= op1 += op2 op1 = op1 + op2-= op1 -= op2 op1 = op1 - op2*= op1 *= op2 op1 = op1 * op2/= op1 /= op2 op1 = op1 / op2

%= op1 %= op2 op1 = op1 % op2&= op1 &= op2 op1 = op1 & op2|= op1 |= op2 op1 = op1 | op2^= op1 ^= op2 op1 = op1 ^ op2

<<= op1 <<= op2 op1 = op1 << op2>>= op1 >>= op2 op1 = op1 >> op2

>>>= op1 >>>= op2 op1 = op1 >>> op2



ExpressionsDefinition: An expression is a series of variables, operators, and method calls that evaluates to a single value. The data type of the result of an expression depends on the

elements used in the expression. A method call expression evaluates to the return value of the

method.



Operator Precedencepostfix operators [] . (params) expr++ expr--unary operators ++expr --expr +expr -expr ~ !creation or cast new (type)exprmultiplicative * / %additive + -shift << >> >>>relational < > <= >= instanceofequality == !=bitwise AND &bitwise exclusive OR ^bitwise inclusive OR |logical AND &&logical OR ||conditional ? :assignment = += -= *= /= %= &= ^= |=

<<= >>= >>>=



Control Flow StatementsControl flow statements in Java

Statement Keyword Decision making if-else, switch-case Loop for, while, do-while Exception try-catch-finally, throw Branching break, continue, label: , return

Block A statement block is a series of statements within '{' and '}'.

if (na < nb) {

temp = na;

na = nb; nb = temp;

}



if-else Statements

The if-else Statement The simple form of if can be written like this

if ( booleanExpression )

statement

The else block is executed if the if part is false.

…… if (response == OK) {

…… // code to perform OK action

} else {

…… // code to perform Cancel action

}



Another form of the else statement

if (testscore >= 90) {

grade = 'A';

} else if (testscore >= 80) {

grade = 'B';


grade = 'C';


grade = 'D';

} else {

grade = 'F';

}



switch StatementsThe switch Statement

int month;

. . .

switch (month) {

case 1: System.out.println("January");

break;

case 2: System.out.println("February");

break;

. . .

case 12: System.out.println("December");

break;

}

break statements cause control to break out of the switch.



default statement at the end of the switch to handle other all cases.. . .

switch (month) {

case 1: System.out.println("January");

break;

. . .

case 12: System.out.println("December");

break;

default:

System.out.println("Hey, that's not a

valid month!");

break;

}



for-Loop Statements

for (initialization; termination; increment)

statements;

int i;

int length = a.length;

for (i = 0; i < length; i++) {

. . .

// do something to the i th element of a

. . .

}



while -Loop Statements

while ( booleanExpression ) statement;

k = 0;

while ( k < 9 ) ++k;

while (in.read() != -1) {

count++;System.out.println("Count = " + count);

}



Example: Counting characters

import java.io.*;public class Count {

public static void countChars(Reader in) throws IOException

{ int count = 0; while (in.read() != -1)

count++; System.out.println("Counted " + count + " chars."); } // ... main method omitted ...}

In case I/O Exception



do-while Loop Statementsdo {

statements

} while (booleanExpression);

Example:int c;

Reader in;

. . .

do {

c = in.read();

. . .

} while (c != -1);



Exception Handling StatementsWhen an error occurs within a Java method, the method can throw an exception to indicate to its caller that an error occurred and the type of error that occurred.

The calling method can use the try, catch, and finally statements to catch and handle the exception.

try {

/* … java statements */

} catch ( /* exception object */ ) { /* … */

} catch ( /* exception object */ ) { /* … */

} finally { /* … * }



Branching StatementsAnother form of the break statement

statementName_Label:

. . . some Java Statements

break statementName_Label;

The continue statement The unlabelled form. if( booleanExpression ) continue; The labeled form. continue statementName_Label;

The return statement Return a value. return; Does not return a value. return a+b;



Multi-Level Branchingpublic int indexOf(String str, int fromIndex) {. . . . . . test: for (int i = offset + ((fromIndex < 0) ? 0 :fromIndex); i <= max ; i++) { int n = str.count; int j = i; int k = str.offset; while (n-- != 0) { if (v1[j++] != v2[k++]) { continue test; // continue; }

if ( ... ) break test; } return i - offset; } return -1; }



for Loop vs. while Loop (same as in C++)

for(i=1 ; i<= 9 ; i++){ /* Loop body */}

i=1;for( ; i<= 9 ; ){ /* Loop body */ i++;}

i=1;while( i<= 9 ){ /* Loop body */ i++;}

These 3 structures have These 3 structures have the same meaningthe same meaning

這三個寫法意義這三個寫法意義完全一樣完全一樣



for Loop vs. while Loop (cont.)

for( ; ; ) ;

;while( ){ ; ;}

== 0

!= 0



while Loop example

拿盤子 , 拿飲料 , 找好位子 ;while(肚子還餓 ){ 吃一盤 ; 喝一杯 ; 喘一口氣 ;}結帳 ; 回家 ;

All you can eat !



while Loop example(cont.)

拿盤子 , 拿飲料 , 找好位子 ;while( 肚子還餓 ){ 吃一盤 ; if( 有急事 || 很飽了 )break; if(不會渴 ) continue; 喝一杯 ; 喘一口氣 ;}結帳 ; 回家 ;

不夠本

All you can eat !



唐詩宋詞

Take a Break! 蝶戀花柳永 .

獨倚危樓風細細。

望極春愁，黯黯生天際。

草色山光殘照裏，

無人會得憑闌意，

也擬疏狂圖一醉。

對酒當歌，強樂還無味。

衣帶漸寬終不悔，為伊銷得人憔悴。

為愛痴狂劉若英

我從春天走來你在秋天說要分開說好不為你憂傷但心情怎會無恙

為何總是這樣在我心中深藏著你想要問你想不想陪我到地老天荒

如果愛情這樣憂傷為何不讓我分享日夜都問你也不回答怎麼你會變這樣

想要問問你敢不敢像你說過的那樣的愛我 ﹝ 想要問問你敢不敢 ﹞

像我這樣為愛癡狂到底你會怎麼想◎為愛痴狂收錄在劉若英個人專輯『少女小漁劉若英的美麗與哀愁』中。

浪淘沙李煜

簾外雨潺潺，春意闌珊。

羅衾不耐五更寒。

夢裡不知身是客，一餉貪歡。

獨自莫憑闌，無限江山，別時容易見時難。

流水落花春去也，天上人間。



Inside the Applet

An Applet is a Panel.

Every applet is implemented by creating a subclass of the Applet class.



A tipical Applet program (p.1/2)import java.applet.Applet;import java.awt.Graphics;

public class Simple extends Applet {StringBuffer buffer;

public void init() {buffer = new StringBuffer();addItem("initializing... ");

} public void start() {

addItem("starting... ");} public void stop() {

addItem("stopping... ");}public void destroy() {

addItem("preparing for unloading...");}

/* ... More on next page... */



A tipical Applet program (p.2/2)

void addItem(String newWord) {System.out.println(newWord);

buffer.append(newWord); repaint();

}

public void paint(Graphics g) {//Draw a Rectangle in the applet's display area.

g.drawRect(0, 0, size().width-1, size().height-1);

//Draw the current string inside the rectangle. g.drawString(buffer.toString(), 5, 15);

}}



The Life Cycle of an AppletLoading the Applet When an applet is loaded, here's what happens:

An instance of the applet class is created.The applet initializes itself.The applet starts running.

Leaving and Returning to the Applet's Page Leaves the page -- go to another page -- the applet stopping itself. Returns to the page, the applet can start itself again. The same sequence occurs when the user iconifies and then reopens the

window that contains the applet.

Reloading the Applet Reload applets -- unloading the applet and then loading it again. Before unloaded, applet stop itself and then to perform a final cleanup.

Applet can release any resources it holds.

Quitting the Browser Applet stop itself and do final cleanup before the browser exits.



Methods for Applet

init initialize the applet when load (or reloaded).

start start the applet's execution when the applet's loaded.

stop stop the applet's execution when the user leaves the page or quits the browser.

destroy perform a final cleanup in preparation for unloading.

public class Simple extends Applet { . . . public void init() { . . . } public void start() { . . . } public void stop() { . . . } public void destroy() { . . . } . . .}



Drawing and Event Handling

paint The basic display method.

update A method you can use along with paint to improve drawing

performance. The default one will clear the screen and then call paint().

So, this may cause blinking.

class Simple extends Applet { . . . public void paint(Graphics g) {

. . . } . . .}



Applets inherit a group of event-handling methods (e.g., addMouseListener(this)) from the Component class.

import java.awt.event.MouseListener;import java.awt.event.MouseEvent;. . .Public class Simlpe extends Applet implements MouseListener {

. . .Public void init(){

addMouseListener(this);. . .

}. . .Public void mouseClicked(MouseEvent event){

addItem(“click!…”);}

. . .}



A Simple Application using GUI

Test the GiGi.java javac GiGi.java java GiGi

GUI : Graphical User Interface



GiGi.java: A Simple Application using GUIimport java.awt.*;import java.awt.event.*;public class GiGi implements ActionListener{ Frame f = new Frame("Window 2001"); Button b1,b2,b3; Panel p; Button n, bq, big; int xSize=300, ySize=200; Dimension dim =

Toolkit.getDefaultToolkit().getScreenSize(); TextArea tx= new TextArea("Hey 我愛 GiGi",

5,20,TextArea.SCROLLBARS_HORIZONTAL_ONLY); public static void main( String s[]) { new GiGi(); }

/* More on next page ... */

(p1./4)



GiGi.java (p2./4) public GiGi() { // Constructor f.setSize(xSize,ySize); f.setLocation(100,100); tx.append("\n=== ==== ==== TextArea tx="); tx.append(" new TextArea(\"Hey 我愛 GiGi\",

5,20,"); tx.append(

" TextArea.SCROLLBARS_HORIZONTAL_ONLY);\n"); tx.append(

"If 如果 GiGi 不漂亮 , 你還會覺得她的歌好聽嗎 ?\n"); b1=new Button("111"); b2=new Button("222"); p = new Panel(); n= new Button("HahaHehehe");

p.add(n); bq=new Button("Quit"); p.add(bq); bq.setBackground(new Color(38,38,38));

bq.setForeground(Color.red); big=new Button("Bigger"); p.add(big); big.setForeground(new Color(255,0,0)); n.setBackground(Color.green);



GiGi.java (p3./4)

n.addActionListener(this); //有事交給此程式中 // 的 actionPerformed()

b1.addActionListener(this); bq.addActionListener(this); big.addActionListener(this); f.add(tx,"Center"); //文字擺中間 f.add(b1,"West"); ; f.add(b2,"East"); f.add(p,"South");

f.show();} /* GiGi – the constructor */



GiGi.java (p4./4) public void actionPerformed(ActionEvent evt){ if(evt.getSource() == n){ n.setBackground(Color.red);

n.setLabel(" 777 "); } /* evt... == n */ if(evt.getSource() == b1) n.setLabel("Eleven"); if(evt.getSource() == bq) System.exit(0); if(evt.getSource() == big){ xSize = (int) (xSize*1.2);

if(xSize>dim.width) xSize= dim.width; ySize = (int) (ySize*1.2);

if(ySize>dim.height) ySize= dim.height; tx.append("\n"+xSize+ "," + ySize); f.setSize(xSize,ySize); } f.validate(); // so that Layout Manager ... } /* actionPerformed */} /* public class GiGi */



Run the GiGi.java Press the Bigger button



Press the 111 button



Press the ElevenEleven button



Press the Bigger button again



GiGi2.java: A VERY Simple Applicationimport java.awt.*;import java.awt.event.*;public class GiGi2 { Frame f = new Frame("Window 2002"); Button b1, b2, b3; Panel p; Button n; public static void main( String s[ ]) { new GiGi2( ); /* so that easily to change to Applet */ } public GiGi2( ) { // Constructor f.setSize(300,200); b1=new Button("111"); b2=new Button("222"); p = new Panel(); n= new Button("HahaHehehe"); p.add(n); n.setBackground(Color.green); f.add(b1,"West"); f.add(b2,"East"); f.add(p,"South"); /* Frame uses Boarder Layout manager */ f.show( ); }}

If you don’t understand the previous example, try this simple one!



Run the GiGi2.java

javac GiGi2.java

java GiGi2



GiGi3.java – stepwise refinement (p1/2)

import java.awt.*;

import java.awt.event.*;

public class GiGi3 implements ActionListener{

Frame f = new Frame("Window 2003");

Button b1,b2,b3;

Panel p; Button n;

public static void main( String s[ ]) {

new GiGi3(); /* easy to change to Applet */

}

Let us add event handler



GiGi3.java (p2/2) public GiGi3( ) { // Constructor f.setSize(300,200); b1=new Button("111"); b2=new Button("222"); p = new Panel( ); f.add(p,"South"); f.add(b1,"West"); f.add(b2,"East"); Button bq = new Button("Quit"); n= new Button("HahaHehehe"); p.add(n); p.add(bq); n.setBackground(Color.green); n.addActionListener(this); b1.addActionListener(this); f.show(); } public void actionPerformed (ActionEvent evt){ if(evt.getSource() == n){ n.setBackground(Color.red); n.setLabel(" 777 ");} if(evt.getSource() == b1) n.setLabel("Eleven"); f.show(); // so that Layout Manager ... }} Let us add event handler



Run the GiGi3.java

javac GiGi2.java

java GiGi2

What will happen if we press the "111" button?



Run the GiGi3.java (cont.)

按 "Quit" 有用嗎 ?



JDK : J2SDKhttp://java.sun.com/j2se/





http://java.sun.com/javase/downloads/index.jsp



JDK Installed Directory TreeThe JDK has the directory structure shown below.

jdk1.5.0_<version> _______________________|______________________ | | | | | | | | | | | | | bin lib | demo || | | LICENSE | | | jre| | COPYRIGHT … … | __|__| README.txt include | |

readme.html bin lib



工欲善其事 , 必先利其器http://www.csie.nctu.edu.tw/document/java/

或是舊交大資工網頁資源服務網路資源 Java 的說明書http://www.cs.nctu.edu.tw/ (新交大資工網頁 )相關連結網路資源 Java 的說明書





Java IDE

Best Java IDE Borland JBuilder, Borland Software Eclipse, Eclipse.org IntelliJ IDEA, JetBrains



Features of most IDE:

Full documentation of Java libraries at hand.

Can insert templates.

Syntax coloring.

Can indent program and find the matching brace.

Can easily comment-out code fragments.

Good printing facilities.

Syntax errors are highlighted (even if another file needs to be opened).

… and it does not interfere in your programming!

Ready-4



Java-XML tools

Best Java-XML Tool JAXB (Java Architecture for XML Binding),

Sun Microsystems Xalan-Java 2.5, The Apache XML Project Xerces2 Java Parser 2.4, The Apache XML

Project



Introduction to Java Programming

謝謝捧場http://www.csie.nctu.edu.tw/~tsaiwn/java/

蔡文能

Documents

交通大學資訊工程學系 Programming in Java Getting Started 蔡文能 交通大學資訊工程學系 [email protected] tsaiwn/java//java

交通大學資訊工程學系 Programming in Java Getting Started 蔡文能交通大學資訊工程學系 [email protected] tsaiwn/java//java