JAVA PROGRAMMING

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JAVA PROGRAMMING

• PART I

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?????????????

• ???????????????????????????????????????????(Sun
  Microsystems)
• ???? JAVA ??????????????????????????????????????
  ?????????????????
• ??????????????????????????????????????????????????
  ????
• ?????????????? ???????????????????????????????????
  ???????????????????????????????????
• ???????????????????????????????
  ??????????????????????????????????????????????????
  ? ????????????????????????????????????????????????

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Sun Microsystems
????????? 1990 ???????????????????
??????????????????????????????????????????????????
??????????????????????????? ? ?????? Sun
Microsystems ?????????????????????????????????????
????????????????????????????? ????????????????????
??????????????? ??????????????????
??????????????????????????????????????????????????
?????????? ????????? Green Group ???????? 1991 ??
James Gosling ????????????????????????????????????
?????????????????????????????????
???????????????????????????????????? Star7
???????? remote control ?????????? ????????? C
???????????? Star7 ???????????????????????????????
?????????????????????? ? ????????? C
????????????????? ???????????????????????? ????
????????????????????????????????
?????????????????????? ???????????????????????????
???????????????? ??????????????????????????
????????????????????????????????? ???? Oak
?????????????????????????????????????????
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???????????????????
????????????? java 1.0 ???????? JDK 1.0
(??????????????????????????????????????)
?????????????????? C ?????? 20 ???? ??? java 1.1
???????????????????? ????????????? 2 ??????? java
1.0 ??????????? JDK 1.2 ??????????????????????
Java 2 SDK 1.2 (Software Development Kit)
?????????????????????????? Java 2 SDK 1.4
???????????????????????? Java ????????????????????
???? ?????????????????????????????????????????????
?????????? ???????????????????? ????????? Just in
Time (JIT) compiler ??????????????????
????????????? ????????????????????????????????????
?????????????? ??????????????? ???????????????????
???????????????????, Java HotSpot (??????????
java 2 SDK 1.3) ??????????????????????????????????
?????????????? Java chip ???????????????
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??????????????????

• ??????????????????????? ??????????????????????????
  ??????????? (OOP Object Oriented Programming)
• Java ??? platform independence ???????????????????
  ???????????????????????? java ????????????????????
  ???????????????????? ??????????????????????
• Java ?? garbage collector ???????????? robust
• Java ????????????????????? C ???????????????????
  ????? 4 ???? ???????????????????????????(developme
  nt time) ???????? C ???????????????????????? 2
  ????
• Java ????????????????????????????????????????
  ?????? electronic signature, public and private
  key management, access control ??? certificates

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Definition of JAVA

• 2 appropriate definition for java
• Java is programming language
• Java is platform
• 2 forms of java
• Java application
• Java applet
• Java script is not java, it is developed by
  Netscape that used in web and base on java.

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Platform

• Platforms like Operating System
• All application must depend on platform
• Platform use for communicating with computer
  machine directly.

Example Microsoft Word run on Microsoft Window
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Java is Platform

• Java have own platform, named java virtual
  machine
• So, java can run on any OS because of java
  virtual machine.

Write Once, Run anywhere
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Java platform
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??????????????????
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??????????????????????

• Java program ?????????????????????????????????????
  ?? ????????????????? (text) ????????????????
  ?????????????????????? .java ???????????
  ????????? (Source code) ??????????????????????????
  ??? java class file ???? ????????
  ??????????????????? .class ???????????????????????
  ?? java virtual Machine ??????
• API ????????????????????? ????????????????????????
  ????? system services ????????????????? ???? Java
  API ??????????? ready-made software components
  ???????????????????????? Java Virtual Machine
  ?????? Java API ??????????????????????

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??????????????????????
Java Program
C Program
compile
compile
Byte code
Machine code
Java Virtual Machine
Computer
interpret
Computer
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Java Virtual Machine

• ????????????????????????????????????????
  ??????????????? class loader ??? Execution engine
  
• Class loader ????????????? class ????????????????
  java API ?????? class loader ????????????????
• bootstrap class loader ???? system class loader
  ????????????????? java virtual machine ???
• User-defined class loader
• Execution Engine ???????????? ???? just in time,
  Adaptive optimizer

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Java Virtual Machine
Java Virtual Machine
Class loader
Java APIs class
User-defined Class
Byte code
Execution Engine
Native method
Operating System
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Starting with JAVA2

• Download java compiler from web
• Double click this icon to install java.

http//java.sun.com/j2se
Java virtual machine JRE (Java Runtime
Environment) Java Developer Kit JDK

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Java step

• Java compiler is required

Edit source code on textfile
ltFile-namegt.java
Compile source code
Run on Java Virtual Machine
ltFile-namegt.class
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How to install

• Double click icon of file that download
• Fill folder to install name C\java

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Your First Program in JAVA

• Edit file name Welcome1.java at C\Myjava

// A first program in Java. public class Welcome1
/ main method begins execution of
Java application / public static void main (
String args ) System.out.println(Welcom
e to Java Programming!) // end method
main // end class Welcome1
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Compile Run

• Go to DOS
• Go to directory C\Myjava
• Type command for compile java program
• Type command for run java

javac ltfile-namegt.java
java ltfile-namegt
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Compile Run (contd)
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Write Once Run Anywhere
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Java Application

• What name of this application is ?

// Printing multiple lines of text with a single
statement. public class Welcome_mline //
main method bigins execution of Java application
public static void main ( String args )
System.out.println(Welcome\nto\nJava\nProgrammin
g) // end method main // end class
Welcome_mline
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Java Application
// Printing multiple lines in a dialog box //
Java extension packages import javax.swing.JOption
Pane // import class JOptionPane public class
Welcome_dialog // main method begins
execution of Java application public static
void main ( String args )
JOptionPane.showMessageDialog( null,
Welcome to Java Programming)
System.exit(0) // terminate application //
end method main // end class Welcome_dialog
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Java Application
// An addition program. // Java extension
packages import javax.swing.JOptionPane //
import class JOptionPane public class Addition
// main method begins execution of Java
application public static void main( String
args ) String firstNumber // first
string entered by user String secondNumber
// second string entered by user int number1
// first number to add int number2
// second number to add int sum
// sum of number1 and number2 // read in
first number from user as a String
firstNumber JOptionPane.showInputDialog(Enter
Number1) // read in second number from
user as a String secondNumber
JOptionPane.showInputDialog(Enter Number2)
// convert numbers from type String to type int
number1 Integer.parseInt(firstNumber)
number2 Integer.parseInt(secondNumber) sum
number1 number2 // add two numbers
JOptionPane.showMessageDialog(null, the sum is
sum, Results, JOptionPane.PLAIN_MESSA
GE) System.exit(0) // terminate
application // end method main // end class
Addition
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Message Dialog types

• JOptionPane.ERROR_MESSAGE
• JOptionPane.INFORMATION_MESSAGE
• JOpitonPane.WARNING_MESSAGE
• JOpitonPane.QUESTION_MESSAGE
• JOptionPane.PLAIN_MESSAGE

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Java applet

• Java language that must perform under web browser
• There are 2 ways to run applet
• Command appletviewer
• HTML page

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Java applet

• Go to c\java\demo\applets
• Enter director TicTacToe
• You can see file-name example1.html
• Type command

Appletviewer ltfilenamegt
Example appletviewer example1.html
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Create Java applet

• Edit file-name HelloA.java

//HelloA.java // java core packages import
java.awt. // import all class public class
HelloA extends java.applet.Applet // draw
text on Applet's background public void
paint(Graphics g) // draw a String at x
25 and y 50 g.drawString("Hello",25,50)
// end method paint // end class HelloA
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Create Java applet

• Edit file-name HelloA.html
• Type command appletviewer HelloA.html

lt! HelloA.htmlgt lthtmlgt ltbodygt This is my
first Applet. ltapplet code"HelloA.class"
width200 height200gt lt/appletgt
lt/bodygt lt/htmlgt
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Java Applet