cs423 java intro bw

8/12/2019 Cs423 Java Intro Bw

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Intro to Java

Java Applications

Swing Class

Graphics


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Java Outline

Today

Intro and Applications

GUI

Client / Server

RMI, JDBC

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JAVA Implementation

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Java program

Java program

VM

Java Cmds

Java program

VM

Java Cmds

Java program

VM

Java Cmds

SPARC PowerPC Intel


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Operations Environments

Applications program (~DOS window)

supports file access

Applet (browser)

no longer generally supported

supports Internet linkages.

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Building Java ApplicationsUsing Java Development Kit

Get a copy of the JDK (www.oracle.com, etc.)

Install the development kit (tools and classes)

Create MyApp.java source file

text editor (notepad, etc.)

winedit, Caf, etc.

Compile .java file to create .class file

javac MyApp.java Run application (.class file) through java VM

java MyApp

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Building Java ApplicationsUsing Java IDEs

NetBeans Available from netbeans.org

Eclipse Available from www.eclipse.org

jCreator le available from jcreator.com

jcreator proacademic license $35

jDeveloper available from www.oracle.com/technetwork/developer-

tools/jdev

many others


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Sample Java App

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G:\Data\Java\MyHelloApp>type MyHelloApp.javaclass MyHelloApp

{

public static void main (String argv[]){String message[] = new String[2];

message[0] = "Welcome to CS423";message[1] = "The subject is JAVA!";

System.out.println (message[0]);System.out.println (message[1]);

}}


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MyHelloApp Implementation

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MyHelloApp.java

MyHelloApp.class

VM

machine code

MyHelloApp.class

Java compiler

Java byte code


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Sample Java App

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G:\Data\Java\MyHelloApp>javac MyHelloApp.java

G:\Data\Java\MyHelloApp>java MyHelloApp

Welcome to CS423The subject is JAVA!

G:\Data\Java\MyHelloApp>


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MyHelloApp.class


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Get Input from User

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import java.io.*;

class InputApp{

InputApp (){DataInputStream dis = new DataInputStream (System.in);String sIn = " ";String sOut = " ";File fIn;

File fOut;FileInputStream fis;FileOutputStream fos;int iNumBytesRead;

byte[] ab;


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Get Input from User

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System.out.println("*-------------------------------------------*");

System.out.print ("Enter Source File Name Here: ");System.out.flush ();

try {sIn = dis.readLine ();}catch (Exception e)

{System.out.println ("Exception on input file name"+ e);}

System.out.print("Enter Destination File Name Here: ");System.out.flush ();

try {sOut = dis.readLine ();}catch (Exception e)

{System.out.println ("Exception on output file name"+ e);}


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Get Input from User

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try{fIn = new File (sIn);fis = new FileInputStream (fIn);

fOut = new File (sOut);fos = new FileOutputStream (fOut);ab = new byte[2048];

while ((iNumBytesRead = fis.read (ab)) != -1){ fos.write (ab, 0, iNumBytesRead); }

fis.close ();

fos.close ();}

catch (Exception e){System.out.println ("Exception during copy: " + e); }


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Get Input from User

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System.out.println ("Data copied from " + sIn + " to "+ sOut);

System.out.println

("*-------------------------------------------*");}

public static void main (String args[]){new InputApp ();

}}


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Get Input from User

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G:\Data\Java\InputApp>java InputApp*-------------------------------------------*

Enter Source File Name Here: books_db.txtEnter Destination File Name Here: My_list.txtData copied from books_db.txt to My_list.txt*-------------------------------------------*

G:\Data\Java\InputApp>


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Swing Components

Defined in package javax.swing

Pure Java components

AWT components tied to local platform GUI

UNIX java windows look like X windows

Windows java windows look like Windowswindows (??)

etc. Swing defines a common look and feel for

Java.


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Product.java

// From Java: How to Program - Deitel and Deitel

// Calculate the product of three integers

import javax.swing.JOptionPane;

public class Product {

public static void main( String args[] )

{

int x, y, z, result;

String xVal, yVal, zVal;

xVal = JOptionPane.showInputDialog(

"Enter first integer:" );

yVal = JOptionPane.showInputDialog("Enter second integer:" );

zVal = JOptionPane.showInputDialog(

"Enter third integer:" );


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Product.java

x = Integer.parseInt( xVal );

y = Integer.parseInt( yVal );

z = Integer.parseInt( zVal );

result = x * y * z;

JOptionPane.showMessageDialog( null,

"The product is " + result );

System.exit( 0 );

}

}


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Product Output(s)


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JOptionPane

Similar to windows message boxes

Types of Option Panes:

showConfirmDialog(null,message,title,optionType,msgType);

Asks a confirming question, like yes/no/cancel.

showInputDialog(message);

Prompt for some input.

showMessageDialog(null, message);Tell the user about something that has happened.

showOptionDialog(....);

The Grand Unification of the above three.

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Additional Swing Options

JOptionPane.showMessageDialog(null, "This is an alert",

"Alert", JOptionPane.ERROR_MESSAGE);

JOptionPane.showConfirmDialog(null,

"Is that your final answer?", "Choice Dialog",

JOptionPane.YES_NO_OPTION);


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Object[] options = { "Lady", "Tiger" };

choice = JOptionPane.showOptionDialog(null,

"What will it be -\nThe Lady or the Tiger?", "Decision",

JOptionPane.DEFAULT_OPTION, JOptionPane.QUESTION_MESSAGE,

null, options, options[0]);

if (choice == 0)JOptionPane.showMessageDialog( null, "You chose the Lady",

"Result", JOptionPane.PLAIN_MESSAGE );

else

JOptionPane.showMessageDialog( null, "You chose the Tiger",

"Result", JOptionPane.PLAIN_MESSAGE );


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Object[] possibleValues = { "First", "Second", "Third" };

Object selectedValue = JOptionPane.showInputDialog(null,

"Choose one", "Input", JOptionPane.INFORMATION_MESSAGE,

null, possibleValues, possibleValues[0]);


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Graphics in Applications

Must include a main()method

Must extend the AWT Frameclass, or swing

JFrameclass

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HelloWorldWindow

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import java.awt.*;import java.awt.event.*;

public class HelloWorldWindow implements WindowListener{

public HelloWorldWindow(){

myFrame f=new myFrame();f.addWindowListener (this);

}

public void windowClosing(WindowEvent e) {System.out.println ("Closing Window");System.exit(0);

}


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HelloWorldWindow

class myFrame extends Frame{myFrame(){

this.setSize(300, 200);this.show();

}

public void paint(Graphics g){

String str = "A Windows version of Hello, World";g.drawString(str, 25, 75);

}public static void main(String[] args){ Frame f = new HelloWorldWindow();

f.resize(300, 200);f.show();

}}

}


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HelloWorldWindow Output


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public void paint (Graphics g)

Provides an initial presentation of Graphics

Works on Graphics object

(like device context). Place to store settings for screen output (text,

images. etc.)

Must be regenerated following changes.

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Event Driven Programming

Operating System recognizes an event

Sends a signal to appropriate object

Object receives event notification and callsappropriate function

public void windowClosing(WindowEvent e) {

System.out.println ("Closing Window");

System.exit(0);

}

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Object Layout

BorderLayout (default for Frames)

FlowLayout (default for Panels)

GridLayout GridbagLayout

CardLayout

Fixed: object.reshape (x, y, width, height);

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nuTextTest Example

Linux

Windows


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NuTextTest2.java

import javax.swing.*;import java.awt.*;import java.awt.event.*;

public class NuTextTest2 extends JFrame {public NuTextTest2() {

setTitle("NuTextTest2");Container p = getContentPane();p.setLayout(new FlowLayout());TickButton = new Button("Tick");p.add(TickButton);TickButton.addActionListener(new ActionListener() {public void actionPerformed (ActionEvent e) {

int minutes = Integer.parseInt(minuteField.getText());minutes += 1;String min = String.valueOf(minutes);minuteField.setText(min);

}} //end of ActionListener); //end of TickButton


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NuTextTest2.java

SetTime = new Button("Set Time");p.add(SetTime);SetTime.addActionListener(new ActionListener()

{public void actionPerformed (ActionEvent e){

String tim = hourField.getText()+ ":" +minuteField.getText();

timeField.setText(tim);

}}

);


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NuTextTest2.java

hourField = new TextField("12", 3);p.add(hourField);minuteField = new TextField("00", 3);p.add(minuteField);timeField = new TextField("", 12);

p.add(timeField);

setSize (400,100);show ();

}//end of NuTextTest2 (constructor)

private TextField hourField;private TextField minuteField;private TextField timeField;private Button TickButton;private Button SetTime;


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NuTextTest2.java

public static void main(String[] args){

NuTextTest2 app = new NuTextTest2();

app.addWindowListener(new WindowAdapter() {public void windowClosing( WindowEvent e ){

System.exit( 0 );}

});

}//end of main()}//end of program


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Summary

Java is:

Platform independent

Object-oriented

Dynamic

Flexibleused in many different domains

Command line or graphical

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