1 1. about swing 2. the applet framework 3. a first applet 4. swing applications 5. the swing event...

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1. About Swing2. The Applet Framework3. A first Applet4. Swing Applications5. The Swing Event model6. Containment hierarchies7. Swing Taxonomy

2

History

Goal : Library to support (G)UIs

Java 1.0 AWT • looks the same (“mediocre”) on all platforms• restrictive (e.g. only 4 fonts available)• not OO ! Java 1.1 AWT • OO event model • JavaBeans Component model

First shot : Abstract Window Toolkit (AWT)

3

History

• nickname : “Swing”• adds :

• plugable look-and-feel• many new components• “light-weight components”

no native code (-> better appearance !)• support for automatic code generation (GUI-builders)

Second (3 ?) shot : Java Foundation Classes (JFC)

4

Philosophy : MVC

Model-View-Control architecture

View Controller

Data ModelClass contains• data• computations

Class presentedto the user

Controls :• data model (change, compute, …)• how data is presented to user

5

Applet ?

= Small application run in browser environment

- security restrictions (e.g. no hard disk access)- slow to display (due to download)+ no installation (automatic latest code !)+ no catastrophe due to malicious code

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Applet - Browser interaction

Browser interprets HTML-page

<!DOCTYPE HTML PUBLIC "-//IETF//DTD HTML//EN"><html><head><title>Algoritmisch Denken en Programmeren</title><meta name="GENERATOR" content="Microsoft FrontPage 3.0"></head>

<body>

<h1 align="center">Algoritmisch Denken en Programmeren </h1><h2 align="center">academiejaar 2000 - 2001</h2>

<dir> <li>Lesgevers : Bart Dhoedt en Mario Pickavet</li> <li><a href="#Berichten aan studenten">Berichten aan studenten</a></li></body></html>

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Applet - Browser interaction

Special applet-tag :

parameters codebase : location of Applet class filecode : name of Applet class fileheight : height of Applet area (in pixels)width : width of Applet area (in pixels)

<applet codebase="http://www.atlantis.rug.ac.be/inforasi/applets" code=AnApplet width=100 height=100> </applet>

• browser allocates (width x height) area for Applet• starts execution of Applet

http://www.atlantis.rug.ac.be/infor1kan/applets





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Testing Applets ...

// <applet code=AnApplet width=100 height=100> </applet>

Appletviewer

• searches for <applet>-tag in text file• executes the Applet

Trick

Add to your *.java file :

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Applet Class

4 methods• init() : called once when Applet is created (performs layout)• stop() : called each time Applet goes out of window• start() : called each time Applet gets back into window• destroy() : called once when page is removed from browser

window

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Applet class

JApplet

+init()+stop()+start()+destroy()

M yJApplet

+init()+stop()+start()+destroy()

Brow serVM

controls

How to code a JApplet ?

• import appropriate packagesimport java.awt.*;import java.awt.event.*;import javax.swing.*;import javax.swing.event.*;

• make a public class, extending JApplet• override at least init()

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Coding Applets// <applet code=MyApplet width=100 height=100> </applet>import javax.swing.*;import javax.swing.event.*;

public class MyApplet extends JApplet {// class data// class operationspublic void init() {

}} // end of class MyApplet

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Hello World !

// Source File : FirstApplet.java// <applet code=FirstApplet width=100 height=100> </applet>

import javax.swing.*;import javax.swing.event.*;

public class FirstApplet extends JApplet {public void init() {

JLabel text = new JLabel("Our first Applet !");getContentPane().add(text);

}} // End of class FirstApplet

Test with appletviewer :

C:\> appletviewer FirstApplet.java

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Hello World !

Test with browser :

(1) construct HTML-file<html><head> <title> Illustration of an Applet running in a Browser </title></head><body>This is a first Applet :<hr><applet code=FirstApplet width=100 height=100> </applet><hr></body></html>

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Hello World !(2) RUN HTML-converter

<html><head> <title> Illustration of an Applet running in a Browser </title></head><body>This is a first Applet :<hr><OBJECT classid="clsid:8AD9C840-044E-11D1-B3E9-00805F499D93”WIDTH = 100 HEIGHT = 100 codebase="http://java.sun.com/products/plugin/1.3/jinstall-13-win32.cab#Version=1,3,0,0"><PARAM NAME = CODE VALUE = FirstApplet ><PARAM NAME="type" VALUE="application/x-java-applet;version=1.3"><PARAM NAME="scriptable" VALUE="false"><COMMENT><EMBED type="application/x-java-applet;version=1.3" CODE = FirstApplet WIDTH = 100 HEIGHT = 100 scriptable=false pluginspage="http://java.sun.com/products/plugin/1.3/plugin-install.html"><NOEMBED></COMMENT></NOEMBED></EMBED></OBJECT><hr></body></html>

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Hello World !

(3) Open browser and select generated html-file

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Applet Framework// Source File : AppletFramework.java// <applet code=AppletFramework width=500 height=100> </applet>import javax.swing.*;import javax.swing.event.*;public class AppletFramework extends JApplet {

private String labelText="<INIT>";JLabel text = new JLabel(labelText+" ");public void init() { getContentPane().add(text);

System.out.println("<INIT>");}public void stop() { labelText+="<STOP>";

text.setText(labelText); System.out.println("<STOP>");

}public void start() { labelText+="<START>";

text.setText(labelText); System.out.println("<START>");

}public void destroy() { labelText+="<DESTROY>";

text.setText(labelText); System.out.println("<DESTROY>");

}} // End of class AppletFramework

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Applications

• same possibilities as text applications• + graphical components• has main()-method !

How to code Applications ?

• code a class extending JFrame• include a public constructor, performing initialisation (cf. JApplet’s init() method !)• create an object of this class

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Applications

import javax.swing.*;import javax.swing.event.*;class MyApplication extends JFrame {

public MyApplication(String title) {super(title); // sets frame title// add operations here

}} // End of class MyApplication

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

MyApplication app=new MyApplication(”<Add title of application here.>");app.setSize(200,200); // sets width and height of frameapp.setVisible(true); // makes the frame visibleapp.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); // since JDK1.3 !

}} // End of class FirstApplicationTest

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Applications

JFram e

+JFram e(title : S tring)+setV isible(b : boolean)+setS ize(width : int, height : int)+setDefaultC loseOperation(operation : int)

+EXIT_ON_CLOSE : int

M yApplication

+MyApplication(title : S tring)

M yApplicationTest

+m ain(args : S tring[])

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A First Application

// Source File : FirstApplicationTest.javaimport javax.swing.*;import javax.swing.event.*;class FirstApplication extends JFrame {

public FirstApplication(String title) {super(title); // sets frame titlegetContentPane().add(new JLabel("Our first application !"));

}} // End of class FirstApplicationpublic class FirstApplicationTest { public static void main(String[] args) {

FirstApplication app=new FirstApplication("Title : Graphical Application.");app.setSize(200,200);app.setVisible(true);app.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); // since JDK1.3 !

}} // End of class FirstApplicationTest

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Concept

Swing componentclass

Application class

Interface class• presents component to user• intercepts user interaction

Instantiates Swing components

Code to act upon user input ? ListenerObject

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Concept

Swing componentclassApplication class

ListenerObject

Interface class• presents component to user• intercepts user interaction

• Instantiates • Swing components• Listener objects

Contains handling code

• makes connection between listener and Swing object

Calls back handling codeof all registered listeners

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Concept

JTextField

Application class

Listener Object

...

JTextField f = new JTextField(20);

Listen a = new Listen();

f.addActionListener(a);

public void actionPerformed(ActionEvent e) {// …

}

EN

TER

PR

ES

SE

D

ActionEvent object

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Concept

Listener object • Must implement interface agreed with Swing class generating event• JTextField, JButton requires ActionListener

class JTextField {Vector listen=new Vector();public void addActionListener(ActionListener a) {

listen.addElement(a);}private void fireEvents {

ActionEvent e = new ActionEvent();for(int i=0;i<listen.size();i++)

((ActionListener)listen.elementAt(i)).actionPerformed(e);}

}

Listener class usually implemented as inner class !

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Listener optionsOption 1 : Listener class named inner class

class ListenText extends JFrame {JLabel a = new JLabel("Please input text : ");JTextField f = new JTextField(25);ListenText(String title) {

super(title);Listen l = new Listen();Container cp=getContentPane();cp.setLayout(new GridLayout(1,2));cp.add(a);cp.add(f);f.addActionListener(l);

}private class Listen implements ActionListener {

public void actionPerformed(ActionEvent e) {System.out.println("ENTER PRESSED !");

}}

}

ListenerObject

Registration

ListenerClass

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Listener optionsOption 2 : Listener class named inner class

anonymous listener object


super(title);Container cp=getContentPane();cp.setLayout(new GridLayout(1,2));cp.add(a);cp.add(f);f.addActionListener(new Listen() );

}private class Listen implements ActionListener {

public void actionPerformed(ActionEvent e) {System.out.println("ENTER PRESSED !");

}}

}

ListenerClass

ListenerObject

Registration

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Listener optionsOption 3 : Listener class anonymous inner class

anonymous listener object


super(title);Container cp=getContentPane();cp.setLayout(new GridLayout(1,2));cp.add(a);cp.add(f);f.addActionListener(new ActionListener() {

public void actionPerformed(ActionEvent e) { System.out.println("ENTER PRESSED :"+f.getText());}

} );}

}

ListenerObject

ListenerClass

Registration

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Listener optionsOption 4 : Listener class anonymous inner class

named listener object


super(title);Container cp=getContentPane();cp.setLayout(new GridLayout(1,2));cp.add(a);cp.add(f);ActionListener l=new ActionListener() {

public void actionPerformed(ActionEvent e) { System.out.println("ENTER PRESSED :"+f.getText());}

};f.addActionListener(l);

}}

ListenerObject

ListenerClass

Registration

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Listener options

Named Anonymous

Named

Anonymous

• >1 objects of listener class• listener to > 1 Swing object

• >1 objects of listener class • listener to 1 Swing object

• 1 object of listener class• listener to >1 Swing object

• 1 object of listener class• listener to 1 Swing object

Lis

ten

er O

bje

ct

Listener Class

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Listeners

Construct a Swing application :• label shows text : “Put lower case text here : “• text field (width 30) to input text• when “ENTER” is pressed, text in text field is put in upper case

Use JTextField methods :• public void setText(String)• public String getText()

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Listenersclass UpperCase extends JFrame {

// UI-components UpperCase(String title) {

super(title);Container cp=getContentPane();cp.setLayout(new GridLayout(1,2));cp.add(a);cp.add(f);// ...

}}public class UpperCaseTest { public static void main(String[] args) { UpperCase app=new UpperCase("Change to Upper"); app.setSize(500,200); app.setVisible(true); app.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); }}

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Many listeners

Application object

Swing object

USE

RA

CTI

ON

Event Object

Listener object

Listener object

callback

callback

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Many listenersclass ManyListen extends JFrame {

JLabel a = new JLabel("Type your text : ");JTextField f = new JTextField(30);ManyListen(String title) {

super(title);Container cp=getContentPane();cp.setLayout(new GridLayout(1,2));cp.add(a); cp.add(f);f.addActionListener(new ActionListener() {

public void actionPerformed(ActionEvent e) {System.out.println("I'm listening ... ");

}});f.addActionListener(new ActionListener() {

public void actionPerformed(ActionEvent e) {System.out.println("Me too ... ");

}});

}}

Callback order ???

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Many listeners

Construct a Swing application :• label shows text : “Input text : “• text field (width 30) to input text• register array of listener

Listener object :• has a number• appends number to text in text field

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Many listeners

class ArrayListen extends JFrame {JLabel a = new JLabel("Type your text : ");JTextField f = new JTextField(30);ArrayListen(String title) {

super(title);int listenSize = 4;Container cp=getContentPane();cp.setLayout(new GridLayout(1,2));a.setFont(font);f.setFont(font);cp.add(a);cp.add(f);// ...

}// ...

}

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ONE listener

Application object

Swing object 1

USE

RA

CTI

ON

Listener object Swing object 2

Swing object 3

Event Object 1

Event Object 2

Event Object 3

callback

USE

RA

CTI

ON

callback

callback

USE

RA

CTI

ON

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ONE listener

Listener object• is called back by many objects• action should depend on originator

Use of Event-object

getSource() yields REFERENCE to event firing object

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ONE listenerclass OneListen extends JFrame {

JLabel first = new JLabel("Type your first name : ");JLabel last = new JLabel("Type your last name : ");JTextField firstName = new JTextField(30);JTextField lastName = new JTextField(30);OneListen(String title) {

super(title);Container cp=getContentPane();cp.setLayout(new GridLayout(2,2));cp.add(first);cp.add(firstName);cp.add(last);cp.add(lastName);ActionListener l=new ActionListener() { public void actionPerformed(ActionEvent e) { JTextField t=(JTextField)e.getSource(); if(t==firstName) { System.out.println("Input in first name.");

t.setText((t.getText()).toLowerCase()); } else { System.out.println("Input in last name.");

t.setText((t.getText()).toUpperCase()); } }};firstName.addActionListener(l); lastName.addActionListener(l);

}} Try to avoid type-checking code !

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ONE listener

Construct a Swing application :• array of text fields shown in a column• concatenation of text shown in label 1• sequence of text fields “entered” shown in label 2

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ONE listener

class ListenToArray extends JFrame {JLabel label1 = new JLabel("");JLabel label2 = new JLabel("");// ...ListenToArray(String title) {

super(title);int size=10;Container cp=getContentPane();// layout ???

// ...}

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Dynamic event binding

Listener objects can be• registered• deregistered

during program execution

addActionListener(…)

removeActionListener(…)

Example

• two listener objects “red” and “green”• only one listener active at given time• turns text in text field in color defined• switches to other colour

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Dynamic event bindingclass RedGreen extends JFrame {

JLabel label = new JLabel("Type your text here : ");JTextField text = new JTextField(30);ActionListener red,green;RedGreen(String title) {

super(title);Container cp=getContentPane();cp.setLayout(new GridLayout(1,2));text.setForeground(Color.green);cp.add(label);cp.add(text);red=new ActionListener() {public void actionPerformed(ActionEvent e) {

text.setForeground(Color.red);text.addActionListener(green);text.removeActionListener(red);

}};green=new ActionListener() {public void actionPerformed(ActionEvent e) {

text.setForeground(Color.green);text.addActionListener(red);text.removeActionListener(green);

}};text.addActionListener(red);

}}

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In general ...

• Swing Components can fire Events

• Registered listener objects are called

• Listener objects implement agreed interface

XxxEvent

addXxxListenerremoveXxxListener

XxxListener

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In general ...

XxxEvent

addXxxListener

XxxListener

Component JButton JCheckBox JFrame

ActionEvent ItemEvent WindowEvent

addActionListener addItemListener addWindowListener

ActionListener ItemListener WindowListener

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Example : JFrame

Listener Object must implement WindowListener interface

• public void windowOpened(WindowEvent e)• public void windowClosing(WindowEvent e)• public void windowClosed(WindowEvent e)• public void windowActivated(WindowEvent e)• public void windowDeactivated(WindowEvent e)• public void windowIconified(WindowEvent e)• public void windowDeiconified(WindowEvent e)

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Example : JFrameclass JFrameEvent extends JFrame {

JFrameEvent(String title) {super(title);}}public class JFrameEventTest { static JFrameEvent app=new JFrameEvent("Event Testing ..."); public static void main(String[] args) { app.setSize(200,100); app.setVisible(true); app.addWindowListener(new WindowListener() { public void windowOpened(WindowEvent e) {System.out.println("windowOpened");} public void windowClosing(WindowEvent e) {

System.out.println("windowClosing ...");app.dispose();}

public void windowClosed(WindowEvent e) {System.out.println("windowClosed ...");System.exit(0);}

public void windowActivated(WindowEvent e) {System.out.println("windowActivated");} public void windowDeactivated(WindowEvent e) {System.out.println("windowDeact.");} public void windowIconified(WindowEvent e) {System.out.println("windowIconified");} public void windowDeiconified(WindowEvent e) {System.out.println("windowDeicon.");} }); }}

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Adapter ClassesMotivation• some interfaces contain a lot of methods• in lot of situations : only a few are useful• other methods must be implemented• -> a lot of methods are dummy methods

Java trick • all interfaces with more than 1 method : adapter class with empty methods• inherit from adapter class, and only define methods you need

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Adapter ClassesExample : WindowListener

WindowListener

+windowO pened(e : W indowEvent) : vo id+windowC losing(e : W indowEvent) : vo id+windowC losed(e : W indowEvent) : vo id+windowActivated(e : W indowEvent) : vo id+windowDeactivated(e : W indowEvent) : vo id+windowIconified(e : W indowEvent) : vo id+windowDeiconified(e : W indowEvent) : vo id

MyWindow Listener

+windowO pened(e : W indowEvent) : vo id+windowC losing(e : W indowEvent) : vo id+windowC losed(e : W indowEvent) : vo id+windowActivated(e : W indowEvent) : vo id+windowDeactivated(e : W indowEvent) : vo id+windowIconified(e : W indowEvent) : vo id+windowDeiconified(e : W indowEvent) : vo id

Implementation without adapter class

public void windowOpened(WindowEvent e) { }…public void windowClosing(WindowEvent e) {

// things to do when window closes}…public void windowDeiconified(WindowEvent e) { }

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Adapter ClassesExample : WindowListenerWindowListener

+windowO pened(e : W indowEvent) : void+windowClosing(e : W indowEvent) : void+windowClosed(e : W indowEvent) : void+windowActivated(e : W indowEvent) : vo id+windowDeactivated(e : W indowEvent) : vo id+windowIconified(e : W indowEvent) : vo id+windowDeiconified(e : W indowEvent) : void

Window Adapter

+windowO pened(e : W indowEvent) : void+windowClosing(e : W indowEvent) : void+windowClosed(e : W indowEvent) : void+windowActivated(e : W indowEvent) : vo id+windowDeactivated(e : W indowEvent) : vo id+windowIconified(e : W indowEvent) : vo id+windowDeiconified(e : W indowEvent) : void

MyWindow Listener

+windowClosing(e : W indowEvent) : void

Implementation withadapter class

public void windowOpened(WindowEvent e) { }…public void windowClosing(WindowEvent e) {

// things to do when window closes}…public void windowDeiconified(WindowEvent e) { }

public void windowClosing(WindowEvent e) {// things to do when window closes

}

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Adapter ClassesExample : WindowListener

class WindowAdapterTest extends JFrame {WindowAdapterTest(String title) {

super(title);}

}public class AdapterTest { static WindowAdapterTest app=new WindowAdapterTest("Adapter Testing ..."); public static void main(String[] args) { app.setSize(200,100); app.setVisible(true);

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

System.out.println("We're leaving the application !!!");app.dispose();System.exit(0);

} }); }}

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Concept3 types of components

Top-level containers

Intermediary containers

Atomic components

• provide space for other Swing components• provide services for : layout and event handling• composed of menu bar and content pane (+ …)• examples : JFrame, JApplet, JDialog

• provide space for other Swing components• provide services for layout• example : JPanel

• can not hold other components• visible for user interaction (input/output)

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Top-level containers

Menu bar

Content Pane

Title bar

class Chooser extends JFrame {Chooser(String title) {

super(title);JMenuBar menuBar=new JMenuBar();JMenu[] menus = {new JMenu("File"),new JMenu("Edit")

,new JMenu("Search"),new JMenu("Help")};for(int i=0;i<menus.length;i++) menuBar.add(menus[i]);setJMenuBar(menuBar);

}} Not added to the content Pane

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Containers

• can hold other componentscreating a “containment” hierarchy

• components held controlled by• add(…)• remove(…)

• layout controlled by own layout manager• setLayout(LayoutManager l);• doLayout(); (force layouting)

54

Containers

Construct a Swing application (without event handlers),showing following layout :

JTextArea object

55

Containers

Containment hierarchyJFrame

Content Pane

JPanel light

JPanel buttons

JTextArea a JButtongreen

JButtonorange

JButtonred

56

Containers

class Traffic extends JFrame {JPanel light;JTextArea show = new JTextArea(“ \n\n\n”);;Traffic(String title) {

super(title);Container cp=getContentPane();// ...

}}

JFrame

Content Pane

JPanel light

JPanel buttons

JTextArea a JButtongreen

JButtonorange

JButtonred

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Forcing layoutexample

class ForceLayout extends JFrame {Vector buttons = new Vector();Container cp;ForceLayout(String title) {

super(title);cp=getContentPane();cp.setLayout(new FlowLayout());JButton add = new JButton("Add a button");cp.add(add);add.addActionListener(new ActionListener() {

public void actionPerformed(ActionEvent e) {JButton b=new JButton("Button "+buttons.size());buttons.addElement(b);cp.add(b);

cp.doLayout();}

});}

}

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Forcing Layout

Extend the previous example :• add a remove button• organize all buttons in 2 columns

59

Abstract Window Toolkit

The awt-package

java.aw t

Component

applet

Applet

Panel

Container

Window

Frame

Button

CheckBox

TextField

AWTEvent

event

Ato

mic

co

mp

on

en

ts

“containing” components

60

Events

The awt.event-package

java.aw t.event

AWTEvent

ActionEvent

Window Event

EventListener

ActionListener

WindowListener

61

Awt - Swing connection

java.aw t.Component

java.aw t.Container

javax.sw ing.JComponent

• hints for layouting (object size)• external representation of component (paint)• handling events associated with component

• add/remove components• perform layout (setLayout, doLayout)• decide when to (re)paint component

• parent class of all J******* classes except top-level containers• services to child classes :

• tooltips, borders, pluggable look&fee, layout support, ...

62

Swing java.aw t.Component

applet

Applet

java.aw t.Panel

java.aw t.Container

java.aw t.Window

java.aw t.Frame

javax.sw ing.JComponent

javax.sw ing.JWindow

javax.sw ing.JFrame

javax.sw ing.JApplet

javax.sw ing.JPanel

java.aw t.Dialog

javax.sw ing.JDialog

Atomicawt-components

Top-levelSwing containers

All otherSwing components

1 1. about swing 2. the applet framework 3. a first applet 4. swing applications 5. the swing event...

Documents

import javax

applet class fileheight

time applet

applet framework3

public class appletframework

public class firstapplet

public class myapplet

swing event model6