Java Swing AWT to Swing GUI Component API Using a GUI ...

AWT to Swing Java Swing

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AWT: Abstract Windowing Toolkit

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Swing: new with Java2

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API: „

GUI Component API

import java.awt.*

import javax.swing.* Extends AWT Many new improved components Standard dialog boxes, tooltips, … Look-and-feel, skins Event listeners http://java.sun.com/j2se/1.3/docs/api/index.html

Using a GUI Component

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Java: GUI component = class

1.

Create it

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Properties

2.

Configure it

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JButton

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Methods

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Add it

4.

Listen to it

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Events „

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Anatomy of an Application GUI GUI

JFrame JPanel

JFrame JButton

2. 3. 4.

containers

5.

JPanel

panel.add(b);

[avoided in java]

JButton

Events: Listeners

Using a GUI Component 2 1.

Internal structure

Properties: b.text = “press me”; Methods: b.setText(“press me”);

3.

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Instantiate object: b = new JButton(“press me”);

Create it Configure it Add children (if container) Add to parent (if not JFrame) Listen to it

order important

JLabel JButton

JLabel

1

Build from bottom up „

Create: „ „ „ „

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Frame Panel Components Listeners

JLabel

Add: (bottom up) „ „ „

Code

Listener

JFrame f = new JFrame(“title”); JPanel p = new JPanel( ); JButton b = new JButton(“press me”);

JButton

p.add(b); // add button to panel f.setContentPane(p); // add panel to frame

JPanel

listeners into components components into panel panel into frame

f.show();

press me JFrame

Application Code

Layout Managers

import javax.swing.*;

„ class hello { public static void main(String[] args){ JFrame f = new JFrame(“title”); JPanel p = new JPanel(); JButton b = new JButton(“press me”);

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Automatically control placement of components in a panel Why? „

p.add(b); f.setContentPane(p);

// add button to panel // add panel to frame

f.show();

press me

} }

Layout Manager Heuristics null none, programmer sets x,y,w,h

FlowLayout

Layout Manager Heuristics

GridLayout BorderLayout n

Left to right, Top to bottom

w

c

e

CardLayout

One at a time

GridBagLayout

JButton

s

2

Coordinate System „

Component Hierarchy „

Upside-down Cartesian

Each component has its own subwindow „ „

(0,0)

(width,0)

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Subwindow = rectangular area within parent component Has own coordinate system

Clipping: „ „

Can’t paint outside its subwindow Can’t paint over child components?

JPanel

(0,0) (0,height) „

(width, height)

JButton

(0,0) JButton

(wb, hb)

Ywindow = height - Ycartesian

(wp, hp)

Combinations

Combinations JButton

JButton

JFrame

JButton JButton

n

JPanel: FlowLayout

JPanel: BorderLayout JTextArea

c JTextArea

Code: null layout

Code: FlowLayout

JFrame f = new JFrame(“title”); JPanel p = new JPanel( ); JButton b = new JButton(“press me”); b.setBounds(new Rectangle(10,10, 100,50)); p.setLayout(null); // x,y layout p.add(b); f.setContentPane(p);

press me

JFrame f = JPanel p = FlowLayout JButton b1 JButton b2

new JFrame(“title”); new JPanel( ); L = new FlowLayout( ); = new JButton(“press me”); = new JButton(“then me”);

p.setLayout(L); p.add(b1); p.add(b2); f.setContentPane(p);

press me then me

Set layout mgr before adding components

3

Applets „ „

Applet Methods

JApplet is like a JFrame Already has a panel „

JApplet

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Access panel with JApplet.getContentPane( ) „

contentPane

import javax.swing.*;

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class hello extends JApplet { public void init(){ JButton b = new JButton(“press me”); getContentPane().add(b); } }

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JButton

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Called by browser: init( ) start( ) stop( ) destroy( ) paint( )

Application + Applet import javax.swing.*; class helloApp { public static void main(String[] args){ // create Frame and put my mainPanel in it JFrame f = new JFrame(“title”); mainPanel p = new mainPanel(); f.setContentPane(p); f.show(); } }

Command line

Browser

JFrame

JApplet contentPane

class helloApplet extends JApplet { public void init(){ // put my mainPanel in the Applet mainPanel p = new mainPanel(); getContentPane().add(p); } } // my main GUI is in here: class mainPanel extends JPanel { mainPanel(){ setLayout(new FlowLayout()); JButton b = new JButton(“press me”); add(b); } }

Applet Security „

or

- initialization - resume processing (e.g. animations) - pause - cleanup - redraw stuff (‘expose’ event)

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No read/write on client machine Cannot execute programs on client machine Communicate only with server “Java applet window” Warning

JPanel JButton

4