1. Chapter 13 – Graphical User Components Part 2
Outline
Introduction JTextArea Creating a Customized Subclass of JPanel Creating a Self-Contained Subclass of JPanel JSlider Windows Designing Programs that Execute as Applets or Applications Using Menus with Frames Using JPopupMenus Pluggable Look-and-Feel Using JDesktopPane and JInternalFrame Layout Managers BoxLayout Layout Manager CardLayout Layout Manager GridBagLayout Layout Manager GridBagConstraints Constants RELATIVE and REMAINDER (Optional Case Study) Thinking About Objects: Model-View- Controller

2. Chapter 13 – Graphical User Components Part 2
(Optional) Discovering Design Patterns: Design Patterns Used in Packages java.awt and javax.swing Creational Design Patterns Structural Design Patterns Behavioral Design Patterns Conclusion

3. Advanced GUI components
Introduction
Advanced GUI components
Text areas
Sliders
Menus
Advanced layout managers
BoxLayout
CardLayout
GridBagLayout

4. 13.2 JTextArea JTextArea Area for manipulating multiple lines of text
Inherits from JTextComponent

5. TextAreaDemo.java Line 20 Lines 22-29
1 // Fig. 13.1: TextAreaDemo.java
2 // Copying selected text from one text area to another. 3
4 // Java core packages
5 import java.awt.*;
6 import java.awt.event.*; 7
8 // Java extension packages
9 import javax.swing.*; 10
11 public class TextAreaDemo extends JFrame {
private JTextArea textArea1, textArea2;
private JButton copyButton; 14
// set up GUI
public TextAreaDemo() {
super( "TextArea Demo" ); 19
Box box = Box.createHorizontalBox(); 21
String string = "This is a demo string to\n" +
"illustrate copying text\n" +
"from one TextArea to \n" +
"another TextArea using an\n" + "external event\n"; 26
// set up textArea1
textArea1 = new JTextArea( string, 10, 15 );
box.add( new JScrollPane( textArea1 ) ); 30
// set up copyButton
copyButton = new JButton( "Copy >>>" );
copyButton.addActionListener( 34
TextAreaDemo.java Line 20 Lines 22-29
Create Box container for organizing GUI components
Populate JTextArea with String, then add to Box

6. TextAreaDemo.java Lines 40-43 Lines 52-53
// anonymous inner class to handle copyButton event
new ActionListener() { 37
// set text in textArea2 to selected
// text from textArea1
public void actionPerformed( ActionEvent event ) {
textArea2.setText( textArea1.getSelectedText() ); } 44
} // end anonymous inner class 46
); // end call to addActionListener 48
box.add( copyButton ); 50
// set up textArea2
textArea2 = new JTextArea( 10, 15 );
textArea2.setEditable( false );
box.add( new JScrollPane( textArea2 ) ); 55
// add box to content pane
Container container = getContentPane();
container.add( box ); // place in BorderLayout.CENTER 59
setSize( 425, 200 );
setVisible( true ); } 63
// execute application
public static void main( String args[] ) {
TextAreaDemo application = new TextAreaDemo(); 68
TextAreaDemo.java Lines Lines 52-53
When user presses JButton, textArea1’s highlighted text is copied into textArea2
Instantiate uneditable JTextArea

7. TextAreaDemo.java Program Output
application.setDefaultCloseOperation(
JFrame.EXIT_ON_CLOSE ); } 72
73 } // end class TextAreaDemo
TextAreaDemo.java Program Output

8. 13.3 Creating a Customized Subclass of JPanel
Extend JPanel to create new components
Dedicated drawing area
Method paintComponent of class JComponent

9. CustomPanel.java Lines 12 Lines 15-23 Line 29
1 // Fig. 13.2: CustomPanel.java
2 // A customized JPanel class. 3
4 // Java core packages
5 import java.awt.*; 6
7 // Java extension packages
8 import javax.swing.*; 9
10 public class CustomPanel extends JPanel {
public final static int CIRCLE = 1, SQUARE = 2;
private int shape; 13
// use shape to draw an oval or rectangle
public void paintComponent( Graphics g ) {
super.paintComponent( g ); 18
if ( shape == CIRCLE )
g.fillOval( 50, 10, 60, 60 );
else if ( shape == SQUARE )
g.fillRect( 50, 10, 60, 60 ); } 24
// set shape value and repaint CustomPanel
public void draw( int shapeToDraw ) {
shape = shapeToDraw;
repaint(); } 31
32 } // end class CustomPanel
CustomPanel.java Lines 12 Lines Line 29
Store integer representing shape to draw
Override method paintComponent of class JComponent to draw oval or rectangle
Method repaint calls method paintComponent

10. CustomPanelTest.java Lines 22-23
1 // Fig. 13.3: CustomPanelTest.java
2 // Using a customized Panel object. 3
4 // Java core packages
5 import java.awt.*;
6 import java.awt.event.*; 7
8 // Java extension packages
9 import javax.swing.*; 10
11 public class CustomPanelTest extends JFrame {
private JPanel buttonPanel;
private CustomPanel myPanel;
private JButton circleButton, squareButton; 15
// set up GUI
public CustomPanelTest() {
super( "CustomPanel Test" ); 20
// create custom drawing area
myPanel = new CustomPanel();
myPanel.setBackground( Color.green ); 24
// set up squareButton
squareButton = new JButton( "Square" );
squareButton.addActionListener( 28
// anonymous inner class to handle squareButton events
new ActionListener() { 31
CustomPanelTest.java Lines 22-23
Instantiate CustomPanel object and set background to green

11. CustomPanelTest.java Lines 33-36 Lines 49-52 Line 60
// draw a square
public void actionPerformed( ActionEvent event ) {
myPanel.draw( CustomPanel.SQUARE ); } 37
} // end anonymous inner class 39
); // end call to addActionListener 41
circleButton = new JButton( "Circle" );
circleButton.addActionListener( 44
// anonymous inner class to handle circleButton events
new ActionListener() { 47
// draw a circle
public void actionPerformed( ActionEvent event ) {
myPanel.draw( CustomPanel.CIRCLE ); } 53
} // end anonymous inner class 55
); // end call to addActionListener 57
// set up panel containing buttons
buttonPanel = new JPanel();
buttonPanel.setLayout( new GridLayout( 1, 2 ) );
buttonPanel.add( circleButton );
buttonPanel.add( squareButton ); 63
When user presses squareButton, draw square on CustomPanel
CustomPanelTest.java Lines Lines Line 60
When user presses circleButton, draw circle on CustomPanel
Use GridLayout to organize buttons

12. CustomPanelTest.java Program Output
// attach button panel & custom drawing area to content pane
Container container = getContentPane();
container.add( myPanel, BorderLayout.CENTER );
container.add( buttonPanel, BorderLayout.SOUTH ); 68
setSize( 300, 150 );
setVisible( true ); } 72
// execute application
public static void main( String args[] ) {
CustomPanelTest application = new CustomPanelTest(); 77
application.setDefaultCloseOperation(
JFrame.EXIT_ON_CLOSE ); } 81
82 } // end class CustomPanelTest
CustomPanelTest.java Program Output

13. 13.4 Creating a Self-Contained Subclass of JPanel
Does not support conventional events
e.g., events offered by buttons, text areas, etc.
Capable of recognizing lower-level events
e.g., mouse events, key events, etc.
Self-contained panel
Listens for its own mouse events

14. SelfContainedPanel.java Line 20 Lines 29-30
1 // Fig. 13.4: SelfContainedPanel.java
2 // A self-contained JPanel class that
3 // handles its own mouse events.
4 package com.deitel.jhtp4.ch13; 5
6 // Java core packages
7 import java.awt.*;
8 import java.awt.event.*; 9
10 // Java extension packages
11 import javax.swing.*; 12
13 public class SelfContainedPanel extends JPanel {
private int x1, y1, x2, y2; 15
// set up mouse event handling for SelfContainedPanel
public SelfContainedPanel() {
// set up mouse listener
addMouseListener( 21
// anonymous inner class for mouse pressed and
// released event handling
new MouseAdapter() { 25
// handle mouse press event
public void mousePressed( MouseEvent event ) {
x1 = event.getX();
y1 = event.getY(); } 32
SelfContainedPanel.java Line 20 Lines 29-30
Self-contained JPanel listens for MouseEvents
Save coordinates where user pressed mouse button

15. SelfContainedPanel.java Lines 36-38 Line 46 Lines 54-56
// handle mouse release event
public void mouseReleased( MouseEvent event ) {
x2 = event.getX();
y2 = event.getY();
repaint(); } 40
} // end anonymous inner class 42
); // end call to addMouseListener 44
// set up mouse motion listener
addMouseMotionListener( 47
// anonymous inner class to handle mouse drag events
new MouseMotionAdapter() { 50
// handle mouse drag event
public void mouseDragged( MouseEvent event ) {
x2 = event.getX();
y2 = event.getY();
repaint(); } 58
} // end anonymous inner class 60
); // end call to addMouseMotionListener 62
} // end constructor 64
Save coordinates where user released mouse button, then repaint
SelfContainedPanel.java Lines Line 46 Lines 54-56
Self-contained JPanel listens for when mouse moves
Save coordinates where user dragged mouse, then repaint

16. SelfContainedPanel.java Lines 76-77
// return preferred width and height of SelfContainedPanel
public Dimension getPreferredSize() {
return new Dimension( 150, 100 ); } 70
// paint an oval at the specified coordinates
public void paintComponent( Graphics g ) {
super.paintComponent( g ); 75
g.drawOval( Math.min( x1, x2 ), Math.min( y1, y2 ),
Math.abs( x1 - x2 ), Math.abs( y1 - y2 ) ); } 79
80 } // end class SelfContainedPanel
SelfContainedPanel.java Lines 76-77
Draw oval

17. SelfContainedPanelTest.java Lines 24-25 Line 32
1 // Fig. 13.5: SelfContainedPanelTest.java
2 // Creating a self-contained subclass of JPanel
3 // that processes its own mouse events. 4
5 // Java core packages
6 import java.awt.*;
7 import java.awt.event.*; 8
9 // Java extension packages
10 import javax.swing.*; 11
12 // Deitel packages
13 import com.deitel.jhtp4.ch13.SelfContainedPanel; 14
15 public class SelfContainedPanelTest extends JFrame {
private SelfContainedPanel myPanel; 17 18
// set up GUI and mouse motion event handlers for
// application window
public SelfContainedPanelTest() {
// set up a SelfContainedPanel
myPanel = new SelfContainedPanel();
myPanel.setBackground( Color.yellow ); 26
Container container = getContentPane();
container.setLayout( new FlowLayout() );
container.add( myPanel ); 30
// set up mouse motion event handling
addMouseMotionListener( 33
// anonymous inner class for mouse motion event handling
SelfContainedPanelTest.java Lines Line 32
Instantiate SelfCustomPanel object and set background to yellow
Register anonymous-inner-class object to handle mouse motion events

18. SelfContainedPanelTest.java Lines 38-49
new MouseMotionListener() { 36
// handle mouse drag event
public void mouseDragged( MouseEvent event ) {
setTitle( "Dragging: x=" + event.getX() +
"; y=" + event.getY() ); } 43
// handle mouse move event
public void mouseMoved( MouseEvent event ) {
setTitle( "Moving: x=" + event.getX() +
"; y=" + event.getY() ); } 50
} // end anonymous inner class 52
); // end call to addMouseMotionListener 54
setSize( 300, 200 );
setVisible( true ); } 58
// execute application
public static void main( String args[] ) {
SelfContainedPanelTest application =
new SelfContainedPanelTest(); 64
application.setDefaultCloseOperation(
JFrame.EXIT_ON_CLOSE ); } 68
69 } // end class SelfContainedPanelTest
SelfContainedPanelTest.java Lines 38-49
Display String in title bar indicating x-y coordinate where mouse-motion event occurred

19. SelfContainedPanelTest.java Program Output

20. JSlider
JSlider
Enable users to select from range of integer values
Several features
Tick marks (major and minor)
Snap-to ticks
Block marks
Orientation (horizontal and vertical)

21. Fig 13.6 Horizontal JSlider Component
Tick Mark
Thumb

22. OvalPanel.java Line 18 Lines 22-28
1 // Fig. 13.7: OvalPanel.java
2 // A customized JPanel class. 3
4 // Java core packages
5 import java.awt.*; 6
7 // Java extension packages
8 import javax.swing.*; 9
10 public class OvalPanel extends JPanel {
private int diameter = 10; 12
// draw an oval of the specified diameter
public void paintComponent( Graphics g ) {
super.paintComponent( g ); 17
g.fillOval( 10, 10, diameter, diameter ); } 20
// validate and set diameter, then repaint
public void setDiameter( int newDiameter ) {
// if diameter invalid, default to 10
diameter = ( newDiameter >= 0 ? newDiameter : 10 ); 26
repaint(); } 29
// used by layout manager to determine preferred size
public Dimension getPreferredSize() {
return new Dimension( 200, 200 ); } 35
OvalPanel.java Line 18 Lines 22-28
Draw filled oval of diameter
Set diameter, then repaint

23. OvalPanel.java 36 // used by layout manager to determine minimum size
public Dimension getMinimumSize() {
return getPreferredSize(); } 41
42 } // end class OvalPanel
OvalPanel.java

24. SliderDemo.java Lines 22-23 Lines 26-27 Line 32
1 // Fig. 13.8: SliderDemo.java
2 // Using JSliders to size an oval. 3
4 // Java core packages
5 import java.awt.*;
6 import java.awt.event.*; 7
8 // Java extension packages
9 import javax.swing.*;
10 import javax.swing.event.*; 11
12 public class SliderDemo extends JFrame {
private JSlider diameterSlider;
private OvalPanel myPanel; 15
// set up GUI
public SliderDemo() {
super( "Slider Demo" ); 20
// set up OvalPanel
myPanel = new OvalPanel();
myPanel.setBackground( Color.yellow ); 24
// set up JSlider to control diameter value
diameterSlider =
new JSlider( SwingConstants.HORIZONTAL, 0, 200, 10 );
diameterSlider.setMajorTickSpacing( 10 );
diameterSlider.setPaintTicks( true ); 30
// register JSlider event listener
diameterSlider.addChangeListener( 33
SliderDemo.java Lines Lines Line 32
Instantiate OvalPanel object and set background to yellow
Instantiate horizontal JSlider object with min. value of 0, max. value of 200 and initial thumb location at 10
Register anonymous ChangeListener object to handle JSlider events

25. SliderDemo.java Lines 38-41
new ChangeListener() { 36
// handle change in slider value
public void stateChanged( ChangeEvent e ) {
myPanel.setDiameter( diameterSlider.getValue() ); } 42
} // end anonymous inner class 44
); // end call to addChangeListener 46
// attach components to content pane
Container container = getContentPane();
container.add( diameterSlider, BorderLayout.SOUTH );
container.add( myPanel, BorderLayout.CENTER ); 51
setSize( 220, 270 );
setVisible( true ); } 55
// execute application
public static void main( String args[] ) {
SliderDemo application = new SliderDemo(); 60
application.setDefaultCloseOperation(
JFrame.EXIT_ON_CLOSE ); } 64
65 } // end class SliderDemo
SliderDemo.java Lines 38-41
When user accesses JSlider, set OvalPanel’s diameter according to JSlider value

26. SliderDemo.java Program Output

27. 13.6 Windows JFrame Windows with title bar and border
Subclass of java.awt.Frame
Subclass of java.awt.Window
Heavyweight component
Three operations when user closes window
DISPOSE_ON_CLOSE
DO_NOTHING_ON_CLOSE
HIDE_ON_CLOSE

28. 13.7 Designing Programs that Execute as Applets or Applications
Java programs
Stand-alone applications
JFrame
Applets in Web browsers
Convert applet to GUI-based application

29. DrawShapes is an applet
1 // Fig. 13.9: DrawShapes.java
2 // Draw random lines, rectangles and ovals 3
4 // Java core packages
5 import java.awt.*;
6 import java.awt.event.*; 7
8 // Java extension packages
9 import javax.swing.*; 10
11 public class DrawShapes extends JApplet {
private JButton choices[];
private String names[] = { "Line", "Rectangle", "Oval" };
private JPanel buttonPanel;
private DrawPanel drawingPanel;
private int width = 300, height = 200; 17
// initialize applet; set up GUI
public void init() {
// set up DrawPanel
drawingPanel = new DrawPanel( width, height ); 23
// create array of buttons
choices = new JButton[ names.length ]; 26
// set up panel for buttons
buttonPanel = new JPanel();
buttonPanel.setLayout(
new GridLayout( 1, choices.length ) ); 31
// set up buttons and register their listeners
ButtonHandler handler = new ButtonHandler(); 34
DrawShapes.java Line 11
DrawShapes is an applet

30. DrawShapes.java Line 60 Lines 62 Lines 65-68
for ( int count = 0; count < choices.length; count++ ) {
choices[ count ] = new JButton( names[ count ] );
buttonPanel.add( choices[ count ] );
choices[ count ].addActionListener( handler ); } 40
// attach components to content pane
Container container = getContentPane();
container.add( buttonPanel, BorderLayout.NORTH );
container.add( drawingPanel, BorderLayout.CENTER ); } 46
// enables application to specify width of drawing area
public void setWidth( int newWidth ) {
width = ( newWidth >= 0 ? newWidth : 300 ); } 52
// enables application to specify height of drawing area
public void setHeight( int newHeight ) {
height = ( newHeight >= 0 ? newHeight : 200 ); } 58
// execute applet as an application
public static void main( String args[] ) {
int width, height; 63
// check for command-line arguments
if ( args.length != 2 ) {
width = 300;
height = 200; }
DrawShapes.java Line 60 Lines 62 Lines 65-68
DrawShapes is stand-alone application as well
Specify application-window size
Determine initial application-window size

31. DrawShapes.java Lines 69-72 Lines 75-76 Lines 78-79 Lines 82-88
else {
width = Integer.parseInt( args[ 0 ] );
height = Integer.parseInt( args[ 1 ] ); } 73
// create window in which applet will execute
JFrame applicationWindow =
new JFrame( "An applet running as an application" ); 77
applicationWindow.setDefaultCloseOperation(
JFrame.EXIT_ON_CLOSE ); 80
// create one applet instance
DrawShapes appletObject = new DrawShapes();
appletObject.setWidth( width );
appletObject.setHeight( height ); 85
// call applet's init and start methods
appletObject.init();
appletObject.start(); 89
// attach applet to center of window
applicationWindow.getContentPane().add( appletObject ); 92
// set the window's size
applicationWindow.setSize( width, height ); 95
// showing the window causes all GUI components
// attached to the window to be painted
applicationWindow.setVisible( true ); }
100
// private inner class to handle button events
private class ButtonHandler implements ActionListener {
103
Use command-line arguments to specify window width and height
DrawShapes.java Lines Lines Lines Lines 82-88
Instantiate JFrame to run as stand-alone application
Allow for window termination
Instantiate and initialize applet if stand-alone application

32. 104 // determine button user pressed and set drawing area's
// current choice
public void actionPerformed( ActionEvent event ) {
for ( int count = 0; count < choices.length; count++ )
109
if ( event.getSource() == choices[ count ] ) {
drawingPanel.setCurrentChoice( count );
break; } }
115
} // end private inner class ButtonHandler
117
118 } // end class DrawShapes
119
120 // subclass of JPanel to allow drawing in a separate area
121 class DrawPanel extends JPanel {
private int currentChoice = -1; // don't draw first time
private int width = 100, height = 100;
124
// initialize width and height of DrawPanel
public DrawPanel( int newWidth, int newHeight ) {
width = ( newWidth >= 0 ? newWidth : 100 );
height = ( newHeight >= 0 ? newHeight : 100 ); }
131
// draw line, rectangle or oval based on user's choice
public void paintComponent( Graphics g ) {
super.paintComponent( g );
136
DrawShapes.java

33. DrawShapes.java 136 137 switch( currentChoice ) { 138 139 case 0:
g.drawLine( randomX(), randomY(),
randomX(), randomY() );
break;
143
case 1:
g.drawRect( randomX(), randomY(),
randomX(), randomY() );
break;
148
case 2:
g.drawOval( randomX(), randomY(),
randomX(), randomY() );
break; }
154
} // end method paintComponent
156
// specify current shape choice and repaint
public void setCurrentChoice( int choice ) {
currentChoice = choice;
repaint(); }
163
// pick random x coordinate
private int randomX() {
return ( int ) ( Math.random() * width ); }
169
DrawShapes.java

34. DrawShapes.java Program Output
// pick random y coordinate
private int randomY() {
return ( int ) ( Math.random() * height ); }
175
176 } // end class DrawPanel
DrawShapes.java Program Output

35. 13.8 Using Menus with Frames
Allows for performing actions with cluttering GUI
Contained by menu bar
JMenuBar
Comprised of menu items
JMenuItem

36. MenuTest.java Line 27 Line 31
1 // Fig : MenuTest.java
2 // Demonstrating menus 3
4 // Java core packages
5 import java.awt.*;
6 import java.awt.event.*; 7
8 // Java extension packages
9 import javax.swing.*; 10
11 public class MenuTest extends JFrame {
private Color colorValues[] =
{ Color.black, Color.blue, Color.red, Color.green }; 14
private JRadioButtonMenuItem colorItems[], fonts[];
private JCheckBoxMenuItem styleItems[];
private JLabel displayLabel;
private ButtonGroup fontGroup, colorGroup;
private int style; 20
// set up GUI
public MenuTest() {
super( "Using JMenus" ); 25
// set up File menu and its menu items
JMenu fileMenu = new JMenu( "File" );
fileMenu.setMnemonic( 'F' ); 29
// set up About... menu item
JMenuItem aboutItem = new JMenuItem( "About..." );
aboutItem.setMnemonic( 'A' ); 33
aboutItem.addActionListener( 35
MenuTest.java Line 27 Line 31
Instantiate File JMenu
Instantiate About… JMenuItem to be placed in fileMenu

37. MenuTest.java Lines 40-45 Line 54 Lines 63-66
// anonymous inner class to handle menu item event
new ActionListener() { 38
// display message dialog when user selects About...
public void actionPerformed( ActionEvent event ) {
JOptionPane.showMessageDialog( MenuTest.this,
"This is an example\nof using menus",
"About", JOptionPane.PLAIN_MESSAGE ); } 46
} // end anonymous inner class 48
); // end call to addActionListener 50
fileMenu.add( aboutItem ); 52
// set up Exit menu item
JMenuItem exitItem = new JMenuItem( "Exit" );
exitItem.setMnemonic( 'x' ); 56
exitItem.addActionListener( 58
// anonymous inner class to handle exitItem event
new ActionListener() { 61
// terminate application when user clicks exitItem
public void actionPerformed( ActionEvent event ) {
System.exit( 0 ); } 67
} // end anonymous inner class 69
); // end call to addActionListener
MenuTest.java Lines Line 54 Lines 63-66
When user selects About… JMenuItem, display message dialog with appropriate text
Instantiate Exit JMenuItem to be placed in fileMenu
When user selects Exit JMenuItem, exit system

38. MenuTest.java Line 75 Line 80 Line 86 Lines 89-9071
fileMenu.add( exitItem ); 73
// create menu bar and attach it to MenuTest window
JMenuBar bar = new JMenuBar();
setJMenuBar( bar );
bar.add( fileMenu ); 78
// create Format menu, its submenus and menu items
JMenu formatMenu = new JMenu( "Format" );
formatMenu.setMnemonic( 'r' ); 82
// create Color submenu
String colors[] = { "Black", "Blue", "Red", "Green" }; 85
JMenu colorMenu = new JMenu( "Color" );
colorMenu.setMnemonic( 'C' ); 88
colorItems = new JRadioButtonMenuItem[ colors.length ];
colorGroup = new ButtonGroup();
ItemHandler itemHandler = new ItemHandler(); 92
// create color radio button menu items
for ( int count = 0; count < colors.length; count++ ) {
colorItems[ count ] =
new JRadioButtonMenuItem( colors[ count ] ); 97
colorMenu.add( colorItems[ count ] );
colorGroup.add( colorItems[ count ] );
100
colorItems[ count ].addActionListener( itemHandler ); }
103
// select first Color menu item
colorItems[ 0 ].setSelected( true );
MenuTest.java Line 75 Line 80 Line 86 Lines 89-90
Instantiate JMenuBar to contain JMenus
Instantiate Format JMenu
Instantiate Color JMenu (submenu of Format JMenu)
Instantiate JRadioButtonMenuItems for Color JMenu and ensure that only one menu item is selected at a time

39. MenuTest.java Line 109 Line 114 Lines 117-118
106
// add format menu to menu bar
formatMenu.add( colorMenu );
formatMenu.addSeparator();
110
// create Font submenu
String fontNames[] = { "Serif", "Monospaced", "SansSerif" };
113
JMenu fontMenu = new JMenu( "Font" );
fontMenu.setMnemonic( 'n' );
116
fonts = new JRadioButtonMenuItem[ fontNames.length ];
fontGroup = new ButtonGroup();
119
// create Font radio button menu items
for ( int count = 0; count < fonts.length; count++ ) {
fonts[ count ] =
new JRadioButtonMenuItem( fontNames[ count ] );
124
fontMenu.add( fonts[ count ] );
fontGroup.add( fonts[ count ] );
127
fonts[ count ].addActionListener( itemHandler ); }
130
// select first Font menu item
fonts[ 0 ].setSelected( true );
133
fontMenu.addSeparator();
135
// set up style menu items
String styleNames[] = { "Bold", "Italic" };
138
styleItems = new JCheckBoxMenuItem[ styleNames.length ];
StyleHandler styleHandler = new StyleHandler();
Separator places line between JMenuItems
MenuTest.java Line 109 Line 114 Lines
Instantiate Font JMenu (submenu of Format JMenu)
Instantiate JRadioButtonMenuItems for Font JMenu and ensure that only one menu item is selected at a time

40. MenuTest.java 141 142 // create style checkbox menu items
for ( int count = 0; count < styleNames.length; count++ ) {
styleItems[ count ] =
new JCheckBoxMenuItem( styleNames[ count ] );
146
fontMenu.add( styleItems[ count ] );
148
styleItems[ count ].addItemListener( styleHandler ); }
151
// put Font menu in Format menu
formatMenu.add( fontMenu );
154
// add Format menu to menu bar
bar.add( formatMenu );
157
// set up label to display text
displayLabel = new JLabel(
"Sample Text", SwingConstants.CENTER );
displayLabel.setForeground( colorValues[ 0 ] );
displayLabel.setFont(
new Font( "TimesRoman", Font.PLAIN, 72 ) );
164
getContentPane().setBackground( Color.cyan );
getContentPane().add( displayLabel, BorderLayout.CENTER );
167
setSize( 500, 200 );
setVisible( true );
170
} // end constructor
172
MenuTest.java

41. MenuTest.java Line 186 Lines 189-203 Lines 192 and 200-201
// execute application
public static void main( String args[] ) {
MenuTest application = new MenuTest();
177
application.setDefaultCloseOperation(
JFrame.EXIT_ON_CLOSE ); }
181
// inner class to handle action events from menu items
private class ItemHandler implements ActionListener {
184
// process color and font selections
public void actionPerformed( ActionEvent event ) {
// process color selection
for ( int count = 0; count < colorItems.length; count++ )
190
if ( colorItems[ count ].isSelected() ) {
displayLabel.setForeground( colorValues[ count ] );
break; }
195
// process font selection
for ( int count = 0; count < fonts.length; count++ )
198
if ( event.getSource() == fonts[ count ] ) {
displayLabel.setFont( new Font(
fonts[ count ].getText(), style, 72 ) );
break; }
204
repaint(); }
207
MenuTest.java Line 186 Lines Lines 192 and
Invoked when user selects JMenuItem
Determine which font or color menu generated event
Set font or color of JLabel, respectively

42. MenuTest.java Line 214 Lines 219-224
Invoked when user selects JCheckBoxMenuItem
} // end class ItemHandler
209
// inner class to handle item events from check box menu items
private class StyleHandler implements ItemListener {
212
// process font style selections
public void itemStateChanged( ItemEvent e ) {
style = 0;
217
// check for bold selection
if ( styleItems[ 0 ].isSelected() )
style += Font.BOLD;
221
// check for italic selection
if ( styleItems[ 1 ].isSelected() )
style += Font.ITALIC;
225
displayLabel.setFont( new Font(
displayLabel.getFont().getName(), style, 72 ) );
228
repaint(); }
231
} // end class StyleHandler
233
234 } // end class MenuTest
MenuTest.java Line 214 Lines
Determine new font style

43. MenuTest.java Program Output

44. Context-sensitive popup menus
Using JPopupMenus
Context-sensitive popup menus
JPopupMenu
Menu generated depending on which component is accessed

45. Instantiate JPopupMenu object
1 // Fig : PopupTest.java
2 // Demonstrating JPopupMenus 3
4 // Java core packages
5 import java.awt.*;
6 import java.awt.event.*; 7
8 // Java extension packages
9 import javax.swing.*; 10
11 public class PopupTest extends JFrame { 12
private JRadioButtonMenuItem items[];
private Color colorValues[] =
{ Color.blue, Color.yellow, Color.red }; 16
private JPopupMenu popupMenu; 18
// set up GUI
public PopupTest() {
super( "Using JPopupMenus" ); 23
ItemHandler handler = new ItemHandler();
String colors[] = { "Blue", "Yellow", "Red" }; 26
// set up popup menu and its items
ButtonGroup colorGroup = new ButtonGroup();
popupMenu = new JPopupMenu();
items = new JRadioButtonMenuItem[ 3 ]; 31
PopupTest.java Line 29
Instantiate JPopupMenu object

46. PopupTest.java Lines 34-42 Lines 56 and 62
// construct each menu item and add to popup menu; also
// enable event handling for each menu item
for ( int count = 0; count < items.length; count++ ) {
items[ count ] =
new JRadioButtonMenuItem( colors[ count ] ); 37
popupMenu.add( items[ count ] );
colorGroup.add( items[ count ] ); 40
items[ count ].addActionListener( handler ); } 43
getContentPane().setBackground( Color.white ); 45
// define a MouseListener for the window that displays
// a JPopupMenu when the popup trigger event occurs
addMouseListener( 49
// anonymous inner class to handle mouse events
new MouseAdapter() { 52
// handle mouse press event
public void mousePressed( MouseEvent event ) {
checkForTriggerEvent( event ); } 58
// handle mouse release event
public void mouseReleased( MouseEvent event ) {
checkForTriggerEvent( event ); } 64
PopupTest.java Lines Lines 56 and 62
Create JRadioButtonMenuItem objects to add to JPopupMenu
Determine whether popup-trigger event occurred when user presses or releases mouse button

47. PopupTest.java Lines 68-70 Line 94
// determine whether event should trigger popup menu
private void checkForTriggerEvent( MouseEvent event ) {
if ( event.isPopupTrigger() )
popupMenu.show( event.getComponent(),
event.getX(), event.getY() ); } 72
} // end anonymous inner clas 74
); // end call to addMouseListener 76
setSize( 300, 200 );
setVisible( true ); } 80
// execute application
public static void main( String args[] ) {
PopupTest application = new PopupTest(); 85
application.setDefaultCloseOperation(
JFrame.EXIT_ON_CLOSE ); } 89
// private inner class to handle menu item events
private class ItemHandler implements ActionListener { 92
// process menu item selections
public void actionPerformed( ActionEvent event ) {
PopupTest.java Lines Line 94
Show JPopupMenu if popup-trigger occurred
Invoked when user selects JRadioButtonMenuItem

48. PopupTest.java Lines 97-103 Program Output
// determine which menu item was selected
for ( int i = 0; i < items.length; i++ )
if ( event.getSource() == items[ i ] ) {
getContentPane().setBackground(
colorValues[ i ] );
repaint();
return; } }
105
} // end private inner class ItemHandler
107
108 } // end class PopupTest
PopupTest.java Lines Program Output
Determine which JRadioButtonMenuItem was selected, then set window background color

49. 13.10 Pluggable Look-and-Feel
Change look-and-feel dynamically
e.g., Microsoft Windows look-and-feel to Motif look-and-feel
Flexible

50. LookAndFeelDemo.java Line 14
1 // Fig : LookAndFeelDemo.java
2 // Changing the look and feel. 3
4 // Java core packages
5 import java.awt.*;
6 import java.awt.event.*; 7
8 // Java extension packages
9 import javax.swing.*; 10
11 public class LookAndFeelDemo extends JFrame { 12
private String strings[] = { "Metal", "Motif", "Windows" };
private UIManager.LookAndFeelInfo looks[];
private JRadioButton radio[];
private ButtonGroup group;
private JButton button;
private JLabel label;
private JComboBox comboBox; 20
// set up GUI
public LookAndFeelDemo() {
super( "Look and Feel Demo" ); 25
Container container = getContentPane(); 27
// set up panel for NORTH of BorderLayout
JPanel northPanel = new JPanel();
northPanel.setLayout( new GridLayout( 3, 1, 0, 5 ) ); 31
// set up label for NORTH panel
label = new JLabel( "This is a Metal look-and-feel",
SwingConstants.CENTER );
northPanel.add( label );
LookAndFeelDemo.java Line 14
Hold installed look-and-feel information

51. LookAndFeelDemo.java 36 37 // set up button for NORTH panel
button = new JButton( "JButton" );
northPanel.add( button ); 40
// set up combo box for NORTH panel
comboBox = new JComboBox( strings );
northPanel.add( comboBox ); 44
// attach NORTH panel to content pane
container.add( northPanel, BorderLayout.NORTH ); 47
// create array for radio buttons
radio = new JRadioButton[ strings.length ]; 50
// set up panel for SOUTH of BorderLayout
JPanel southPanel = new JPanel();
southPanel.setLayout(
new GridLayout( 1, radio.length ) ); 55
// set up radio buttons for SOUTH panel
group = new ButtonGroup();
ItemHandler handler = new ItemHandler(); 59
for ( int count = 0; count < radio.length; count++ ) {
radio[ count ] = new JRadioButton( strings[ count ] );
radio[ count ].addItemListener( handler );
group.add( radio[ count ] );
southPanel.add( radio[ count ] ); } 66
// attach SOUTH panel to content pane
container.add( southPanel, BorderLayout.SOUTH ); 69
LookAndFeelDemo.java

52. LookAndFeelDemo.java Lines 84-86
// get installed look-and-feel information
looks = UIManager.getInstalledLookAndFeels(); 72
setSize( 300, 200 );
setVisible( true ); 75
radio[ 0 ].setSelected( true ); } 78
// use UIManager to change look-and-feel of GUI
private void changeTheLookAndFeel( int value ) {
// change look and feel
try {
UIManager.setLookAndFeel(
looks[ value ].getClassName() );
SwingUtilities.updateComponentTreeUI( this ); } 88
// process problems changing look and feel
catch ( Exception exception ) {
exception.printStackTrace(); } } 94
// execute application
public static void main( String args[] ) {
LookAndFeelDemo application = new LookAndFeelDemo(); 99
application.setDefaultCloseOperation(
JFrame.EXIT_ON_CLOSE ); }
103
LookAndFeelDemo.java Lines 84-86
Change look-and-feel

53. 104 // private inner class to handle radio button events
private class ItemHandler implements ItemListener {
106
// process user's look-and-feel selection
public void itemStateChanged( ItemEvent event ) {
for ( int count = 0; count < radio.length; count++ )
111
if ( radio[ count ].isSelected() ) {
label.setText( "This is a " +
strings[ count ] + " look-and-feel" );
comboBox.setSelectedIndex( count );
116
changeTheLookAndFeel( count ); } }
120
} // end private inner class ItemHandler
122
123 } // end class LookAndFeelDemo
LookAndFeelDemo.java

54. 13.11 Using JDesktopPane and JInternalFrame
Multiple document interface
Main (parent) window
Child windows
Switch freely among documents

55. DesktopTest.java Line 12 Line 34
1 // Fig : DesktopTest.java
2 // Demonstrating JDesktopPane. 3
4 // Java core packages
5 import java.awt.*;
6 import java.awt.event.*; 7
8 // Java extension packages
9 import javax.swing.*; 10
11 public class DesktopTest extends JFrame {
private JDesktopPane theDesktop; 13
// set up GUI
public DesktopTest() {
super( "Using a JDesktopPane" ); 18
// create menu bar, menu and menu item
JMenuBar bar = new JMenuBar();
JMenu addMenu = new JMenu( "Add" );
JMenuItem newFrame = new JMenuItem( "Internal Frame" ); 23
addMenu.add( newFrame );
bar.add( addMenu ); 26
setJMenuBar( bar ); 28
// set up desktop
theDesktop = new JDesktopPane();
getContentPane().add( theDesktop ); 32
// set up listener for newFrame menu item
newFrame.addActionListener( 35
DesktopTest.java Line 12 Line 34
Manages JInternalFrame child windows displayed in JDesktopPane
Handle event when user selects JMenuItem

56. DesktopTest.java Line 40 Lines 43-44 Lines 48-49 Line 52
// anonymous inner class to handle menu item event
new ActionListener() { 38
// display new internal window
public void actionPerformed( ActionEvent event ) { 41
// create internal frame
JInternalFrame frame = new JInternalFrame(
"Internal Frame", true, true, true, true ); 45
// attach panel to internal frame content pane
Container container = frame.getContentPane();
MyJPanel panel = new MyJPanel();
container.add( panel, BorderLayout.CENTER ); 50
// set size internal frame to size of its contents
frame.pack(); 53
// attach internal frame to desktop and show it
theDesktop.add( frame );
frame.setVisible( true ); } 58
} // end anonymous inner class 60
); // end call to addActionListener 62
setSize( 600, 440 );
setVisible( true ); 65
} // end constructor 67
Invoked when user selects JMenuItem
DesktopTest.java Line 40 Lines Lines Line 52
Create JInternalFrame
JPanels can be added to JInternalFrames
Use preferred size for window

57. DesktopTest.java 68 // execute application
public static void main( String args[] ) {
DesktopTest application = new DesktopTest(); 72
application.setDefaultCloseOperation(
JFrame.EXIT_ON_CLOSE ); } 76
77 } // end class DesktopTest 78
79 // class to display an ImageIcon on a panel
80 class MyJPanel extends JPanel {
private ImageIcon imageIcon; 82
// load image
public MyJPanel() {
imageIcon = new ImageIcon( "jhtp4.png" ); } 88
// display imageIcon on panel
public void paintComponent( Graphics g ) {
// call superclass paintComponent method
super.paintComponent( g ); 94
// display icon
imageIcon.paintIcon( this, g, 0, 0 ); } 98
DesktopTest.java

58. DesktopTest.java Program Output
// return image dimensions
public Dimension getPreferredSize() {
return new Dimension( imageIcon.getIconWidth(),
imageIcon.getIconHeight() ); }
105
106 } // end class MyJPanel
DesktopTest.java Program Output
Internal Frames
Minimize
Maximize
Close
Minimized internal frame
Position the mouse over any corner of a child
window to resize the window (if resizing is allowed).

59. DesktopTest.java Program Output
Maximized Internal Frame
DesktopTest.java Program Output

60. 13.12 Layout Managers Layout Managers BoxLayout CardLayout
GridBagLayout

61. Fig. 13.14 Additional Layout Managers

62. 13.13 BoxLayout Layout Manager
Arranges GUI components
Horizontally along x-axis
Vertically along y-axis

63. BoxLayoutDemo.java Lines 23-28 Lines 31-32
1 // Fig : BoxLayoutDemo.java
2 // Demonstrating BoxLayout. 3
4 // Java core packages
5 import java.awt.*;
6 import java.awt.event.*; 7
8 // Java extension packages
9 import javax.swing.*; 10
11 public class BoxLayoutDemo extends JFrame { 12
// set up GUI
public BoxLayoutDemo() {
super( "Demostrating BoxLayout" );
final int SIZE = 3; 18
Container container = getContentPane();
container.setLayout( new BorderLayout( 30, 30 ) ); 21
// create Box containers with BoxLayout
Box boxes[] = new Box[ 4 ]; 24
boxes[ 0 ] = Box.createHorizontalBox();
boxes[ 1 ] = Box.createVerticalBox();
boxes[ 2 ] = Box.createHorizontalBox();
boxes[ 3 ] = Box.createVerticalBox(); 29
// add buttons to boxes[ 0 ]
for ( int count = 0; count < SIZE; count++ )
boxes[ 0 ].add( new JButton( "boxes[0]: " + count ) ); 33
BoxLayoutDemo.java Lines Lines 31-32
Define and populate array of Box containers
Add three JButtons to horizontal Box

64. Add three JButtons to vertical Box
// create strut and add buttons to boxes[ 1 ]
for ( int count = 0; count < SIZE; count++ ) {
boxes[ 1 ].add( Box.createVerticalStrut( 25 ) );
boxes[ 1 ].add( new JButton( "boxes[1]: " + count ) ); } 39
// create horizontal glue and add buttons to boxes[ 2 ]
for ( int count = 0; count < SIZE; count++ ) {
boxes[ 2 ].add( Box.createHorizontalGlue() );
boxes[ 2 ].add( new JButton( "boxes[2]: " + count ) ); } 45
// create rigid area and add buttons to boxes[ 3 ]
for ( int count = 0; count < SIZE; count++ ) {
boxes[ 3 ].add(
Box.createRigidArea( new Dimension( 12, 8 ) ) );
boxes[ 3 ].add( new JButton( "boxes[3]: " + count ) ); } 52
// create vertical glue and add buttons to panel
JPanel panel = new JPanel();
panel.setLayout(
new BoxLayout( panel, BoxLayout.Y_AXIS ) ); 57
for ( int count = 0; count < SIZE; count++ ) {
panel.add( Box.createGlue() );
panel.add( new JButton( "panel: " + count ) ); } 62
// place panels on frame
container.add( boxes[ 0 ], BorderLayout.NORTH );
container.add( boxes[ 1 ], BorderLayout.EAST );
container.add( boxes[ 2 ], BorderLayout.SOUTH );
container.add( boxes[ 3 ], BorderLayout.WEST );
container.add( panel, BorderLayout.CENTER );
Strut guarantees space between components
BoxLayoutDemo.java Lines Line 36 Lines Line 42 Lines Line 49
Add three JButtons to horizontal Box
Glue guarantees expandable space between components
Add three JButtons to vertical Box
Rigid area guarantees fixed component size

65. BoxLayoutDemo.java Program Output69
setSize( 350, 300 );
setVisible( true ); 72
} // end constructor 74
// execute application
public static void main( String args[] ) {
BoxLayoutDemo application = new BoxLayoutDemo(); 79
application.setDefaultCloseOperation(
JFrame.EXIT_ON_CLOSE ); } 83
84 } // end class BoxLayoutDemo
BoxLayoutDemo.java Program Output

66. BoxLayoutDemo.java Program Output

67. 13.14 CardLayout Layout Manager
Arranges components in a “deck” of cards
Only top “card” is visible
Any card can be placed on top of deck
Each card can use its own layout manager

68. CardDeck.java Lines 16-17 Lines 28-29
1 // Fig : CardDeck.java
2 // Demonstrating CardLayout. 3
4 // Java core packages
5 import java.awt.*;
6 import java.awt.event.*; 7
8 // Java extension packages
9 import javax.swing.*; 10
11 public class CardDeck extends JFrame implements ActionListener { 12
private CardLayout cardManager;
private JPanel deck;
private JButton controls[];
private String names[] = { "First card", "Next card",
"Previous card", "Last card" }; 18
// set up GUI
public CardDeck() {
super( "CardLayout " ); 23
Container container = getContentPane(); 25
// create the JPanel with CardLayout
deck = new JPanel();
cardManager = new CardLayout();
deck.setLayout( cardManager ); 30
CardDeck.java Lines Lines 28-29
Card names
Set CardLayout as layout manager for JPanel deck

69. CardDeck.java Lines 32-36 Lines 39-44 Lines 47-55 Lines 58-66
// set up card1 and add it to JPanel deck
JLabel label1 =
new JLabel( "card one", SwingConstants.CENTER );
JPanel card1 = new JPanel();
card1.add( label1 );
deck.add( card1, label1.getText() ); // add card to deck 37
// set up card2 and add it to JPanel deck
JLabel label2 =
new JLabel( "card two", SwingConstants.CENTER );
JPanel card2 = new JPanel();
card2.setBackground( Color.yellow );
card2.add( label2 );
deck.add( card2, label2.getText() ); // add card to deck 45
// set up card3 and add it to JPanel deck
JLabel label3 = new JLabel( "card three" );
JPanel card3 = new JPanel();
card3.setLayout( new BorderLayout() );
card3.add( new JButton( "North" ), BorderLayout.NORTH );
card3.add( new JButton( "West" ), BorderLayout.WEST );
card3.add( new JButton( "East" ), BorderLayout.EAST );
card3.add( new JButton( "South" ), BorderLayout.SOUTH );
card3.add( label3, BorderLayout.CENTER );
deck.add( card3, label3.getText() ); // add card to deck 56
// create and layout buttons that will control deck
JPanel buttons = new JPanel();
buttons.setLayout( new GridLayout( 2, 2 ) );
controls = new JButton[ names.length ]; 61
for ( int count = 0; count < controls.length; count++ ) {
controls[ count ] = new JButton( names[ count ] );
controls[ count ].addActionListener( this );
buttons.add( controls[ count ] );
Create first card as JPanel and add to deck
CardDeck.java Lines Lines Lines Lines 58-66
Create second card as JPanel with yellow background and add to deck
Create third card as JPanel with BorderLayout and add to deck
Create fourth card as JPanel with GridLayout and add to deck

70. Switch card in deck, depending on JButton pressed by user} 67
// add JPanel deck and JPanel buttons to the applet
container.add( buttons, BorderLayout.WEST );
container.add( deck, BorderLayout.EAST ); 71
setSize( 450, 200 );
setVisible( true ); 74
} // end constructor 76
// handle button events by switching cards
public void actionPerformed( ActionEvent event ) {
// show first card
if ( event.getSource() == controls[ 0 ] )
cardManager.first( deck ); 83
// show next card
else if ( event.getSource() == controls[ 1 ] )
cardManager.next( deck ); 87
// show previous card
else if ( event.getSource() == controls[ 2 ] )
cardManager.previous( deck ); 91
// show last card
else if ( event.getSource() == controls[ 3 ] )
cardManager.last( deck ); } 96
CardDeck.java Lines 81-94
Switch card in deck, depending on JButton pressed by user

71. CardDeck.java Program Output
// execute application
public static void main( String args[] ) {
CardDeck cardDeckDemo = new CardDeck();
101
cardDeckDemo.setDefaultCloseOperation(
JFrame.EXIT_ON_CLOSE ); }
105
106 } // end class CardDeck
CardDeck.java Program Output

72. 13.15 GridBagLayout Layout Manager.
Flexible GridBagLayout
Components can vary in size
Components can occupy multiple rows and columns
Components can be added in any order
Uses GridBagConstraints
Specifies how component is placed in GridBagLayout

73. Fig. 13.17 Designing a GUI that will use GridBagLayout.

74. Fig. 13.18 GridBagConstraints instance variables.

75. Fig. 13.19 GridBagLayout with the weights set to zero.

76. GridBagDemo.java Lines 22-23 Line 26
1 // Fig : GridBagDemo.java
2 // Demonstrating GridBagLayout. 3
4 // Java core packages
5 import java.awt.*;
6 import java.awt.event.*; 7
8 // Java extension packages
9 import javax.swing.*; 10
11 public class GridBagDemo extends JFrame {
private Container container;
private GridBagLayout layout;
private GridBagConstraints constraints; 15
// set up GUI
public GridBagDemo() {
super( "GridBagLayout" ); 20
container = getContentPane();
layout = new GridBagLayout();
container.setLayout( layout ); 24
// instantiate gridbag constraints
constraints = new GridBagConstraints(); 27
// create GUI components
JTextArea textArea1 = new JTextArea( "TextArea1", 5, 10 );
JTextArea textArea2 = new JTextArea( "TextArea2", 2, 2 ); 31
String names[] = { "Iron", "Steel", "Brass" };
JComboBox comboBox = new JComboBox( names ); 34
GridBagDemo.java Lines Line 26
Set GridBagLayout as layout manager
Used to determine component location and size in grid

77. GridBagDemo.java Line 43 Line 44 Line 48 Line 49 Lines 57-60
If user resizes Container, first JTextArea is filled entire allocated area in grid
JTextField textField = new JTextField( "TextField" );
JButton button1 = new JButton( "Button 1" );
JButton button2 = new JButton( "Button 2" );
JButton button3 = new JButton( "Button 3" ); 39
// textArea1
// weightx and weighty are both 0: the default
// anchor for all components is CENTER: the default
constraints.fill = GridBagConstraints.BOTH;
addComponent( textArea1, 0, 0, 1, 3 ); 45
// button1
// weightx and weighty are both 0: the default
constraints.fill = GridBagConstraints.HORIZONTAL;
addComponent( button1, 0, 1, 2, 1 ); 50
// comboBox
// weightx and weighty are both 0: the default
// fill is HORIZONTAL
addComponent( comboBox, 2, 1, 2, 1 ); 55
// button2
constraints.weightx = 1000; // can grow wider
constraints.weighty = 1; // can grow taller
constraints.fill = GridBagConstraints.BOTH;
addComponent( button2, 1, 1, 1, 1 ); 61
// button3
// fill is BOTH
constraints.weightx = 0;
constraints.weighty = 0;
addComponent( button3, 1, 2, 1, 1 ); 67
GridBagDemo.java Line 43 Line 44 Line 48 Line 49 Lines 57-60
First JTextArea spans one row and three columns
If user resizes Container, first JButton fills horizontally in grid
First JButton spans two rows and one column
If user resizes Container, second JButton fills extra space

78. GridBagDemo.java 68 // textField
// weightx and weighty are both 0, fill is BOTH
addComponent( textField, 3, 0, 2, 1 ); 71
// textArea2
// weightx and weighty are both 0, fill is BOTH
addComponent( textArea2, 3, 2, 1, 1 ); 75
setSize( 300, 150 );
setVisible( true ); } 79
// method to set constraints on
private void addComponent( Component component,
int row, int column, int width, int height ) {
// set gridx and gridy
constraints.gridx = column;
constraints.gridy = row; 87
// set gridwidth and gridheight
constraints.gridwidth = width;
constraints.gridheight = height; 91
// set constraints and add component
layout.setConstraints( component, constraints );
container.add( component ); } 96
GridBagDemo.java

79. GridBagDemo.java Program Output
// execute application
public static void main( String args[] ) {
GridBagDemo application = new GridBagDemo();
101
application.setDefaultCloseOperation(
JFrame.EXIT_ON_CLOSE ); }
105
106 } // end class GridBagDemo
GridBagDemo.java Program Output

80. GridBagDemo.java Program Output

81. 13.16 GridBagConstraints Constants RELATIVE and REMAINDER
Used in place of variables gridx and gridy
RELATIVE
Specifies next-to-last component placement in row or column
Component should be placed next to one previously added
REMAINDER
Specifies component as last component in row or column

82. GridBagDemo2.java Lines 22-23 Line 26
1 // Fig : GridBagDemo2.java
2 // Demonstrating GridBagLayout constants. 3
4 // Java core packages
5 import java.awt.*;
6 import java.awt.event.*; 7
8 // Java extension packages
9 import javax.swing.*; 10
11 public class GridBagDemo2 extends JFrame {
private GridBagLayout layout;
private GridBagConstraints constraints;
private Container container; 15
// set up GUI
public GridBagDemo2() {
super( "GridBagLayout" ); 20
container = getContentPane();
layout = new GridBagLayout();
container.setLayout( layout ); 24
// instantiate gridbag constraints
constraints = new GridBagConstraints(); 27
// create GUI components
String metals[] = { "Copper", "Aluminum", "Silver" };
JComboBox comboBox = new JComboBox( metals ); 31
JTextField textField = new JTextField( "TextField" ); 33
String fonts[] = { "Serif", "Monospaced" };
JList list = new JList( fonts );
GridBagDemo2.java Lines Line 26
Set GridBagLayout as layout manager
Used to determine component location and size in grid

83. Specify textField as last (only) component in first row36
String names[] =
{ "zero", "one", "two", "three", "four" };
JButton buttons[] = new JButton[ names.length ]; 40
for ( int count = 0; count < buttons.length; count++ )
buttons[ count ] = new JButton( names[ count ] ); 43
// define GUI component constraints
// textField
constraints.weightx = 1;
constraints.weighty = 1;
constraints.fill = GridBagConstraints.BOTH;
constraints.gridwidth = GridBagConstraints.REMAINDER;
addComponent( textField ); 51
// buttons[0] -- weightx and weighty are 1: fill is BOTH
constraints.gridwidth = 1;
addComponent( buttons[ 0 ] ); 55
// buttons[1] -- weightx and weighty are 1: fill is BOTH
constraints.gridwidth = GridBagConstraints.RELATIVE;
addComponent( buttons[ 1 ] ); 59
// buttons[2] -- weightx and weighty are 1: fill is BOTH
constraints.gridwidth = GridBagConstraints.REMAINDER;
addComponent( buttons[ 2 ] ); 63
// comboBox -- weightx is 1: fill is BOTH
constraints.weighty = 0;
constraints.gridwidth = GridBagConstraints.REMAINDER;
addComponent( comboBox ); 68
GridBagDemo2.java Line 49 Lines Lines Lines Lines 65-67
Specify textField as last (only) component in first row
Place button[0] as first component in second row
Place button[1] right next to button[0]
Place button[2] right next to button[1]
Specify comboBox as last (only) component in third row

84. GridBagDemo2.java Lines 70-72 Lines 75-76 Lines 79-80
Specify buttons[3] as last (only) component in fourth row
// buttons[3] -- weightx is 1: fill is BOTH
constraints.weighty = 1;
constraints.gridwidth = GridBagConstraints.REMAINDER;
addComponent( buttons[ 3 ] ); 73
// buttons[4] -- weightx and weighty are 1: fill is BOTH
constraints.gridwidth = GridBagConstraints.RELATIVE;
addComponent( buttons[ 4 ] ); 77
// list -- weightx and weighty are 1: fill is BOTH
constraints.gridwidth = GridBagConstraints.REMAINDER;
addComponent( list ); 81
setSize( 300, 200 );
setVisible( true ); 84
} // end constructor 86
// addComponent is programmer-defined
private void addComponent( Component component ) {
layout.setConstraints( component, constraints );
container.add( component ); // add component } 93
// execute application
public static void main( String args[] ) {
GridBagDemo2 application = new GridBagDemo2(); 98
application.setDefaultCloseOperation(
JFrame.EXIT_ON_CLOSE ); }
102
103 } // end class GridBagDemo2
GridBagDemo2.java Lines Lines Lines 79-80
Place button[4] as first component in fifth row
Specify list as last component in fifth row

85. GridbagDemo2.java Program Output

86. Model-View-Controller
(Optional Case Study) Thinking About Objects: Model-View-Controller
Model-View-Controller
Architectural pattern for building systems
Divide system responsibilities into three parts
Model
Contains all program data and logic
View
Visual representation of model
Controller
Defines system behavior by sending user input to model
Step by step
User uses controller to change data in model
Model then informs view of change
View changes visual presentation to reflect change

87. 13.17 Thinking About Objects (cont.)
Model-View-Controller in elevator simulation
Example
User presses First Floor of Second Floor Jbutton
Controller adds Person to model
Model notifies view of Person’s creation
View displays Person on Floor in response to notification

88. Fig. 13.22 Class diagram of the elevator simulation.

89. 13.17 Thinking About Objects (cont.)
Component diagram (UML)
Models “pieces” (components) used by system
e.g., .class file, .java files, images, packages, etc.
Notation
Components are represented as “plugs”
Packages are represented as “folders”
Dotted arrows indicate dependencies among components
Changing one component requires changing another

90. Fir. 13.23 Component diagram for elevator simulation

91. ElevatorSimulation.java Lines 12-13 Lines 19-21 Line 34
2 // Application with Elevator Model, View, and Controller (MVC)
3 package com.deitel.jhtp4.elevator; 4
5 // Java core packages
6 import java.awt.*; 7
8 // Java extension packages
9 import javax.swing.*; 10
11 // Deitel packages
12 import com.deitel.jhtp4.elevator.model.*;
13 import com.deitel.jhtp4.elevator.view.*;
14 import com.deitel.jhtp4.elevator.controller.*; 15
16 public class ElevatorSimulation extends JFrame { 17
// model, view and controller
private ElevatorModel model;
private ElevatorView view;
private ElevatorController controller; 22
// constructor instantiates model, view, and controller
public ElevatorSimulation() {
super( "Deitel Elevator Simulation" ); 27
// instantiate model, view and controller
model = new ElevatorModel();
view = new ElevatorView();
controller = new ElevatorController( model ); 32
// register View for Model events
model.setElevatorModelListener( view ); 35
ElevatorSimulation.java Lines Lines Line 34
Import packages model, view and controller
ElevatorSimulation aggregates one instance each of classes ElevatorModel, ElevatorView and ElevatorController
Register ElevatorModel as listener for ElevatorView

92. ElevatorSimulation.java Lines 37-38
// add view and controller to ElevatorSimulation
getContentPane().add( view, BorderLayout.CENTER );
getContentPane().add( controller, BorderLayout.SOUTH ); 39
} // end ElevatorSimulation constructor 41
// main method starts program
public static void main( String args[] ) {
// instantiate ElevatorSimulation
ElevatorSimulation simulation = new ElevatorSimulation();
simulation.setDefaultCloseOperation( EXIT_ON_CLOSE );
simulation.pack();
simulation.setVisible( true ); }
51 }
Add ElevatorView and ElevatorController to ElevatorSimulation
ElevatorSimulation.java Lines 37-38

93. Continue design-patterns discussion
(Optional) Discovering Design Patterns: Design Patterns Used in Packages java.awt and javax.swing
Continue design-patterns discussion
Design patterns associated with Java GUI components
GUI components take advantage of design patterns

94. 13.18.1 Creational Design Patterns
Factory Method design pattern
Suppose we design system that opens image from file
Several image formats exist (e.g., GIF, JPEG, etc.)
Each image format has different structure
Method createImage of class Component creates Image
Two Image objects (one for GIF image, one for JPEG image)
Method createImage uses parameter to determine proper Image subclass from which to instantiate Image object
createImage( "image.gif" );
Returns Image object with GIF data
createImage( "image.jpg" );
Returns Image object with JPEG data
Method createImage is called a factory method
Determines subclass to instantiate object at run time

95. 13.18.2 Structural Design Patterns
Adapter design pattern
Used with objects with incompatible interfaces
Allows these objects to collaborate with each other
Object’s interface adapts to another object’s interface
Similar to adapter for plug on electrical device
European electrical sockets differ from those in United States
American plug will not work with European socket
Use adapter for plug
Class MouseAdapter
Objects that generate MouseEvents adapts to objects that handle MouseEvents

96. 13.18.2 Structural Design Patterns (cont.)
Bridge design pattern
Design class Button for Windows and Macintosh systems
Class contains button information (e.g., String label)
Subclasses Win32Button and MacButton
Contain look-and-feel information
Problem with this approach
Creating class ImageButton (subclass of Button)
Requires creating Win32ImageButton and MacImageButton
Solution:
Separate abstraction (i.e., Button) from implementation (i.e., Win32Button and MacButton)
Button contains reference (bridge) to ButtonPeer
Handles platform-specific implementations

97. 13.18.2 Structural Design Patterns (cont.)
Composite design pattern
Organize components into hierarchical structures
Each node represents component
All nodes implement same interface
Polymorphism ensures clients traverse all nodes uniformly
Used by Swing components
JPanel is JContainer subclass
JPanel object can contain GUI component
JPanel remains unaware of component’s specific type

98. Fig. 13.25 Inheritance hierarchy for class JPanel.

99. 13.18.3 Behavioral Design Patterns
Chain-of-Responsibility design pattern
Determine object that handles message at run time
Three-line office-phone system
First line handles call
If first line is busy, second line handles call
If second line is busy, third line handles call
Message sent through “chain”
Each object in chain decides whether to handle message
If unable to handle message, that object sends message to next object in chain
Method processEvent of class Button
Handles AWTEvent or sends to next object

100. 13.18.3 Behavioral Design Patterns (cont.)
Command design pattern
Applications provide several ways to perform same task
Edit menu with menu items for cutting and copying text
Toolbar and popup menus may offer same feature
Encapsulate functionality (command) in reusable object
e.g., “cut text” functionality
Functionality can then be added to menus, toolbars, etc.
Developers code functionality only once

101. 13.18.3 Behavioral Design Patterns (cont.)
Observer design pattern
Design program for viewing bank-account information
Class BankStatementData store bank-statement data
Class TextDisplay displays data in text format
Class BarGraphDisplay displays data in bar-graph format
Class PieChartDisplay displays data in pie-chart format
BankStatementData (subject) notifies Display classes (observers) to display data when it changes
Subject notifies observers when subject changes state
Observers act in response to notification
Promotes loose coupling
Used by
class java.util.Observable
class java.util.Observer

102. Fig. 13.26 Basis for the Observer design pattern.

103. 13.18.3 Behavioral Design Patterns (cont.)
Strategy design pattern
Encapsulates algorithm
LayoutManagers are strategy objects
Classes FlowLayout, BorderLayout, GridLayout, etc.
Implement interface LayoutManager
Each class uses method addLayoutComponent
Each method implementation uses different algorithm
FlowLayout adds components left-to-right
BorderLayout adds components in five regions
GridLayout adds components in specified grid
Class Container has LayoutManager reference
Use method setLayout
Select different layout manager at run time

104. 13.18.3 Behavioral Design Patterns (cont.)
Template Method design pattern
Objects share single algorithm defined in superclass
Consider Fig.13.26
Display objects use same algorithm to acquire and display data
Get statements from BankStatementData
Parse statements
Display statements
Create superclass BankStatementDisplay
Provides methods that comprise algorithm
Subclasses override “display” method, because each subclass displays data differently