JAVA PROGRAMMING

Week 7: Swing (part 2)

Java Programing
Plan 3
1. Menu
2. Dialog window
3. Other components: JFileChooser,
JColorChooser

Java Programing
Core Menu classes 4

Java Programing
JMenuBar, JMenu, and
JMenuItem 5
• These form the minimum set of classes needed to
construct a main menu for an application.
• JMenu and JMenuItem are also used by popup menus
à the foundation of the menu system.

Java Programing
JMenuBar [1] 6
• Is essentially a container for menus.
• Inherits JComponent
• Has only one constructor: default constructor.
àInitially the menu bar will be empty
àYou need to populate it with menus prior to use.
à Each application has one and only one menu bar.
• Methods:
• JMenu add(JMenu menu)
• Component add(Component menu, int idx)
• void remove(Component menu)
• void remove(int idx)

Java Programing
JMenuBar [2] 7
• Methods (cont.)
• int getMenuCount()
• MenuElement[] getSubElements()
• boolean isSelected()
• void setJMenuBar(JMenuBar mb)

Java Programing
JMenu [1] 8
• JMenu encapsulates a menu, which is populated with
JMenuItems.
• It is derived from JMenuItem à one JMenu can be a
selection in another JMenu à one menu to be a
submenu of another.
• Constructors:
• JMenu(String name)
• JMenu()
• Methods
• JMenuItem add(JMenuItem item)
• Component add(Component item, int idx)
• void addSeparator()

Java Programing
JMenu [2] 9
• Methods
• void insertSeparator(int idx)
• void remove(JMenuItem menu)
• void remove(int idx)
• int getMenuComponentCount()
• Component[ ] getMenuComponents()

Java Programing
JMenuItem 10
• JMenuItem encapsulates an element in a menu.
• JMenuItem is derived from AbstractButton, and
every item in a menu can be thought of as a special kind
of button à when a menu item is selected, an action
event is generated.
• Constructors:
• JMenuItem(String name)
• JMenuItem(Icon image)
• JMenuItem(String name, Icon image)
• JMenuItem(String name, int mnem)
• JMenuItem(Action action)
• Methods
• void setEnabled(boolean enable)

Java Programing
Example: Creation of main menu 11

Java Programing
1. //Demonstrate a simple main menu.
2.
3.
import java.awt.*;
import java.awt.event.*;
12
4. import javax.swing.*;
5. class MenuDemo implements ActionListener {
6. JLabel jlab;
7. MenuDemo() {
8. // Create a new JFrame container.
9. JFrame jfrm = new JFrame("Menu Demo");
10. // Specify FlowLayout for the layout manager.
11. jfrm.setLayout(new FlowLayout());
12. // Give the frame an initial size.
13. jfrm.setSize(220, 200);
14. //Terminate the program when the user closes the
15. application.
16. jfrm.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
17. // Create a label that will display the menu selection.
18. jlab = new JLabel();
19. // Create the menu bar.
Java Programing
20. JMenuBar jmb = new JMenuBar();
 13
1. // Create the File menu.
2. JMenu jmFile = new JMenu("File");
3. JMenuItem jmiOpen = new JMenuItem("Open");
4. JMenuItem jmiClose = new JMenuItem("Close");
5. JMenuItem jmiSave = new JMenuItem("Save");
6. JMenuItem jmiExit = new JMenuItem("Exit");
7. jmFile.add(jmiOpen);
8. jmFile.add(jmiClose);
9. jmFile.add(jmiSave);
10. jmFile.addSeparator();
11. jmFile.add(jmiExit);
12. jmb.add(jmFile);

Java Programing
1. // Create the Options menu.
2. JMenu jmOptions = new JMenu("Options"); 14
3. // Create the Colors submenu.
4. JMenu jmColors = new JMenu("Colors");
5. JMenuItem jmiRed = new JMenuItem("Red");
6. JMenuItem jmiGreen = new JMenuItem("Green");
7. JMenuItem jmiBlue = new JMenuItem("Blue");
8. jmColors.add(jmiRed);
9. jmColors.add(jmiGreen);
10. jmColors.add(jmiBlue);
11. jmOptions.add(jmColors);
12. // Create the Priority submenu.
13. JMenu jmPriority = new JMenu("Priority");
14. JMenuItem jmiHigh = new JMenuItem("High");
15. JMenuItem jmiLow = new JMenuItem("Low");
16. jmPriority.add(jmiHigh);
17. jmPriority.add(jmiLow);
18. jmOptions.add(jmPriority);
Java Programing
1. // Create the Reset menu item.
2.
3.
JMenuItem jmiReset = new JMenuItem("Reset");
jmOptions.addSeparator(); jmOptions.add(jmiReset);
15
4. // Finally, add the entire options menu to the menu bar
5. jmb.add(jmOptions);
6. // Create the Help menu.
7. JMenu jmHelp = new JMenu("Help");
8. JMenuItem jmiAbout = new JMenuItem("About");
9. jmHelp.add(jmiAbout); jmb.add(jmHelp);
10. // Add action listeners for the menu items.
11. jmiOpen.addActionListener(this);
12. jmiClose.addActionListener(this);
13. jmiSave.addActionListener(this);
14. jmiExit.addActionListener(this);
15. jmiRed.addActionListener(this);
16. jmiGreen.addActionListener(this);
17. jmiBlue.addActionListener(this);
18. jmiHigh.addActionListener(this);
19. jmiLow.addActionListener(this);
20. jmiReset.addActionListener(this);
Java Programing
21. jmiAbout.addActionListener(this);
1. jfrm.add(jlab); // Add the label to the content pane.
2.
3.
// Add the menu bar to the frame.
jfrm.setJMenuBar(jmb);
16
4. jfrm.setVisible(true); // Display the frame.
5. }
6. //Handle menu item action events.
7. public void actionPerformed(ActionEvent ae) {
8. // Get the action command from the menu selection.
9. String comStr = ae.getActionCommand();
10. // If user chooses Exit, then exit the program.
11. if (comStr.equals("Exit")) System.exit(0);
12. // Otherwise, display the selection.
13. jlab.setText(comStr + " Selected");
14. }
15. public static void main(String args[]) {
16. // Create the frame on the event dispatching thread.
17. SwingUtilities.invokeLater(new Runnable() {
18. public void run() { new MenuDemo(); }
19. });
20. }
Java Programing
21. }
Add Mnemonics and Accelerators to
Menu Items 17
• In real applications: a menu usually includes support for
keyboard shortcuts à ability to select menu items rapidly.
• Two forms:
• mnemonics and
• accelerators.
• a mnemonic allows you to use the keyboard to select an
item from a menu that is already being displayed.
• An accelerator is a key that lets you select a menu item
without having to first activate the menu.

Java Programing
mnemonic [1] 18
• A mnemonic can be specified for both JMenuItem and
JMenu objects.
• Two ways to set the mnemonic for JMenuItem
• Using constructor : JMenuItem (String name, int mnem)
• Set the mnemonic : void setMnemonic (int mnem)
• mnem specifies the mnemonic. It should be one of the constants
defined in java.awt.event.KeyEvent, such as
KeyEvent.VK_F ou KeyEvent.VK_Z.
• Mnemonics are not case sensitive.

Java Programing
mnemonic [2] 19
• By default: the first matching letter in the menu item will
be underscored.
• In cases in which you want to underscore a letter other than the
first match:
void setDisplayedMnemonicIndex(int idx)
• The index of the letter to underscore is specified by idx.

Java Programing
Accelerator [1] 20
• An accelerator can be associated with a JMenuItem
object.
• It is specified by calling
void setAccelerator (KeyStroke ks)
• ks is the key combination that is pressed to select the menu item.
• KeyStroke is a class that contains several factory methods that
construct various types of keystroke accelerators.
• Example:
• static KeyStroke getKeyStroke(char ch)
• static KeyStroke getKeyStroke(Character ch, int
modifier)
• static KeyStroke getKeyStroke(int ch, int modifier)
• ch specifies the accelerator character.

Java Programing
Accelerator [2] 21
• modifier must be one or more of the following constants,
defined in the java.awt.event.InputEvent class :

• If you pass VK_A for the key character and

Java Programing
1. // Create the File menu with mnemonics and accelerators.
2.

3.
jmFile.setMnemonic(KeyEvent.VK_F);
JMenuItem jmiOpen = new JMenuItem("Open", KeyEvent.VK_O);
22
4. jmiOpen.setAccelerator(KeyStroke.getKeyStroke(KeyEvent.VK_O,
5. InputEvent.CTRL_DOWN_MASK));
6. JMenuItem jmiClose = new JMenuItem("Close", KeyEvent.VK_C);
7. jmiClose.setAccelerator(KeyStroke.getKeyStroke(KeyEvent.VK_C,
8. InputEvent.CTRL_DOWN_MASK));
9. JMenuItem jmiSave = new JMenuItem("Save", KeyEvent.VK_S);
10. jmiSave.setAccelerator(KeyStroke.getKeyStroke(KeyEvent.VK_S,
11. InputEvent.CTRL_DOWN_MASK));
12. JMenuItem jmiExit = new JMenuItem("Exit", KeyEvent.VK_E);
13. jmiExit.setAccelerator(KeyStroke.getKeyStroke(KeyEvent.VK_E,
14. InputEvent.CTRL_DOWN_MASK));

Java Programing
Add Images and Tooltips to Menu
Items [1] 23
• You can add images to menu items or use images
instead of text.
• Constructors:
• JMenuItem(Icon image)
• JMenuItem(String name, Icon image)
• Example:
• ImageIcon icon = new ImageIcon("AboutIcon.gif");
• JMenuItem jmiAbout = new JMenuItem("About",
icon);

Java Programing
Add Images and Tooltips to Menu
Items [2] 24
• To add an icon to a menu item (inherit from
AbstractButton)
• void setIcon(Icon defaultIcon)
• To specify horizontal alignment of image:
• void setHorizontalAlignment(int alignment)
• To specify a disabled icon:
• void setDisabledIcon(Icon disabledIcon)

Java Programing
Tooltip 25
• A tooltip is a small message that describes an item.
• It is automatically displayed if the mouse remains over
the item for a moment.
• To add a tooltip to a menu item:
• void setToolTipText(String msg)
• Example
jmiAbout.setToolTipText
("Info about the MenuDemo program.");

Java Programing
JRadioButtonMenuItem and
JCheckBoxMenuItem 26
• Menu items are the most commonly used.
• Swing defines two others: check boxes and radio buttons.
• Allow a menu to provide functionality that would otherwise
require additional, standalone components.
• Sometimes, including check boxes or radio buttons in a menu
simply seems the most natural place for a specific set of features.
• To add a check box to a menu: create a
JCheckBoxMenuItem.
• Constructors :
• JCheckBoxMenuItem(String name)
• JCheckBoxMenuItem(String name, boolean state)
• JCheckBoxMenuItem(String name, Icon icon)

Java Programing
 Example: JCheckBoxMenuItem 27
1. // Use check boxes for colors. This allows
2. // the user to select more than one color.
3. JCheckBoxMenuItem jmiRed = new JCheckBoxMenuItem("Red", true);
4. JCheckBoxMenuItem jmiGreen = new JCheckBoxMenuItem("Green", false);
5. JCheckBoxMenuItem jmiBlue = new JCheckBoxMenuItem("Blue", false);

Java Programing
JRadioButtonMenuItem 28

• Constructors
• JRadioButtonMenuItem(String name)
• JRadioButtonMenuItem(String name, boolean state)
• JRadioButtonMenuItem(String name, Icon icon,
boolean state)
• Example
JRadioButtonMenuItem jmiHigh =
new JRadioButtonMenuItem("High", true);
JRadioButtonMenuItem jmiLow =
new JRadioButtonMenuItem("Low");
// Create button group for the radio button menu items.
ButtonGroup bg = new ButtonGroup();
bg.add(jmiHigh); bg.add(jmiLow);

Java Programing
Create a Popup Menu [1] 29
• A popular alternative or addition to the menu bar.
• A popup menu is activated by clicking the right mouse
button when over a component.
• Constructors
• JPopupMenu()
• JPopupMenu(String label)
• Popup menus are constructed like regular menus
• First, create a JPopupMenu object, and then add menu items to
it.
• Menu item selections are also handled in the same way: by
listening for action events.

Java Programing
Create a Popup Menu [2] 30
• The main difference between a popup menu and regular
menu: the activation process.
1. You must register a listener for mouse events.
2. Inside the mouse event handler, you must watch for the popup
trigger.
3. When a popup trigger is received, you must show the popup
menu by calling show( ).
• To listen for the popup trigger:
• Implement the MouseListener interface and
• Register the listener by calling the addMouseListener( )
method

Java Programing
Create a Popup Menu [3] 31
• Methods of MouseListener:
• void mouseClicked(MouseEvent me)
• void mouseEntered(MouseEvent me)
• void mouseExited(MouseEvent me)
• void mousePressed(MouseEvent me)
• void mouseReleased(MouseEvent me)
• Four methods of MouseEvent class are commonly
needed when activating a popup menu:
• int getX( )
• int getY( )
• boolean isPopupTrigger( )
• Component getComponent( )

Java Programing
1. // Create an Edit popup menu.
2. JPopupMenu jpu = new JPopupMenu(); 32
3. // Create the popup menu items
4. JMenuItem jmiCut = new JMenuItem("Cut");
5. JMenuItem jmiCopy = new JMenuItem("Copy");
6. JMenuItem jmiPaste = new JMenuItem("Paste");
7. // Add the menu items to the popup menu.
8. jpu.add(jmiCut); jpu.add(jmiCopy); jpu.add(jmiPaste);
9. // Add a listener for for the popup trigger.
10. jfrm.addMouseListener(new MouseAdapter() {
11. public void mousePressed(MouseEvent me) {
12. if(me.isPopupTrigger())
13. jpu.show(me.getComponent(), me.getX(), me.getY());
14. }
15. public void mouseReleased(MouseEvent me) {
16. if(me.isPopupTrigger())
17. jpu.show(me.getComponent(), me.getX(), me.getY());
18. }
Java Programing
19. });
Toolbar 33
• A toolbar is a component that can serve as both an
alternative and as an adjunct to a menu.
• A toolbar contains a list of buttons (or other components)
that give the user immediate access to various program
options.
• In general:
• Toolbar buttons show icons rather than text, although either or
both are allowed.
• Tooltips are often associated with icon-based toolbar buttons.
• Toolbars can be positioned on any side of a window by
dragging the toolbar, or they can be dragged out of the
window entirely, in which case they become free floating.

Java Programing
Create a Toolbar [1] 34
• To create a toolbar: JToolBar
• Constructors
• JToolBar ()
• JToolBar (String title)
• JToolBar (int how)
• JToolBar (String title, int how)
• To add buttons (or other components) to a toolbar: Use
add().

Java Programing
1. // Create a Debug tool bar.
2.
3.
JToolBar jtb = new JToolBar("Debug");
// Load the images.
35
4. ImageIcon set = new ImageIcon("setBP.gif");
5. ImageIcon clear = new ImageIcon("clearBP.gif");
6. ImageIcon resume = new ImageIcon("resume.gif");
7. // Create the tool bar buttons.
8. JButton jbtnSet = new JButton(set);
9. jbtnSet.setActionCommand("Set Breakpoint");
10. jbtnSet.setToolTipText("Set Breakpoint");
11. JButton jbtnClear = new JButton(clear);
12. jbtnClear.setActionCommand("Clear Breakpoint");
13. jbtnClear.setToolTipText("Clear Breakpoint");
14. JButton jbtnResume = new JButton(resume);
15. jbtnResume.setActionCommand("Resume");
16. jbtnResume.setToolTipText("Resume");
17. // Add the buttons to the toolbar.
18. jtb.add(jbtnSet); jtb.add(jbtnClear); jtb.add(jbtnResume)
19. jfrm.add(jtb, BorderLayout.NORTH);
Java Programing
Plan du cours 36
1. Menu
2. Dialog window
3. Other components: JFileChooser,
JColorChooser

Java Programing
Dialog window 37
• An independent subwindow meant to carry temporary
notice apart from the main Swing Application Window.
• Most Dialogs present an error message or warning to a
user, but Dialogs can present images, directory trees, or
just about anything compatible with the main Swing
Application that manages them.
• Several Swing component classes can directly instantiate
and display dialogs.

Java Programing
Examples of Dialog windows 38
• To create simple, standard dialogs: use the
JOptionPane class.
• The ProgressMonitor class can put up a dialog that
shows the progress of an operation.
• JColorChooser and JFileChooser supply standard
dialogs.
• To bring up a print dialog, you can use the Printing API.
• To create a custom dialog, use the JDialog class
directly.

Java Programing
Overview of Dialogs [1] 39
• Every dialog is dependent on a Frame component.
• When that Frame is destroyed: its dependent Dialogs are
destroyed, too.
• When the frame is iconified: its dependent Dialogs also
disappear from the screen.
• When the frame is deiconified: its dependent Dialogs return to
the screen.
• A Swing JDialog class inherits this behavior from the
AWT Dialog class.
• A Dialog can be modal.
• JOptionPane creates JDialogs that are modal.
• To create a non-modal Dialog: use the JDialog class directly.

Java Programing
Overview of Dialogs [2] 40
• From JDK 7: you can modify dialog window modality
behavior using the new Modality API. For more
information: click HERE.
• The JDialog class is a subclass of the
AWT java.awt.Dialog class.
• It adds a root pane container and support for a default close
operation to the Dialog object .
• When you use JOptionPane to implement a dialog,
you're still using a JDialog behind the scenes.
• Reason: JOptionPane is simply a container that can
automatically create a JDialog and add itself to the JDialog's
content pane.

Java Programing
JOptionPane Features 41
• JOptionPane provides support for laying out standard
dialogs, providing icons, specifying the dialog title and
text, and customizing the button text.
• Allow you to customize the components the dialog
displays and specify where the dialog should appear
onscreen.
• You can even specify that
an option pane put itself
into an internal frame
(JInternalFrame) instead
of a JDialog.

Java Programing
Example 42
JOptionPane.showMessageDialog(frame,
"Eggs are not supposed to be green.");

Java Programing
Methodes of JOptionPane 43
• showConfirmDialog()
• Asks a confirming question, like yes/no/cancel.
• showInputDialog()
• Prompt for some input.
• showMessageDialog()
• Tell the user about something that has happened.
• showOptionDialog()
• The Grand Unification of the above three.
à showXxxDialog

Java Programing
Arguments of showXxxDialog [1] 44

• Component parentComponent
• the parent component, which must be a Frame, a component inside
a Frame, or null.
• Object message
• specifies what the dialog should display in its main area.
• String title
• The title of the dialog.
• int optionType
• Specifies the set of buttons that appear at the bottom of the dialog.
• Values: DEFAULT_OPTION, YES_NO_OPTION,
YES_NO_CANCEL_OPTION, OK_CANCEL_OPTION.

Java Programing
Arguments of showXxxDialog [2] 45
• int messageType
• determines the icon displayed in the dialog.
• Values: PLAIN_MESSAGE (without icon), ERROR_MESSAGE,
INFORMATION_MESSAGE,WARNING_MESSAGE,
QUESTION_MESSAGE.
• Icon icon
• The icon to display in the dialog.
• Object[] options
• specify the string displayed by each button at the bottom of the
dialog.
• Object initialValue
• Specifies the default value to be selected.

Java Programing
 Example 46
1.
//Custom button text
2.
Object[] options = {"Yes, please", "No, thanks",
3.
"No eggs, no ham!"};
4.
int n = JOptionPane.showOptionDialog(frame,
5.
"Would you like some green eggs to go with that ham?",
6.
"A Silly Question", JOptionPane.YES_NO_CANCEL_OPTION,
7.
JOptionPane.QUESTION_MESSAGE, null, options,
8.
options[2]);

Java Programing
Obtaining user input from a dialog
window 47
• Only showInputDialog returns an Object.
• This Object is generally a String reflecting the user's choice.
• Example:
String name = JOptionPane.showInputDialog(frame,
"Please enter your name: ",
"Personal information",
JOptionPane.QUESTION_MESSAGE);

JOptionPane.showMessageDialog(frame, "Your name is " +

Java Programing
Result 48

Java Programing
Create a custom dialog 49
• Create a class which extends JDialog.

Java Programing
 Example 50
1. public class MyDialog extends JDialog {
2. MyDialog(JFrame parent, String title, boolean modal){
3. // We call the corresponding JDialog constructor
4. super(parent, title, modal);
5. // We specify the size of the dialog
6. this.setSize(200, 80);
7. // The position
8. this.setLocationRelativeTo(null);
9. // The box should not be resizable
10. this.setResizable(false);
11. // Finally we display it
12. this.setVisible(true);
13. }
} Java Programing
1. public class MyDialogDemo extends JFrame {
2. private JButton button = new 51
3. JButton("Invoke MyDialog");
4. public MyDialogDemo() {
5. setTitle("My JFrame"); setSize(300, 100);
6. setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
7. setLocationRelativeTo(null);
8. getContentPane().setLayout(new FlowLayout());
9. getContentPane().add(button);
10. button.addActionListener(new ActionListener(){
11. public void actionPerformed(ActionEvent ae) {
12. new MyDialog(null, "Hello, my dialog", true);
13. }
14. });
15. this.setVisible(true);
16. }
17. public static void main(String[] args){
18. new MyDialogDemo();
Java Programing
19. }
 Example (improved version) 52
1. public class MyDialog extends JDialog {
2. MyDialog(JFrame parent, String title, boolean modal){
3. super(parent, title, modal);
4. this.setSize(200, 80);
5. this.setLocationRelativeTo(null);
6. this.setResizable(false);
7. this.initComponent();
8. this.setVisible(true);
9. }
10. public void initComponent() {
11. /* initialize components and add them into the
12. content pane by calling
13. this.getContentPane().add(...);
14. */
15. }
Java Programing
16. }
Plan 53
1. Menu
2. Dialog window
3. Other components: JFileChooser,
JColorChooser

Java Programing
File Choosers 54
• Provide a GUI for navigating the file system, and then
either choosing a file or directory from a list, or entering
the name of a file or directory.
• To display a file chooser: use the JFileChooser API to
show a modal dialog containing the file chooser.
• Another way: add an instance of JFileChooser to a container.
• The JFileChooser API makes it easy to create open
and saved dialogs.
• To know more:
• https://docs.oracle.com/javase/tutorial/uiswing/components/filech
ooser.html

Java Programing
 Example 55
1. //Create a file chooser
2. final JFileChooser fc = new JFileChooser();
3. // ...
4. //In response to a button click:
5. int returnVal = fc.showOpenDialog(aComponent);
6.

7. // ...
8.

9. if (returnVal == JFileChooser.APPROVE_OPTION) {
10. File file = fc.getSelectedFile();
11. // ...
12. } else {
13. // ...
14. } Java Programing
Color Choosers 56
• Enable users to choose from a palette of colors.
• Is a component that you can place anywhere within your
program GUI.
• The JColorChooser API also makes it easy to bring up
a dialog (modal or not) that contains a color chooser.
• To know more:
• https://docs.oracle.com/javase/tutorial/uiswing/components/color
chooser.html

Java Programing
 57

QUESTION ?

Java Programing