JPopupMenu

01: // PopupTest.java
02: // Demonstrating JPopupMenus
03: import javax.swing.*;
04: import java.awt.event.*;
05: import java.awt.*;
06: 
07: class TestPanel extends JPanel {
08:    private JRadioButtonMenuItem items[];
09:    private Color colorValues[] = 
10:       { Color.blue, Color.yellow, Color.red };
11: 
12:    public TestPanel()
13:    {
14: 
15:       final JPopupMenu popupMenu = new JPopupMenu();
16:       ItemHandler handler = new ItemHandler();
17:       String colors[] = { "Blue", "Yellow", "Red" };
18:       ButtonGroup colorGroup = new ButtonGroup();
19:       items = new JRadioButtonMenuItem[ 3 ];
20: 
21:       // construct each menu item and add to popup menu; also
22:       // enable event handling for each menu item
23:       for ( int i = 0; i < items.length; i++ ) {         
24:          items[ i ] = new JRadioButtonMenuItem( colors[ i ] );
25:          popupMenu.add( items[ i ] );
26:          colorGroup.add( items[ i ] );
27:          items[ i ].addActionListener( handler );                
28:       }
29: 
30:      setBackground( Color.white );
31: 
32:       // define a MouseListener for the window that displays
33:       // a JPopupMenu when the popup trigger event occurs
34:       addMouseListener(
35:          new MouseAdapter() {
36:             public void mousePressed( MouseEvent e )
37:                { checkForTriggerEvent( e ); } 
38: 
39:             public void mouseReleased( MouseEvent e )
40:                { checkForTriggerEvent( e ); } 
41: 
42:             private void checkForTriggerEvent( MouseEvent e )
43:             {
44:                if ( e.isPopupTrigger() ) 
45:                   popupMenu.show( e.getComponent(),
46:                                   e.getX(), e.getY() );               
47:             }
48:          }
49:       );    
50:    }
51: 
52:    private class ItemHandler implements ActionListener {
53:       public void actionPerformed( ActionEvent e )
54:       {
55:          // determine which menu item was selected
56:          for ( int i = 0; i < items.length; i++ )
57:             if ( e.getSource() == items[ i ] ) {
58:                     setBackground(
59:                   colorValues[ i ] );
60:                repaint();
61:                return;
62:             }
63:       }
64:    }
65: }
66: 
67: public class PopupTest extends JApplet
68: {
69:     TestPanel panel;
70:     public void init()
71:     {
72:         panel = new TestPanel();
73:         getContentPane().add(panel);
74:     }
75: 
76:     public static void main( String args[] )
77:     {
78:         TestPanel panel = new TestPanel();
79:         JFrame frame = new JFrame("Using JPopupMenus" );
80:         frame.add(panel);
81:         frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
82:         frame.setSize( 300, 200 );
83:         frame.setVisible(true);
84:     }
85: }