popuptest.java

这是java 2应用开发指南这本书上所有例子的源代码

import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
public class PopupTest extends JFrame {
  private JRadioButtonMenuItem items[];
  private Color colorValues[] = { Color.blue, Color.green, Color.red };
  private JPopupMenu popupMenu;
  public PopupTest(){
    super( "Using JPopupMenus" );
    ItemHandler handler = new ItemHandler();
    String colors[] = { "Blue", "Green", "Red" };
    ButtonGroup colorGroup = new ButtonGroup();
    popupMenu = new JPopupMenu();
    items = new JRadioButtonMenuItem[ 3 ];
    for ( int count = 0; count < items.length; count++ ) {
      items[ count ] = new JRadioButtonMenuItem( colors[ count ] );
      popupMenu.add( items[ count ] );
      colorGroup.add( items[ count ] );
      items[ count ].addActionListener( handler );
   }
   getContentPane().setBackground( Color.white );
   addMouseListener( new MouseAdapter() {
     public void mousePressed( MouseEvent event ){
       checkForTriggerEvent( event );
     }
    public void mouseReleased( MouseEvent event ) {
      checkForTriggerEvent( event );
    }
    private void checkForTriggerEvent( MouseEvent event ){
      if ( event.isPopupTrigger() )
        popupMenu.show( event.getComponent(), event.getX(), event.getY() );
   }
  });
   setSize( 300, 200 );
   setVisible( true );
  }
 public static void main( String args[] ){
   PopupTest application = new PopupTest();
   application.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE );
 }
 private class ItemHandler implements ActionListener {
   public void actionPerformed( ActionEvent event )
   {
     for ( int i = 0; i < items.length; i++ )
       if ( event.getSource() == items[ i ] ) {
         getContentPane().setBackground(colorValues[ i ] );
         repaint();
         return;
      }
    }
  }
}