awteventlistenerdemo.java

来自「《java事件处理指南》一书的代码,好东西」· Java 代码 · 共 70 行

import java.awt.*;
import java.awt.event.*;

public class AWTEventListenerDemo extends Frame 
{
   private Button button1, button2, button3;
   private TextField tf;
   private int count;

   public AWTEventListenerDemo()
   {

/*  Three buttons and a TextField are placed on a frame   */

      button1 = new Button("button1");
      button2 = new Button("button1");
      button3 = new Button("button1");

      tf = new TextField(20);
      tf.setEditable(false);

      Panel panel = new Panel();
      panel.add(button1);
      panel.add(button2);
      panel.add(button3);
      add(panel, BorderLayout.CENTER);
      add(tf, BorderLayout.SOUTH);

/*  A Toolkit object is obtained and it is used to register an  */
/*  AWTEventListener to passively listen for ActionEvents.      */

      Toolkit.getDefaultToolkit().addAWTEventListener(
            new AWTEventHandler(), AWTEvent.ACTION_EVENT_MASK);

      addWindowListener(new WinAdapter());
      setBounds(100, 100, 300, 200);
      setVisible(true);
   }

/*   The AWTEventListener is implemented as an inner class.  Whenever  */
/*   an ActionEvent is generated by any source, it is sent to the      */
/*   eventDispatched() method.  In this case, the method has been      */
/*   overridden to keep a running count of the number of ActionEvents  */
/*   that have been generated.                                         */

   class AWTEventHandler implements AWTEventListener
   {
      public void eventDispatched(AWTEvent event)
      {
         ++count;
         tf.setText("Buttons pressed "+count+" times");
      }
   }

   public static void main(String args[])
   {
      AWTEventListenerDemo demo = new AWTEventListenerDemo();
   }
}

/*  This makes sure the application terminates if the window is closed  */

class WinAdapter extends WindowAdapter
{
   public void windowClosing(WindowEvent event) 
   {
      System.exit(0);
   }
}