pushcounterpanel.java

Java 程序设计教程（第五版）EXAMPLESchap04源码

//********************************************************************
//  PushCounterPanel.java       Authors: Lewis/Loftus
//
//  Demonstrates a graphical user interface and an event listener.
//********************************************************************

import java.awt.*;
import java.awt.event.*;
import javax.swing.*;

public class PushCounterPanel extends JPanel
{
   private int count;
   private JButton push;
   private JLabel label;

   //-----------------------------------------------------------------
   //  Constructor: Sets up the GUI.
   //-----------------------------------------------------------------
   public PushCounterPanel ()
   {
      count = 0;

      push = new JButton ("Push Me!");
      push.addActionListener (new ButtonListener());

      label = new JLabel ("Pushes: " + count);

      add (push);
      add (label);

      setPreferredSize (new Dimension(300, 40));
      setBackground (Color.cyan);
   }

   //*****************************************************************
   //  Represents a listener for button push (action) events.
   //*****************************************************************
   private class ButtonListener implements ActionListener
   {
      //--------------------------------------------------------------
      //  Updates the counter and label when the button is pushed.
      //--------------------------------------------------------------
      public void actionPerformed (ActionEvent event)
      {
         count++;
         label.setText("Pushes: " + count);
      }
   }
}