buttonpanel.java

来自「经典教材：java核心技术卷1、卷2的所有源代码」· Java 代码 · 共 61 行

/**
   @version 1.32 2004-05-11
   @author Cay Horstmann
*/

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

/**
   A panel with three buttons
*/
class ButtonPanel extends JPanel
{  
   public ButtonPanel()
   {  
      // create buttons

      JButton yellowButton = new JButton("Yellow");
      JButton blueButton = new JButton("Blue");
      JButton redButton = new JButton("Red");

      // add buttons to panel

      add(yellowButton);
      add(blueButton);
      add(redButton);

      // create button actions

      ColorAction yellowAction = new ColorAction(Color.YELLOW);
      ColorAction blueAction = new ColorAction(Color.BLUE);
      ColorAction redAction = new ColorAction(Color.RED);

      // associate actions with buttons

      yellowButton.addActionListener(yellowAction);
      blueButton.addActionListener(blueAction);
      redButton.addActionListener(redAction);
   }

   /**
      An action listener that sets the panel's background color. 
   */
   private class ColorAction implements ActionListener
   {  
      public ColorAction(Color c)
      {  
         backgroundColor = c;
      }

      public void actionPerformed(ActionEvent event)
      {  
         setBackground(backgroundColor);
      }

      private Color backgroundColor;
   }
}