quoteoptionspanel.java

Java 程序设计教程（第五版）EXAMPLESchap05源码

//********************************************************************
//  QuoteOptionsPanel.java       Author: Lewis/Loftus
//
//  Demonstrates the use of radio buttons.
//********************************************************************

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

public class QuoteOptionsPanel extends JPanel
{
   private JLabel quote;
   private JRadioButton comedy, philosophy, carpentry;
   private String comedyQuote, philosophyQuote, carpentryQuote;

   //-----------------------------------------------------------------
   //  Sets up a panel with a label and a set of radio buttons
   //  that control its text.
   //-----------------------------------------------------------------
   public QuoteOptionsPanel()
   {
      comedyQuote = "Take my wife, please.";
      philosophyQuote = "I think, therefore I am.";
      carpentryQuote = "Measure twice. Cut once.";

      quote = new JLabel (comedyQuote);
      quote.setFont (new Font ("Helvetica", Font.BOLD, 24));

      comedy = new JRadioButton ("Comedy", true);
      comedy.setBackground (Color.green);
      philosophy = new JRadioButton ("Philosophy");
      philosophy.setBackground (Color.green);
      carpentry = new JRadioButton ("Carpentry");
      carpentry.setBackground (Color.green);

      ButtonGroup group = new ButtonGroup();
      group.add (comedy);
      group.add (philosophy);
      group.add (carpentry);

      QuoteListener listener = new QuoteListener();
      comedy.addActionListener (listener);
      philosophy.addActionListener (listener);
      carpentry.addActionListener (listener);

      add (quote);
      add (comedy);
      add (philosophy);
      add (carpentry);

      setBackground (Color.green);
      setPreferredSize (new Dimension(300, 100));
   }

   //*****************************************************************
   //  Represents the listener for all radio buttons
   //*****************************************************************
   private class QuoteListener implements ActionListener
   {
      //--------------------------------------------------------------
      //  Sets the text of the label depending on which radio
      //  button was pressed.
      //--------------------------------------------------------------
      public void actionPerformed (ActionEvent event)
      {
         Object source = event.getSource();

         if (source == comedy)
            quote.setText (comedyQuote);
         else
            if (source == philosophy)
               quote.setText (philosophyQuote);
            else
               quote.setText (carpentryQuote);
      }
   }
}