radiobuttons.java

《A first book of java》by Gary J.Bronson 北大出版社

import java.text.*;  // need this for formatting
import javax.swing.*;
import java.awt.event.*;
import java.awt.Container;  // need this to add controls
import java.awt.*;  // need this for layout manager 
public class RadioButtons extends JFrame
{
  private JFrame mainFrame;
  private JButton exitButton;
  private JLabel inLabel;
  private JTextField tinField;
  private JRadioButton rdbutCourier;
  private JRadioButton rdbutSansSerif;
  private JRadioButton rdbutSerif;
                               
  public RadioButtons() // a constructor
  {
    mainFrame = new JFrame("Radio Button Example");

      // create all components
    
    exitButton = new JButton("Exit");
    inLabel = new JLabel("Enter Some Text:");
    tinField = new JTextField(20);
    rdbutCourier = new JRadioButton("Courier");
    rdbutSansSerif = new JRadioButton("SansSerif");
    rdbutSerif = new JRadioButton("Serif");

      // put the buttons into a single group
    ButtonGroup rgroup = new ButtonGroup();
    rgroup.add(rdbutCourier);
    rgroup.add(rdbutSansSerif); 
    rgroup.add(rdbutSerif);
                            
      // get the content pane 
    Container c = mainFrame.getContentPane(); 
      // set the layout managare
    c.setLayout(new FlowLayout());
    
      // add the components to the ContentPane 
    c.add(inLabel);
    c.add(tinField);
    c.add(rdbutCourier);
    c.add(rdbutSansSerif);
    c.add(rdbutSerif);
    c.add(exitButton);

        // create accelerator keys
    rdbutCourier.setMnemonic('C');
    rdbutSansSerif.setMnemonic('S');
    rdbutSerif.setMnemonic('f');
    exitButton.setMnemonic('x');

      // set the initial button and corresponding font
    rdbutCourier.setSelected(true);
    tinField.setFont(new Font("Courier",Font.PLAIN, 12));

    mainFrame.setSize(300,150);

       // define and register window event handler
    mainFrame.addWindowListener(new WindowAdapter()
    {
      public void windowClosing(WindowEvent e) {System.exit(0);}
    });
    
      // create and register the event handlers
 
    ExitButtonHandler ehandler = new ExitButtonHandler();  // instantiate a handler
    exitButton.addActionListener(ehandler);  // register the handler    

    RButHandler rhandler = new RButHandler();
    rdbutCourier.addItemListener(rhandler);
    rdbutSansSerif.addItemListener(rhandler);
    rdbutSerif.addItemListener(rhandler);
        
    mainFrame.show();
  } 
    
     // inner classes for the Radio Button handlers
   class RButHandler implements ItemListener
   {
     public void itemStateChanged(ItemEvent e)
     {
      
       if (e.getSource() == rdbutCourier)
           tinField.setFont(new Font("Courier",Font.PLAIN, 12));
       else if (e.getSource() == rdbutSansSerif)
           tinField.setFont(new Font("SansSerif",Font.PLAIN, 12));
       else if (e.getSource() == rdbutSerif)
           tinField.setFont(new Font("Serif",Font.PLAIN, 12));

       tinField.repaint();
     }
   }  // end of inner class         
 
     // inner class for the Exit button event handler
  class ExitButtonHandler implements ActionListener
  {
    public void actionPerformed(ActionEvent e)
    {
      System.exit(0);
    }
  }  // end of inner class


  public static void main(String args[])
  {
    new RadioButtons();  // instantiate a GUI object 
  }

}  // end of class