Radio Buttons

Radio Buttons require two objects. They need all a radio button for each of the options that you require and they need a button group to group all of the radio buttons. The button group is to restrict the user to one selection in the group - that is how radio buttons work, the user gets only one selection of the list.

Basic Pieces of Code:

Declare button group to hold all of the buttons	ButtonGroup bg1 = new ButtonGroup ();
Declare string constants for each button's action command and label - this is not necessary, you can just type it out wherever the constants are used.	protected final static String Pascal = "Blaise Pascal";
Declare a radio button for each option.	JRadioButton pas = new JRadioButton ();
Set up the options for the radio button, add action listeners.	pas.setText (Pascal); pas.setActionCommand (Pascal); pas.addActionListener (this);
For ONE radio button in the group, set it to default to turn on.	pas.setSelected (true);
Add the radio button to the button group	bg1.add (pas);
Add the radio button to the screen. You do NOT add the button group.	add (pas);

Panels can be used to make the radio buttons arrange themselves more nicely.

The Complete Code:

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

public class radiobuttons extends Applet implements ActionListener
   {
   //constants for action commands
   protected final static String Pascal = "Blaise Pascal";
   protected final static String Wiles = "Andrew Wiles";
   protected final static String Turing = "Alan Turing";
   protected final static String Brooks = "Fred Brooks";

 ButtonGroup bg1 = new ButtonGroup ();
   JPanel p1 = new JPanel (new FlowLayout ());

 public void init ()
   {
   JRadioButton pas = new JRadioButton ();
   pas.setText (Pascal);
   pas.setActionCommand (Pascal);
   pas.addActionListener (this);
   pas.setSelected (true);
   bg1.add (pas);

 JRadioButton wil = new JRadioButton ();
   wil.setText (Wiles);
   wil.setActionCommand (Wiles);
   wil.addActionListener (this);
   bg1.add (wil);

 JRadioButton tur = new JRadioButton ();
   tur.setText (Turing);
   tur.setActionCommand (Turing);
   tur.addActionListener (this);
   bg1.add (tur);

 JRadioButton bro = new JRadioButton ();
   bro.setText (Brooks);
   bro.setActionCommand (Brooks);
   bro.addActionListener (this);
   bg1.add (bro);

 add (pas);
   add (wil);
   add (tur);
   add (bro);
   }

   /**
   Displays the name and clears the text field
   @param e.getActionCommand contains nothing or clearArea
   */
   public void actionPerformed (ActionEvent e)
   {
   String command = e.getActionCommand ();
   showStatus (command + " was selected");
   if (Brooks.equals (command))
   {
   showStatus ("A Turing Award Winner was selected");
   }

 }
   }