JRadioButton

• JRadioButton ref
• How to use buttons

Textbook example

// RadioButtonTest.java
// Creating radio buttons using ButtonGroup and JRadioButton.
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;

public class RadioButtonTest extends JFrame {
   private JTextField t;
   private Font plainFont, boldFont,
                italicFont, boldItalicFont;
   private JRadioButton plain, bold, italic, boldItalic;
   private ButtonGroup radioGroup;

   public RadioButtonTest()
   {
      super( "RadioButton Test" );

      Container c = getContentPane();
      c.setLayout( new FlowLayout() );

      t = new JTextField( "Watch the font style change", 25 );
      c.add( t ); 

      // Create radio buttons
      plain = new JRadioButton( "Plain", true );
      c.add( plain );
      bold = new JRadioButton( "Bold", false);
      c.add( bold );
      italic = new JRadioButton( "Italic", false );
      c.add( italic );
      boldItalic = new JRadioButton( "Bold/Italic", false );
      c.add( boldItalic );

      // register events
      RadioButtonHandler handler = new RadioButtonHandler();
      plain.addItemListener( handler );
      bold.addItemListener( handler );
      italic.addItemListener( handler );
      boldItalic.addItemListener( handler );

      // create logical relationship between JRadioButtons
      radioGroup = new ButtonGroup();
      radioGroup.add( plain );
      radioGroup.add( bold );
      radioGroup.add( italic );
      radioGroup.add( boldItalic );

      plainFont = new Font( "TimesRoman", Font.PLAIN, 14 );
      boldFont = new Font( "TimesRoman", Font.BOLD, 14 );
      italicFont = new Font( "TimesRoman", Font.ITALIC, 14 );
      boldItalicFont =
         new Font( "TimesRoman", Font.BOLD + Font.ITALIC, 14 );
      t.setFont( plainFont );

      setSize( 300, 100 );
      show();
   }

   public static void main( String args[] )
   {
      RadioButtonTest app = new RadioButtonTest();

      app.addWindowListener(
         new WindowAdapter() {
            public void windowClosing( WindowEvent e )
            {
               System.exit( 0 );
            }
         }
      );
   }

   private class RadioButtonHandler implements ItemListener {
      public void itemStateChanged( ItemEvent e )
      {
         if ( e.getSource() == plain ) 
            t.setFont( plainFont );
         else if ( e.getSource() == bold ) 
            t.setFont( boldFont );
         else if ( e.getSource() == italic ) 
            t.setFont( italicFont );
         else if ( e.getSource() == boldItalic ) 
            t.setFont( boldItalicFont );

         t.repaint();
      }
   }
}

Maintained by John Loomis, last updated 1 June 2000