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Expertise: Intermediate
Language: Java

October 29, 1998

Creating Radio Buttons Using the AWT

The way you create a set of radio buttons is significantly different between Swing and the AWT. With Swing, you instantiate the buttons and add them to a group object rather than passing the group object as a parameter when you instantiate the buttons. To create radio buttons using the AWT, you instantiate a CheckboxGroup object and pass that object to the Checkbox constructor. Checkbox objects behave as mutually exclusive radio buttons and only one can be selected at a time. The following code was tested using JDK1.1.6 under Win95:

 
import java.awt.*;
import java.awt.event.*;
import java.util.*;
//=======================================================//
public class RadioButton01 extends Frame{
	public static void main(String[] args){
		new RadioButton01();
	}//end main

	RadioButton01(){//constructor
		//Create a CheckboxGroup object
		CheckboxGroup myCheckboxGroup = new CheckboxGroup();

		setLayout(new FlowLayout());    
		add(new Checkbox("A",true, myCheckboxGroup));
		add(new Checkbox("B",false,myCheckboxGroup));
		add(new Checkbox("C",false,myCheckboxGroup));

		setSize(250,100);
		setTitle("Radio Buttons");
		setVisible(true);
    
		// Inner class to terminate program.
		addWindowListener(new WindowAdapter() {
			public void windowClosing(WindowEvent e) {
			System.exit(0);}});//end WindowListener
	}//end constructor
}//end class RadioButton01 definition