jradiobuttondemo.java

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// 例 6.3.2  JRadioButtonDemo.java
import javax.swing.*;
import java.awt.event.*;
public class JRadioButtonDemo implements ActionListener
{
	private JFrame jframe;
	private JPanel jpl;
	private JRadioButton jrb1,jrb2,jrb3,jrb4;
	private JLabel jlb;
	private ButtonGroup bg;
	public JRadioButtonDemo()
{
		jframe = new JFrame("单选按钮演示窗口");
		jpl = new JPanel();
		jlb = new JLabel("请选择正确的答案");
		
		jrb1 = new JRadioButton("A");   // 创建单选按钮对象
		jrb1.addActionListener(this);  // 注册该对象到监听器
		jpl.add(jrb1);                 // 将该对象添加到面板中
		
		jrb2 = new JRadioButton("B");
		jrb2.addActionListener(this);
		jpl.add(jrb2);
		
		jrb3 = new JRadioButton("C");
		jrb3.addActionListener(this);
		jpl.add(jrb3);
		
		jrb4 = new JRadioButton("D");
		jrb4.addActionListener(this);
		jpl.add(jrb4);
		
		bg = new ButtonGroup();   // 创建一个按钮组
		bg.add(jrb1);bg.add(jrb2);bg.add(jrb3);bg.add(jrb4);
		
		jpl.add(jlb);
		jframe.getContentPane().add(jpl);
		jframe.pack();
		jframe.setVisible(true);
		jframe.addWindowListener(new WindowAdapter(){
			public void windowClosing(WindowEvent e){
				System.exit(0);
			}
		});
		 
	}
	public void actionPerformed(ActionEvent e)
{
		jlb.setText("您选择了答案："+e.getActionCommand());
	}
	public static void main(String[] args)
{
		new JRadioButtonDemo();
}
}