testradiobuttondemo.java

爱java的下来看看

import java.awt.*;
import java.awt.event.*;

import javax.swing.*;

public class TestRadioButtonDemo extends JFrame implements ItemListener
{
	private JRadioButton jrbRed,jrbYellow,jrbGreen;
	private Light light;
    private ButtonGroup bg=new ButtonGroup();
	/**
	 * @param args
	 */
	public TestRadioButtonDemo()
	{
		this.setTitle("模拟交通灯");
		JPanel p1=new JPanel();
		p1.setSize(200,200);
		light=new Light();
		light.setSize(40,90);
		p1.add(light);
		
		JPanel p2=new JPanel();
		p2.add(jrbRed=new JRadioButton("Red"));
		p2.add(jrbYellow=new JRadioButton("Yellow"));
		p2.add(jrbGreen=new JRadioButton("Green"));
		
		bg.add(jrbRed);
		bg.add(jrbYellow);
		bg.add(jrbGreen);
		
		getContentPane().add(p1,BorderLayout.CENTER);
		getContentPane().add(p2,BorderLayout.SOUTH);
		
		jrbRed.addItemListener(this);
		jrbYellow.addItemListener(this);
		jrbGreen.addItemListener(this);
		
		
	}
	public static void main(String[] args) 
	{
		TestRadioButtonDemo frame=new TestRadioButtonDemo();
		frame.setSize(250,180);
		frame.setVisible(true);

	}

	public void itemStateChanged(ItemEvent e)
	{
		if(jrbRed.isSelected())
			light.turnOnRed();
		if(jrbYellow.isSelected())
			light.turnOnYellow();
		if(jrbGreen.isSelected())
			light.turnOnGreen();
		
	}

}
class Light extends JPanel
{
	private boolean red,yellow,green;
	
	public Light()
	{
		this.red=false;
		this.yellow=false;
		this.green=false;
	}

	public void turnOnRed() 
	{
		this.red=true;
		this.yellow=false;
		this.green=false;
		this.repaint();	
		
	}

	public void turnOnGreen() 
	{
		this.red=false;
		this.yellow=false;
		this.green=true;
		this.repaint();	
	}

	public void turnOnYellow() 
	{
		this.red=false;
		this.yellow=true;
		this.green=false;
		this.repaint();	
	}
	public void paintComponent(Graphics g)
	{
		super.paintComponent(g);
		
		if(red)
		{
			g.setColor(Color.red);
			g.fillOval(10, 10, 20, 20);
			g.setColor(Color.black);
			g.fillOval(10, 35, 20, 20);
			g.fillOval(10, 60, 20, 20);
			g.drawRect(5, 5, 30, 80);
		}
		else if(yellow)
		{
			g.setColor(Color.yellow);
			g.fillOval(10, 35, 20, 20);
			g.setColor(Color.black);
			g.fillOval(10, 10, 20, 20);
			g.fillOval(10, 60, 20, 20);
			g.drawRect(5, 5, 30, 80);
		}
		else if(green)
		{
			g.setColor(Color.green);
			g.fillOval(10, 60, 20, 20);
			g.setColor(Color.black);
			g.fillOval(10, 10, 20, 20);
			g.fillOval(10, 35, 20, 20);
			g.drawRect(5, 5, 30, 80);
		}
		else
		{
			g.setColor(Color.black);
			g.fillOval(10, 10, 20, 20);
			g.fillOval(10, 35, 20, 20);
			g.fillOval(10, 60, 20, 20);
			g.drawRect(5, 5, 30, 80);
		}
	}
	public Dimension getPreferredSize()
	{
		return new Dimension(40,90);
	}
	
}