Write a java program that simulates a traffic light.

Write a java program that simulates a traffic light. The program lets the user select one of three lights: red, yellow or green. When a radio button is selected, the light is turned on, and only one light can be on at a time. No light is on when the program starts.

Program Code:

import java.awt.*;

import java.awt.event.*;

class Traffic extends Frame implements ItemListener

{

String clr="";

Traffic()

{

Checkbox c1,c2,c3;

CheckboxGroup cbg=new CheckboxGroup();

c1=new Checkbox("red",true,cbg);

c2=new Checkbox("green",true,cbg);

c3=new Checkbox("yellow",true,cbg);

setSize(500,500);

setTitle("Traffic Signal");

setVisible(true);

setLayout(new FlowLayout(FlowLayout.CENTER));

add(c1); add(c2); add(c3);

c1.addItemListener(this);

c2.addItemListener(this);

c3.addItemListener(this);

addWindowListener(new WindowAdapter()

{

public void windowClosing(WindowEvent e)

{

System.exit(0);

}

});

}

public static void main(String[] args)

{

new Traffic();

}

public void itemStateChanged(ItemEvent e)

{

clr=(e.getItem()).toString();

repaint();

}

public void paint(Graphics g)

{

g.drawString("Traffic signals",200,250);

g.drawOval(200,300,50,50);

g.drawOval(200,400,50,50);

g.drawOval(200,500,50,50);

g.drawRect(180,200,100,400);

if(clr.equals("red"))

{

g.setColor(Color.red);

g.fillOval(200,300,50,50);

}

if(clr.equals("green"))

{

g.setColor(Color.green);

g.fillOval(200,400,50,50);

}

if(clr.equals("yellow"))

{

g.setColor(Color.yellow);

g.fillOval(200,500,50,50);

}

}

}