Write a java program that simulates a traffic light. The program lets the user select one of three lights: red, yellow, or green with radio buttons. On selecting a button, an appropriate message with “stop” or “ready” or “go” should appear above the buttons in a selected color. Initially, there is no message shown.
Program Code:
TrafficSignal.java
import java.awt.*;
import java.applet.*;
import java.awt.event.*;
public class TrafficSignal extends Applet implements Runnable
{
Thread t;
Font f, f1;
int i = 0, a = 0, j = 0;
public void init()
{
setBackground(Color.lightGray);
f = new Font("TimesNewRoman", f.ITALIC, 28);
f1 = new Font("TimesNewRoman", Font.ITALIC + Font.BOLD, 28);
}
public void start()
{
t = new Thread(this);
t.start();
}
public void run()
{
for (i = 10; i >= 0; i--)//countdown
{
try
{
Thread.sleep(1000);
}
catch (Exception e)
{
System.out.println(e);
}
if (i <= 10 && i > 3)//red
{
a = 1;
repaint();
}
else if (i <= 3 && i > 0)//yellow
{
a = 2;
repaint();
}
else if (i == 0)//green
{
for (j = 0; j < 10; j++)
{
a = 3;
try
{
Thread.sleep(1000);
}
catch (Exception e)
{
System.out.println(e);
}
repaint();
}
if (j == 10)//end of green(return to red)
{
run();
}
}
}
repaint();
}
public void paint(Graphics g)
{
setBackground(Color.lightGray);//ROAD
g.setColor(Color.black);//POLE UP
g.fillRect(150, 150, 50, 150);
g.drawRect(150, 150, 50, 150);
g.setColor(Color.black);//POLE DOWN
g.fillRect(165, 300, 20, 155);
g.drawRect(165, 300, 20, 155);
g.drawOval(150, 150, 50, 50);//RED
g.drawOval(150, 200, 50, 50);//YELLOW
g.drawOval(150, 250, 50, 50);//GREEN
g.setColor(Color.red);//COUNTDOWN STOP
g.setFont(f);
g.drawString("" + i, 50, 50);
if (a == 1)//REDSIGNAL
{
g.setColor(Color.red);
g.fillOval(150, 150, 50, 50);
g.drawOval(150, 150, 50, 50);
g.drawString("STOP", 50, 150);
}
if (a == 2)//YELLOWSIGNAL
{
g.setColor(Color.yellow);
g.fillOval(150, 200, 50, 50);
g.drawOval(150, 200, 50, 50);
g.drawString("READY", 50, 200);
}
if (a == 3)//GREENSIGNAL
{
g.setColor(Color.blue);//countdown
g.setFont(f);
g.drawString("" + j, 150, 50);
g.setColor(Color.green);
g.fillOval(150, 250, 50, 50);
g.drawOval(150, 250, 50, 50);
g.drawString("GO", 50, 250);
}
int x1[] = {220, 300, 300, 280};
int y1[] = {250, 150, 250, 150};
int n1 = 4;
int n2 = 3;
int x2[] = {340, 380, 380};
int y2[] = {150, 100, 150};
int x3[] = {460, 460, 500};
int y3[] = {150, 100, 150};
}
}
TrafficSignal.html
<html>
<head>
</head>
<body>
/*<applet code="TrafficSignal.class" height=500 width=300></applet>*/
</body>
</html>
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