Change color randomly of object

Question

Hi,
I wrote a small application simulating a road traffic. I am using threads to do the animation.
this is the code:
public class TestProject extends Frame implements Runnable
   public static int frame;   // int variable for frame (animation)
    int delay = 100;    // delay for animation
    Thread animator, light;    // thread name
     * Create a thread and start it.
    public void start()
        animator = new Thread(this);    // create new thread
        animator.start();               // start thread
     * This method is called by the thread that was created in
     * the start method. It does the main animation.
    public void run()
        // Remember the starting time
        long tm = System.currentTimeMillis();   // get time (ms) and store it in tm
        while (Thread.currentThread() == animator)
            // Display the next frame of animation.
            if (frame==(200*roadArrangement.size()+50)) // if object reaches "end" reset
                frame =-50; // "reset" frame
            repaint();  // repaint object
            // Delay depending on how far we are behind.
            try
                tm += delay;    // delay
                Thread.sleep(Math.max(0, tm - System.currentTimeMillis()));
            catch (InterruptedException e) // catch exception for thread
                System.out.println("error in thread interrupt!");
                break;
            frame++;    // Advance the frame
    } // end of run
     * Set the animator variable to null so that the
     * thread will exit before displaying the next frame.
    public void stop()
        animator = null;
     * Paint a frame of animation.
    public void paint(Graphics g)
        for(int i = 0; i < roadArrangement.size(); i++)
            String tempType = roadArrangement.elementAt(i).toString();
            char roadType = tempType.charAt(0);
            g.setColor(Color.darkGray);
            if(roadType == 'r')
                g.setColor(Color.darkGray);
                g.fill3DRect(10+(i*210),100,210,60,true);
            else if(roadType == 'j')
                g.setColor(Color.darkGray);
                g.fill3DRect(10+(i*210),100,210,60,true);
                g.fill3DRect(85+(i*210),160,60,70,true);
                g.fill3DRect(85+(i*210),30,60,70,true);
                g.setColor(Color.green); // traffic light color
                g.fillOval(10+(i*210)+50,30+100,10,10); // traffic light
                Color clr = g.getColor();
                int red = clr.getRed();
                if((frame == (10+(i*210)+50))&&(red==255))
                    stop(); // stop thread to stop cars
                    System.out.println("STOP");  
}In the code I have "oval" traffic lights where I set the colours.
Now, what I want to do is that traffic lights change independently and randomly their colour so that cars stop and drive.
How can I do this? Will I need a second thread? If yes, how to implement that?
thanks in advance.

Answer 1

Use [url http://java.sun.com/j2se/1.5.0/docs/api/java/util/Random.html]Random class and call nextInt every time in paint method than match a color to the int you get back.