CODEWITHSUNDEEP
javaandroid
ovniMode
ovniMode

Reputation: 35

Android - Trying to change the color of a bouncing ball every 3-5 seconds?

I'm new to android programming, right now for practice I'm trying to make an app where this ball bounces around the screen while changing from various colors such as red, green, blue, and yellow. So far I've managed to make the ball bounce but the issue I'm struggling with at the moment is having the ball change color every three or five seconds, this is so far what I have. This seems to work but only for the first time you start the activity after that it goes back to randomly changing colors without having to wait for three seconds to change, thanks and would appreciate any help.

@Override
protected void onDraw(Canvas canvas) {
    // TODO Auto-generated method stub
    ballBounds.set(ballX-ballRadius, ballY-ballRadius, ballX+ballRadius,ballY+ballRadius);
    Handler handler = new Handler();        
    int rnd = (int)(Math.random() * 4);
    switch(rnd){
    case 0:handler.postDelayed(new Runnable(){
        public void run(){
        paint.setColor(Color.BLUE);
        }
    }, 3000);
        break;
    case 1: handler.postDelayed(new Runnable(){
        public void run(){
        paint.setColor(Color.RED);
        }
    }, 3000);
        break;
    case 2: handler.postDelayed(new Runnable(){
        public void run(){
        paint.setColor(Color.GREEN);
        }
    }, 3000);
        break;
    case 3:handler.postDelayed(new Runnable(){
            public void run(){
            paint.setColor(Color.YELLOW);
            }
        }, 3000);
        break;
    }

    canvas.drawOval(ballBounds, paint);

Upvotes: 0

Views: 276

Answers (2)

Tejas
Tejas

Reputation: 585

Try something like this :

@Override
protected void onDraw(Canvas canvas) {
    // TODO Auto-generated method stub
    ballBounds.set(ballX-ballRadius, ballY-ballRadius, ballX+ballRadius,ballY+ballRadius);

canvas.drawOval(ballBounds, paint);
}

public void startLoading(){
    task = new TimerTask() {

        @Override
        public void run() {

            int rnd = (int)(Math.random() * 4);
            switch(rnd){
            case 0:
                paint.setColor(Color.BLUE);
                break;
            case 1: 
                paint.setColor(Color.RED);
                break;
            case 2: 
                paint.setColor(Color.GREEN);
                break;
            case 3:
                paint.setColor(Color.YELLOW);
                break;
            }
            postInvalidate();
        }

    };
    timer = new Timer();
    timer.schedule(task, 0, 3000);

}

Upvotes: 0

LuigiEdlCarno
LuigiEdlCarno

Reputation: 2415

Your problem is, that you start color changing in the onDraw. Everytime the ball is redrawn a new Runnable is added to the message queue. Each Runnable will only be executed after 3 seconds since it was added to the queue, but not since the message before it was executed.

That is why you get the delay, when you sart te activity, but then see quicker changes.

You could create acolor changing thread the has a build in delay between each new color calculation, though. That way you get the delay you want.

Upvotes: 1

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