Question

I’m updating a picture by using timer, but it causes fatal performance problem. Then I print logs and find out my timer runs faster rather than 1500.
So what’s the problem?

schedule at wrong rate:

startToDraw().353: System.currentTimeMillis() = 1332742387400
startToDraw().353: System.currentTimeMillis() = 1332742387410
startToDraw().353: System.currentTimeMillis() = 1332742387438
startToDraw().353: System.currentTimeMillis() = 1332742387449
startToDraw().353: System.currentTimeMillis() = 1332742387472

timer = new Timer();
timer.schedule(new TimerTask() {
    @Override
    public void run() {
        while (!isDestroyed) {
            try {
                Log.i(getClass().getName(), "startToDraw().353: System.currentTimeMillis() = " + System.currentTimeMillis());
                handler.sendMessage(new Message());
            } catch (Exception e) {
            }
        }
    }
}, 0, 1500);

Answer 1

I think the problem is that you are entering a while loop that runs repeatedly. You probably just want to make a check if you are in an invalid state and then if you are, don’t perform the task. So I would change:

while (!isDestroyed) {
    try {
        Log.i(getClass().getName(), "startToDraw().353: System.currentTimeMillis() = " + System.currentTimeMillis());
        handler.sendMessage(new Message());
    } catch (Exception e) {
}

to:

if (!isDestroyed) {
    try {
        Log.i(getClass().getName(), "startToDraw().353: System.currentTimeMillis() = " + System.currentTimeMillis());
        handler.sendMessage(new Message());
    } catch (Exception e) {
}