Android schedule fast task

Question

I have a problem with events schedulation. I need to change text color every fixed time. Range of this is between 100ms and 300ms. I've tried to use Android Timer - TimerTask but after 10-15 Thread the rendering is delayed then I lost real time update. I've tried also to use Thread.sleep() but I've had an exception with MainThreadActivity. Timer problem I think that is JVM Thread allocation or at most a concurrency problem. I asked you what is the best way for scheduling fast event with fixed delay in Android and if my approach is correct.

Thank you in advance.

Fabio

Answer 1

Try something like this:

final static int REFRESH_TIME_MS = 100;
final static int REFRESH_TIME_MS_2 = 200;

Runnable mPeriodicTask = new Runnable() {
    public void run() {
        //do what you want
    }
};

Runnable mPeriodicTask_2 = new Runnable() {
    public void run() {
        //do what you want
    }
};

@Override
public void onCreate(Bundle savedInstanceState) {
    ScheduledExecutorService executor = Executors.newScheduledThreadPool(2);
    executor.scheduleAtFixedRate(mPeriodicTask, 0, REFRESH_TIME_MS, TimeUnit.MILLISECONDS);
    executor.scheduleAtFixedRate(mPeriodicTask_2, 0, REFRESH_TIME_MS_2, TimeUnit.MILLISECONDS);
}

Answer 2

Try the CountDownTimer. It's executed on the UI Thread and gives you information on exactly how much time passed since the last invocation. Adding an example to be more clear: Let's say you want to update the view after 300 ms ,150 ms and 75 ms that makes the total time 525ms and the minimum interval 50ms

so:

    private class TestCT extends CountDownTimer{

            private long mFirstTime;
            private long mTotalTime;
            private long mLastRecognizedEvent=0;

            public TestCT(long millisInFuture, long countDownInterval, long firstEventTime) {
                super(millisInFuture, countDownInterval);
                mTotalTime=millisInFuture;
                mFirstTime=firstEventTime;
            }

            @Override
            public void onTick(long millisUntilFinished) {
                long elapsed=mTotalTime-millisUntilFinished;
                elapsed-=mLastRecognizedEvent;
                if(elapsed>=mFirstTime){
                    updateTheView();
                    mLastRecognizedEvent+=mFirstTime;
                    mFirstTime=mFirstTime/2;
                }
            }

            @Override
            public void onFinish() {
                updateTheView();

            }


        }

new TestCT(525,50,300).start();

Not tested this so not 100% sure will work but it should give you an idea