Question

I have a problem with this code used for Android (Java)

handler.postDelayed(new Runnable(){
public void run(){
    // Your code goes here...
}
}, 500);

If the delay is about 500ms then the program seems to repeat the task at 0.5s, but if I change to less than 100ms or even less it does not follow any more. I test the brightness change and for a while it can repeat the change of brightness at that rate, but then slow down and come back to normal flash rate again. It seems unstable. Do you have any code that give exact delay regardless of the load of the phone’s CPU.

Many thanks

Answer 1

You might be able to do something more precise if you use a CountDownTimer which has a periodic tick. Essentially you set it to count down for a period which can be hours if need be, and there are two methods one method is called on each tick, and the other at the end of the timer at which point you could start another one. Anyway you could set the tick to be very fast, and then only kick off the code at the delay point by check the actual time difference in the click. I think thats about the best you could do. Essentially inside the tick you would issue a signal if the right amout of time had actually passed. That signal would either kick off the thread or release something the already running thread was waiting on. What is the value of the CountDownTimer, I guess its just that you can do a very frequent polling, and elapsed time check. Although its not guaranteed, the time between the ticks you can set it to a high frequency and check/poll very frequently. This could lead to a smooth performance not unlike a realtime system. Its more likely to be accurate because its just issuing a signal and not taking up the resources of threading just to issue the signal. You might also try an IntentService to perform the tasks and just call startService(intentToIntentService) each call. See if the threading works better inside a service like IntentService which does queue them up I believe.

 Date startDate = new Date();
 long startTime = startDate.getTime();
 // Tick called every 10th of a second.  OnFinish called at Signal.
 CountDownTimer ctDownTimer = new CountDownTimer(30000, 100) {
 long startIntervalTime=startTime;
 public void onTick(long millisUntilFinished) {

     Date now = new Date();
     long nowTime = now.getTime();
     if ((startIntervalTime - nowTime) > 100)
     {
        issueSignal();
        intervalStartTime=nowTime;
     }
     now=null;
 }

 public void onFinish() {
     Log.d("MyClass", "Done")  // Maybe start out.
 }
}.start();