Incremental Timer

Question

I'm currently using a Timer and TimerTask to perform some work every 30 seconds.

My problem is that after each time I do this work I want to increment the interval time of the Timer.

So for example it starts off with 30 seconds between the timer firing but I want to add 10 seconds to the interval then so that the next time the Timer takes 40 seconds before it fires.

Here is my previous code:

---

  public void StartScanning() {

    scanTask = new TimerTask() {
        public void run() {
                handler.post(new Runnable() {
                        public void run() {

                            wifiManager.startScan();
                            scanCount++;            
                            if(SCAN_INTERVAL_TIME <= SCAN_MAX_INTERVAL){

                                SCAN_INTERVAL_TIME = SCAN_INTERVAL_TIME + SCAN_INCREASE_INTERVAL;
                                t.schedule(scanTask, 0, SCAN_INTERVAL_TIME);
                            }

                        }
               });
        }};
        Log.d("SCAN_INTERVAL_TIME ** ", "SCAN_INTERVAL_TIME ** = " + SCAN_INTERVAL_TIME);
        t.schedule(scanTask, 0, SCAN_INTERVAL_TIME);

}

---

REFACTORED CODE

---

@Override
public void StartScanning() {

        t.schedule(new ScanTask(),SCAN_INTERVAL_TIME);

}

class ScanTask extends TimerTask{

    @Override
    public void run() {
        wifiManager.startScan();
        scanCount++;   

        if(SCAN_INTERVAL_TIME < SCAN_MAX_INTERVAL)
        SCAN_INTERVAL_TIME = SCAN_INTERVAL_TIME + SCAN_INCREASE_INTERVAL;

        t.schedule(new ScanTask(), SCAN_INTERVAL_TIME);
    }


}

It works now but is creating a new ScanTask() every time wasteful?

Answer 1

Here is how I would do it:

1) Schedule the task for a single execution rather than a repeated one

2) At the end of the execution (possibly in a finally block), schedule a new single execution of the task, with a longer delay. Note that you must create a new instance of the task, otherwise the timer will complain (IllegalStateException). That means that you can't use an anonymous inner class anymore.