lenamuit/observer_timer.md

## observer_timer.md

      
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              observer_timer.md
            
          
    In the pass, to build the timer task, for example: to show count down timer on TextView or show current position when play the music or video use MediaPlayer, I use TimerTask or Timer object as the best choices.
This is the old source code
timer = new Timer();
timer.scheduleAtFixedRate(new TimerTask() {
    @Override 
    public void run() { 
        runOnUiThread(new Runnable() {
            @Override 
            public void run() { 
                if (isTrue()) { 
                    tv.post(new Runnable() {
                        @Override 
                        public void run() { 
                            tv.setText(getTimerText()); 
                        } 
                    }); 
                } 
            } 
        }); 
    } 
}, 0, 1000); 
**Above solution is rarely basically, It's not good in some cases. **
Now, I will show you how to solve above task with rxjava

int mSickTimer = 0;
//build the Observable object
final Observable<Integer> timerObservable = Observable.create(new Observable.OnSubscribe<Integer>() {
  @Override
  public void call(Subscriber<? super Integer> subscriber) {
      subscriber.onStart();
      while (isTrue()) {
          subscriber.onNext(mSickTimer ++);
          try {
              Thread.sleep(1000);
          } catch (InterruptedException e) {
              subscriber.onCompleted();
          }
      }
      subscriber.onCompleted();
  }
});
//Excute the observable by call *subscribe*, 
// Key features here, you can control what thread excute timer and handle callback. 
timerObservable.subscribeOn(Schedulers.io())
    .observeOn(AndroidSchedulers.mainThread())
    .subscribe(timerObserver);
    
//timerObserver
timerObserver = new Observer<Integer>() {
            @Override
            public void onCompleted() {
                //complete timer
            }

            @Override
            public void onError(Throwable e) {
                //error -> I will make it finish here
            }

            @Override
            public void onNext(Integer i) {
                updateTimer(i);
            }
        }
If you're interested with RxJava, you can try and give me your opinion.
Thanks!