在 Recycler Adapter 中获取活动 onDestroy()

Question

I am using a Handler to display a timer in RecyclerView list item. When I press back the Activity that hosts the RecyclerView is completely destroyed, the Handler() still running in the background. The handler is created and initiated in ViewHolder . Is there any way to remove the callbacks from handler from ViewHolder itself?

My ViewHolder sample code

class ViewHolder(itemView: View) : RecyclerView.ViewHolder(itemView), CustomRunnable.CustomRunnableListener{

    private val handler = Handler()
    lateinit var customRunnable: CustomRunnable //custom runnable for my timer logic

    fun bind(position: Int, listModelClass: ModelClass?){


        if(someCondition){
                customRunnable = CustomRunnable(handler, this, textView, listModelClass)
                handler.postDelayed(customRunnable, 1000)
        }

    }

    override fun onTimerFinish(listModelClass: ModelClass) {
            // I get this call back when the timer finishes
            handler.removeCallbacks(customRunnable)
    }

}

Answer 1

As per my knowledge, there is no method on adapter that is called when RecyclerView is detached from activity.

Try creating a timer object or a list of objects in your BaseActivity or Application Class and after pressing onBack run a method that will stop that timer or timers.

//Declare timer
    CountDownTimer cTimer = null;

    //start timer function
    void startTimer() {
        cTimer = new CountDownTimer(30000, 1000) {
            public void onTick(long millisUntilFinished) {
            }
            public void onFinish() {
            }
        };
        cTimer.start();
    }


    //cancel timer
    void cancelTimer() {
        if(cTimer!=null)
            cTimer.cancel();
    }

Answer 2

You can do it onDestory() of activity

handler.removeCallbacksAndMessages(null);

Remove any pending posts of callbacks and sent messages whose obj is token. If token is null, all callbacks and messages will be removed.