How to Start Timer from One Activity and Stop from another activity?

Question

I want to start a Timer from a class which will keep on running until i stop from it from other class. For this, I have created class for timer and methods named startTimer and stopTimer as given below:

public class TimerTaskClass extends Application {
Timer timer = new Timer();

public static final int TIME_INTERVAL = 10000;

public void startTimer(final Context context) {

    Log.d("Constants", "Timer Started");
        timer.scheduleAtFixedRate(new java.util.TimerTask() {

            @SuppressLint("DefaultLocale")
            @Override
            public void run() {

             //Performing my Operations

            }
        }, 0, TIME_INTERVAL);

}



public void stopTimer() {
    timer.cancel();
}

What i am doing is, I have two activity ClassA and ClassB

 Class A{

  onCreate(){
     TimerTaskClass tmClass=new TimerTaskClass();
     tmClass.startTimer();
  }


 }

  Class B{

  onCreate(){
     TimerTaskClass tmClass=new TimerTaskClass();
     tmClass.stopTimer();
  }


 }

But this is not stopping my timer which i have started from ClassA. How this can be done?

@Shane Ty for replying. But i have Activity and changing it to fragment will be a big change for me. :(. Any Other way to do so? — Rahul Verma, Oct 20 '16 at 10:30
Why do you let TimerTaskClass extend Application? Did you also make the necessary changes in the Manifest to really use it as *the* Application (set `android:name` attribute)? — Bö macht Blau, Oct 20 '16 at 10:37
@0X0nosugar no i didnt did anything in manifest. I did this by reading somewhere, so that this remains same in whole application. — Rahul Verma, Oct 20 '16 at 10:44
But to make use of TimerTaskClass as your application class you need to change the Manifest. If you do so, you can access the same timer instance from every Activity. — Bö macht Blau, Oct 20 '16 at 10:46

score 2 · Accepted Answer · answered Oct 20 '16 at 10:36

2

Maybe you could change TimerTaskClass to singleton, so in both activities you will use the same instance of TimerTaskClass, it should solve your problem.

public class TimerTaskClass 
{
    private static TimerTaskClass _instance;

    private TimerTaskClass ()
    {

    }

    public synchronized static TimerTaskClass getInstance()
    {
        if (_instance == null)
        {
            _instance = new TimerTaskClass ();
        }
        return _instance;
    }
}

answered Oct 20 '16 at 10:36

Thror

437
4
4

I am trying this.Ty for replying. – Rahul Verma Oct 20 '16 at 10:44
i think its a wise solution!!! because he need the same instance while he was creating separate instance for start and stop function!!! – Nowshad Oct 20 '16 at 10:52

score 1 · Answer 2 · answered Oct 20 '16 at 11:03

Your TimerTaskClass extends Application. This is possible although it may not the best solution in every case, see the documentation. To follow through with this approach, you also have to set the android:name attribute for application in the Manifest.xml:

<application
    android:name=".TimerTaskClass"
    ...keep the rest like before...
>
    ... keep this part unchanged as well ...
</application>

Now, TimerTaskClass will be instanciated as soon as your app is launched.

You can access it from every Activity like this:

TimerTaskClass ttc = (TimerTaskClass)getApplication();

The timer will be created as member of the Application instance (which is a Singleton by default), so there will only be one instance of it. So you can start it as follows:

ttc.startTimer(getApplicationContext());

If you decide that using your own Application object is not what you want, I think the answer by @Thror will be the best way to go. BTW in this case, you certainly should not let TimerTaskClass inherit from Application - it would not be useful and might even cause problems.

Thanx for letting me know the differences. And i have adopted Thror solutions. — Rahul Verma, Oct 20 '16 at 11:07
@Rahul - I think that's indeed the best option here. Please don't forget to accept Thror's answer (click grey checkmark below votes). — Bö macht Blau, Oct 20 '16 at 11:10

score 0 · Answer 3 · edited May 23 '17 at 12:33

The problem is that Activity A and Activity B each create their own TimerTaskClass instance. Instead, they should share an instance.

The easiest way to do this is to implement the TimerTaskClass as a Singleton so that both activities can talk to the same instance of the class.

Beware that overuse of the Singleton pattern leads to bugs that can be hard to trace and fix. As long as there aren't many components invoking methods on your singleton at the same time, you should be safe.

score 0 · Answer 4 · answered Oct 20 '16 at 10:45

For this you have to create singleton as below

public class TimerTaskClass {
    Timer timer = new Timer();
    public static final int TIME_INTERVAL = 10000;

  public void startTimer(final Context context) {

   Log.d("Constants", "Timer Started");
    timer.scheduleAtFixedRate(new java.util.TimerTask() {

        @SuppressLint("DefaultLocale")
        @Override
        public void run() {

         //Performing my Operations

        }
    }, 0, TIME_INTERVAL);

  }
public void stopTimer() {
  timer.cancel();
}

Now in Activity you have to do this

TimerTaskClass tmClass=new TimerTaskClass();
tmClass.startTimer();

And in Second Activity

 TimerTaskClass tmClass=new TimerTaskClass();
 tmClass.stopTimer();

Hope you understand the concept

How to Start Timer from One Activity and Stop from another activity?

4 Answers4