How to run a method every X seconds

I'm developing an Android 2.3.3 application and I need to run a method every X seconds.

In iOS, I have NSTimer, but in Android I don't know what to use.

Someone have recommend me Handler; another recommend me AlarmManager but I don't know which method fits better with NSTimer.

This is the code I want to implement in Android:

timer2 = [
    NSTimer scheduledTimerWithTimeInterval:(1.0f/20.0f)
    target:self
    selector:@selector(loopTask)
    userInfo:nil
    repeats:YES
];

timer1 = [
    NSTimer scheduledTimerWithTimeInterval:(1.0f/4.0f)
    target:self
    selector:@selector(isFree)
    userInfo:nil
    repeats:YES
];

I need something what works like NSTimer.

What do you recommend me?

The solution you will use really depends on how long you need to wait between each execution of your function.

If you are waiting for longer than 10 minutes, I would suggest using AlarmManager.

// Some time when you want to run
Date when = new Date(System.currentTimeMillis());

try {
	Intent someIntent = new Intent(someContext, MyReceiver.class); // intent to be launched

	// Note: this could be getActivity if you want to launch an activity
	PendingIntent pendingIntent = PendingIntent.getBroadcast(
		context,
		0, // id (optional)
		someIntent, // intent to launch
		PendingIntent.FLAG_CANCEL_CURRENT // PendingIntent flag
	);

	AlarmManager alarms = (AlarmManager) context.getSystemService(
		Context.ALARM_SERVICE
	);

	alarms.setRepeating(
		AlarmManager.RTC_WAKEUP,
		when.getTime(),
		AlarmManager.INTERVAL_FIFTEEN_MINUTES,
		pendingIntent
	);
} catch(Exception e) {
	e.printStackTrace();
}

Once you have broadcasted the above Intent, you can receive your Intent by implementing a BroadcastReceiver. Note that this will need to be registered either in your application manifest or via the context.registerReceiver(receiver, intentFilter); method. For more information on BroadcastReceiver's please refer to the official documentation..

public class MyReceiver extends BroadcastReceiver {
	@Override
	public void onReceive(Context context, Intent intent)
	{
		System.out.println("MyReceiver: here!") // Do your work here
	}
}

If you are waiting for shorter than 10 minutes then I would suggest using a Handler.

final Handler handler = new Handler();
final int delay = 1000; // 1000 milliseconds == 1 second

handler.postDelayed(new Runnable() {
	public void run() {
		System.out.println("myHandler: here!"); // Do your work here
		handler.postDelayed(this, delay);
	}
}, delay);

Use Timer for every second...

new Timer().scheduleAtFixedRate(new TimerTask() {
	@Override
	public void run() {
        //your method
    }
}, 0, 1000);//put here time 1000 milliseconds=1 second

You can please try this code to call the handler every 15 seconds via onResume() and stop it when the activity is not visible, via onPause().

Handler handler = new Handler();
Runnable runnable;
int delay = 15*1000; //Delay for 15 seconds.  One second = 1000 milliseconds.


@Override
protected void onResume() {
   //start handler as activity become visible

    handler.postDelayed( runnable = new Runnable() {
        public void run() {
            //do something
           
            handler.postDelayed(runnable, delay);
        }
    }, delay);

    super.onResume();
}

// If onPause() is not included the threads will double up when you 
// reload the activity 

@Override
protected void onPause() {
    handler.removeCallbacks(runnable); //stop handler when activity not visible
    super.onPause();
}



    

If you are familiar with RxJava, you can use Observable.interval(), which is pretty neat.

Observable.interval(60, TimeUnits.SECONDS)
          .flatMap(new Function<Long, ObservableSource<String>>() {
                @Override
                public ObservableSource<String> apply(@NonNull Long aLong) throws Exception {
                    return getDataObservable(); //Where you pull your data
                }
            });

The downside of this is that you have to architect polling your data in a different way. However, there are a lot of benefits to the Reactive Programming way:

1. Instead of controlling your data via a callback, you create a stream of data that you subscribe to. This separates the concern of "polling data" logic and "populating UI with your data" logic so that you do not mix your "data source" code and your UI code.

2. With RxAndroid, you can handle threads in just 2 lines of code.

   Observable.interval(60, TimeUnits.SECONDS)
         .flatMap(...) // polling data code
         .subscribeOn(Schedulers.newThread()) // poll data on a background thread
         .observeOn(AndroidSchedulers.mainThread()) // populate UI on main thread
         .subscribe(...); // your UI code
   

Please check out RxJava. It has a high learning curve but it will make handling asynchronous calls in Android so much easier and cleaner.

With Kotlin, we can now make a generic function for this!

object RepeatHelper {
    fun repeatDelayed(delay: Long, todo: () -> Unit) {
	    val handler = Handler()
	    handler.postDelayed(object : Runnable {
		    override fun run() {
			    todo()
			    handler.postDelayed(this, delay)
		    }
	    }, delay)
    }
}

And to use, just do:

val delay = 1000L
RepeatHelper.repeatDelayed(delay) {
	myRepeatedFunction()
}

    new CountDownTimer(120000, 1000) {

        public void onTick(long millisUntilFinished) {
            txtcounter.setText(" " + millisUntilFinished / 1000);
            
        }

        public void onFinish() {
        
            txtcounter.setText(" TimeOut  ");
            Main2Activity.ShowPayment = false;
            EventBus.getDefault().post("go-main");

        }

    }.start();

Here I used a thread in onCreate() an Activity repeatly, timer does not allow everything in some cases Thread is the solution

     Thread t = new Thread() {
        @Override
        public void run() {
            while (!isInterrupted()) {
                try {
                    Thread.sleep(10000);  //1000ms = 1 sec
                    runOnUiThread(new Runnable() {
                        @Override
                        public void run() {

                            SharedPreferences mPrefs = getSharedPreferences("sam", MODE_PRIVATE);
                            Gson gson = new Gson();
                            String json = mPrefs.getString("chat_list", "");
                            GelenMesajlar model = gson.fromJson(json, GelenMesajlar.class);
                            String sam = "";

                            ChatAdapter adapter = new ChatAdapter(Chat.this, model.getData());
                            listview.setAdapter(adapter);
                           // listview.setStackFromBottom(true);
                          //  Util.showMessage(Chat.this,"Merhabalar");
                        }
                    });

                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
            }
        }
    };

    t.start();

In case it needed it can be stoped by

@Override
protected void onDestroy() {
    super.onDestroy();
    Thread.interrupted();
    //t.interrupted();
}

I do it this way and it works fine (the code is written in Kotlin):

private lateinit var runnable: Runnable

private var handler = Handler(Looper.getMainLooper())

private val repeatPeriod: Long = 10000

Then reinit the runnable from inside your function

runnable = Runnable {

    // Your code goes here

    handler.postDelayed(runnable, repeatPeriod)

}

handler.postDelayed(runnable, repeatPeriod)

Note that if you don't postDelay twice the handler, the loop is not going to be intinity!

In Kotlin, you can do it this way with a Runnable:

private lateinit var runnable: Runnable
private var handler = Handler(Looper.getMainLooper())
private val interval: Long = 1000
private var isRunning = false

val runnable = object : Runnable {
    override fun run() {
        // Do something every second
        function()
        // Call your runnable again after interval
      handler?.postDelayed(runnable(this, interval))
    }
}
    
// Call your function once
if (!isRunning) {
    handler?.postDelayed(runnable, interval)
    isRunning = true
}

// Remove your repeatedly called function
if (isRunning) {
    handler?.removeCallbacks(runnable)
    isRunning = false
}