Is this a prefect way to stop handlerthread?

Question

I always create two handler: one is wraping on main thread, another is wraping on a single thread.

Is this a best method to start and stop these in an Activity lifecycle?

HandlerThread safeThread = null;
Handler safeHandler = null;
Handler handler = null;


@Override
    public void onStart() {

if (safeThread == null) {
            safeThread = new HandlerThread("safeThread");
            safeThread.start();
            safeHandler = new Handler(safeThread.getLooper());
        } else if (safeThread.getState() == Thread.State.NEW) {
            safeThread.start();
            safeHandler = new Handler(safeThread.getLooper());
        } else if (safeThread.getState() == Thread.State.WAITING) {
            safeHandler = new Handler(safeThread.getLooper());
        } else if (safeThread.getState() == Thread.State.TERMINATED) {
            safeThread = null;
            safeThread = new HandlerThread("safeThread");
            safeThread.start();
            safeHandler = new Handler(safeThread.getLooper());
        }
}




protected void onStop() {
        Log.d("x", "onStop is executed");
        safeHandler = null;
        safeThread.quit();
        safeThread.interrupt();
        safeThread = null;
        super.onStop();
    }

yes , i know but i thinking about is this safe when i after interrupt and null this. — rex, Jan 18 '12 at 09:37
i have given answer..one thing i would suggest you as you are new on stackoverflow.IF you want to appreciate someone help then give him a vote and if you think answer is best then mark it as answer..:) welcome and cheers — Tofeeq Ahmad, Jan 18 '12 at 09:42

score 25 · Answer 1 · answered Mar 04 '14 at 14:21

25

I know it's a somewhat old question, but I stumble across it looking for the same answer and further researching I don't believe the current answer applies very well to HandlerThread (although absolutely correct for normal threads)

HandlerThread have a builtin quit() and quitSafely(API18) methods to stop the thread. https://developer.android.com/reference/android/os/HandlerThread.html#quit()

the difference between the two is only if the messages in queue will be processed before it stops or not.

so to answer, it's as simple as:

safeThread.quit();

answered Mar 04 '14 at 14:21

Budius

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To add clarity: quit() is available in API 5 – Vyrx Jul 30 '15 at 13:43
2

What to do before api 18? – JohnyTex Feb 16 '16 at 11:14
1

Does quit() or quitSafely() stops Thread or only the Looper that thread has to handle messages? It does not explain if it ends thread or not [here](https://developer.android.com/reference/android/os/HandlerThread.html#quit()). – Thracian Oct 17 '17 at 15:01
@Thracian the looper is a for-loop cycle that runs in `HandlerThread#run()` method forever. This prevents the `run()` method from reaching the end, thus keeping the `Thread` alive. The `Thread` is terminated right after the looper is quit. – Max_Payne Apr 14 '23 at 08:36

SharkAlley · Answer 2 · 2015-09-29T20:49:53.253

17

If you start the thread like this:

HandlerThread thread = new HandlerThread("MyHandlerThread");
thread.start();

The safest way to stop it would be:

thread.quitSafely();

quitSafely ensures that all pending messages are processed before the thread stops.

Note: My original answer included an additional call to thread.join, but I found the join call does not release reliably when used after quitSafely.

edited Sep 29 '15 at 20:49

answered Aug 11 '15 at 20:24

SharkAlley

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I'm also wondering whether I need to join after quitSafely. Can you clarify "does not release reliably"? Thanks! – Kaifei Feb 02 '16 at 22:53
@Kaifei I recall I was observing that the join call just blocks the thread. That was back in August, so not 100% sure. – SharkAlley Feb 03 '16 at 00:34
quitSafely was key. Thanks – Shubham AgaRwal May 05 '18 at 15:14

Tofeeq Ahmad · Accepted Answer · 2020-02-03T06:10:51.727

1

You can use this as a safe way to stop threads:

 if (safeThread!= null) {
     safeThread.quit();
     safeThread = null; // Object is no more required.
 }

You can use safeThread.quitsafely as well.

edited Feb 03 '20 at 06:10

answered Jan 18 '12 at 09:40

Tofeeq Ahmad

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For more details see this http://stackoverflow.com/questions/680180/where-to-stop-destroy-threads-in-android-service-class – Tofeeq Ahmad Jan 18 '12 at 09:43
2

can you explain more details ?? what the reason ?? – rex Jan 18 '12 at 10:12
For Reason see question in my above comment – Tofeeq Ahmad Jan 18 '12 at 10:13
The question was about `HandlerThread`. This response is about `Thread`. If the `Handler` part isn't important, this answer needs to note that, and explain why. – Jameson Apr 10 '20 at 05:27

score 0 · Answer 4 · answered Mar 25 '19 at 12:07

0

I have been following this :

if (safeHandler!= null) {
     final Looper looper = safeHandler.getLooper();
     looper.quitSafely();
     safeHandler = null;
 }

answered Mar 25 '19 at 12:07

iammrmehul

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Is this a prefect way to stop handlerthread?

4 Answers4

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