Toast created in an IntentService never goes away

Question

I have an IntentService that downloads some files. The problem is that I create a Toast inside the IntentService like this

Toast.makeText(getApplicationContext(), "some message", Toast.LENGTH_SHORT).show();

The Toast will never disappear event if I exit the app. The only way to destroy it is to kill the process.

What am I doing wrong?

There's no reason not to create a Toast from a service. From [the notification dev guide](http://developer.android.com/guide/topics/ui/notifiers/toasts.html): >If you create a toast notification from a Service, it appears in front of the Activity currently in focus. — Pierre-Luc Paour, Oct 11 '10 at 12:06
That must be wrong, because it doesn't work when you test it with IntentService. @rony's solution works best. — IgorGanapolsky, Oct 04 '12 at 15:19

score 75 · Answer 1 · edited Jul 29 '13 at 13:28

75

The problem is that IntentService is not running on the main application thread. you need to obtain a Handler for the main thread (in onCreate()) and post the Toast to it as a Runnable.

the following code should do the trick:

@Override
public void onCreate() {
    super.onCreate();
    mHandler = new Handler();
}

@Override
protected void onHandleIntent(Intent intent) {
    mHandler.post(new Runnable() {            
        @Override
        public void run() {
            Toast.makeText(MyIntentService.this, "Hello Toast!", Toast.LENGTH_LONG).show();                
        }
    });
}

edited Jul 29 '13 at 13:28

maysi

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answered Mar 24 '11 at 14:43

rony l

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@rkmax android studio for some reason defaults to `import java.util.logging.Handler;` (which is abstract) change it to `import android.os.Handler;` – chacham15 Jul 22 '14 at 03:33
@rony If I call this from JNI I get a null pointer exception, any idea why that is? Do I need a new thread in JNI? – Stephan GM Jul 04 '16 at 18:08
Is new Handler() call expensive? – JohnyTex Sep 01 '17 at 06:32

score 24 · Answer 2 · edited Jun 18 '17 at 04:19

24

This works for me:

public void ShowToastInIntentService(final String sText) {
    final Context MyContext = this;

    new Handler(Looper.getMainLooper()).post(new Runnable() {
        @Override
        public void run() {
            Toast toast1 = Toast.makeText(MyContext, sText, Toast.LENGTH_LONG);
            toast1.show();
        }
    });
};

edited Jun 18 '17 at 04:19

Daniel

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answered Aug 13 '13 at 16:48

Ton

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Perfect solution – bdevay Sep 18 '19 at 21:02

score 8 · Answer 3 · answered May 27 '13 at 03:59

8

IntentService will create a thread to handle the new intent, and terminated it immediately once the task has done. So, the Toast will be out of controlled by a dead thread.

You should see some exceptions in the console when the toast showing on the screen.

answered May 27 '13 at 03:59

bluesway

107
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3

+1 for pointing out worker thread mechanism in IntentService. – Hai Zhang Aug 30 '14 at 04:26

score 1 · Answer 4 · edited Feb 13 '16 at 10:26

1

For people developing in Xamarin studio, this is how its done there:

Handler handler = new Handler ();
handler.Post (() => {
    Toast.MakeText (_Context, "Your text here.", ToastLength.Short).Show ();
});

edited Feb 13 '16 at 10:26

Ciro Santilli OurBigBook.com

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answered Dec 02 '14 at 06:18

Bugs Happen

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score 0 · Answer 5 · edited May 23 '17 at 12:02

To show a toast when the user is in one of the application activity.

Just need a reference of the current activity, and call it with this sample code:

public void showToast(final String msg) {
    final Activity a = currentActivity;
    if (a != null ) {
        a.runOnUiThread(new Runnable() {

            @Override
            public void run() {
                Toast.makeText(a, msg, Toast.LENGTH_SHORT).show();
            }
        });
    }
}

There is a lot of options to get the current activity, check this question: How to get current foreground activity context in android?

But I use this approach:

The application must have:

private Activity currentActivity = null;

public Activity getCurrentActivity() {
    return currentActivity;
}

public void setCurrentActivity(Activity mCurrentActivity) {
    this.currentActivity = mCurrentActivity;
}

Each activity must have:

@Override
protected void onResume() {
    super.onResume();
    ((MyApplication) getApplication()).setCurrentActivity(this);

}
@Override
protected void onPause() {
    super.onPause();
    ((MyApplication) getApplication()).setCurrentActivity(null);
}

Call `super.onPause()` from `onPause` – TWiStErRob Aug 13 '14 at 21:29 — TWiStErRob, Aug 13 '14 at 21:29
Oh my god a bug!... But it's gone now. – Daniel De León Aug 14 '14 at 08:24 — Daniel De León, Aug 14 '14 at 08:24

score -9 · Accepted Answer · answered Jul 21 '10 at 22:15

-9

You shouldn't create Toasts from a Service. You should use a Notification instead.

answered Jul 21 '10 at 22:15

Rich Schuler

41,814
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13

Wrong. from http://developer.android.com/guide/topics/ui/notifiers/toasts.html "A toast can be created and displayed from an Activity or Service". Its not working because "Service" runs on Main thread, whereas "Intent service" run on another thread. – Palani Oct 20 '11 at 10:43
6

Just because you can do a thing doesn't mean you should do a thing. You shouldn't create toasts from a service. – Rich Schuler Oct 26 '11 at 07:47
@Qberticus, can you update your answer with a code example of how Notification would be used in this case? – ban-geoengineering May 09 '14 at 17:33
1

Why should we use `Notification`s instead of `Toast`s from services? Is it because of a technical limitation? Is it because the user mightn't be looking at the screen? – Sam Nov 05 '14 at 10:21

Toast created in an IntentService never goes away

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