Toast Created in an Intentservice Never Goes Away

How to create toast from IntentService? It gets stuck on the screen

in onCreate() initialize a Handler and then post to it from your thread.

private class DisplayToast implements Runnable{
  String mText;

  public DisplayToast(String text){
    mText = text;
  }

  public void run(){
     Toast.makeText(mContext, mText, Toast.LENGTH_SHORT).show();
  }
}
protected void onHandleIntent(Intent intent){
    ...
  mHandler.post(new DisplayToast("did something")); 
}

Android Service to show toast

See this part of the docs

(An IntentService has a few limitations:

It can't interact directly with your user interface. To put its
results in the UI, you have to send them to an Activity.

You need to put it on the main Thread. See the answer here by rony of a way to do that.

and from the full documentation on IntentService

handles each Intent in turn using a worker thread

How to display Toast from a Service after main Activity finishes?

OnHandleIntent will run in a differant Thread
so you are showing Toast in a thread which is not allowed in android

so change your code like this

Handler handler = new Handler(Looper.getMainLooper());
handler.post(new Runnable() {

    @Override
    public void run() {
         Toast.makeText(getApplicationContext(), 
                       getString(R.string.car_opened), 
                       Toast.LENGTH_SHORT).show();              
    }
});

From this dead thread in service

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.

Android Toast Won't Disappear

The only explanation is that your Toast is called in a loop. You should track the toast .show() and see if it is not called an infinite times.

An other visual way would be to do this

 Toast.makeText(SugarLoafContext.playbackTabContext, "No clips found.", duration).show();
 Toast.makeText(SugarLoafContext.playbackTabContext, "Do you understand now?", duration).show();

I am sure you will see both toast alternatively during a looong time...

Dialog: MyActivity has stopped

Your service might be in a different thread.
Use handler to show Toast:

Handler handler = new Handler();
Runnable toastRunnable = new Runnable(){ 
@Override public void run() { 
Toast.makeText(MyService.this, "onCreate: Service work!", Toast.LENGTH_SHORT).show(); 
    } 
};

handler.post(toastRunnable);

How to show a toast from a worker thread inside a service?

First of all, you really shouldn't send Toast messages from a Service or from any task that wasn't initiated by the user a very short time ago. Otherwise the user won't know where the Toast is originating from; she can't even be sure from which app it comes - absolutely confusing and bad practice in general.

But to answer your question, when you create a Handler with new Handler() then it is attached to the thread it was created on. Thus, if you want to post something to the UI/main thread from a service (from any thread) then you should create the Handler in, for instance, the onCreate() method; because onCreate(), and usually any Android callback method, is called on the UI thread. So:

public class MyService extends Service {

    private Handler mMainThreadHandler;

    @Override
    public void onCreate() {
        mMainThreadHandler = new Handler();
    }

    [...]
}

Or, of you want to create a Handler that is attached to the UI thread and don't want to care about where it is created then use new Handler(Looper.getMainLooper()). This way it is attached to the main looper; which is the looper of the main thread.

public class MyService extends Service {

    private Handler mMainThreadHandler = new Handler(Looper.getMainLooper());

    [...]
}

I know you wrote you tried it; but it should work.

Though, what I would recommend you is not to bother with Handlers; use Needle instead. Needle is a simple and powerful multithreading library for Android. With it, you can say things like:

Needle.onMainThread().execute(new Runnable() {
    @Override
    public void run() {
        // e.g. change one of the views
    }
});

Check it out on GitHub: https://github.com/ZsoltSafrany/needle

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