Android – Service vs IntentService in the Android platform

androidandroid-intentserviceandroid-servicemultithreading

I am seeking an example of something that can be done with an IntentService that cannot be done with a Service (and vice-versa)?

I also believe that an IntentService runs in a different thread and a Service does not. So, as far as I can see, starting a service within its own thread is like starting an IntentService. Is that correct?

Best Answer

Tejas Lagvankar wrote a nice post about this subject. Below are some key differences between Service and IntentService.

When to use?

The Service can be used in tasks with no UI, but shouldn't be too long. If you need to perform long tasks, you must use threads within Service.
The IntentService can be used in long tasks usually with no communication to Main Thread. If communication is required, can use Main Thread handler or broadcast intents. Another case of use is when callbacks are needed (Intent triggered tasks).

How to trigger?

The Service is triggered by calling method startService().
The IntentService is triggered using an Intent, it spawns a new worker thread and the method onHandleIntent() is called on this thread.

Triggered From

The Service and IntentService may be triggered from any thread, activity or other application component.

Runs On

The Service runs in background but it runs on the Main Thread of the application.
The IntentService runs on a separate worker thread.

Limitations / Drawbacks

The Service may block the Main Thread of the application.
The IntentService cannot run tasks in parallel. Hence all the consecutive intents will go into the message queue for the worker thread and will execute sequentially.

When to stop?

If you implement a Service, it is your responsibility to stop the service when its work is done, by calling stopSelf() or stopService(). (If you only want to provide binding, you don't need to implement this method).
The IntentService stops the service after all start requests have been handled, so you never have to call stopSelf().

Related Solutions

Android – How to check if a service is running on Android

I use the following from inside an activity:

private boolean isMyServiceRunning(Class<?> serviceClass) {
    ActivityManager manager = (ActivityManager) getSystemService(Context.ACTIVITY_SERVICE);
    for (RunningServiceInfo service : manager.getRunningServices(Integer.MAX_VALUE)) {
        if (serviceClass.getName().equals(service.service.getClassName())) {
            return true;
        }
    }
    return false;
}

And I call it using:

isMyServiceRunning(MyService.class)

This works reliably, because it is based on the information about running services provided by the Android operating system through ActivityManager#getRunningServices.

All the approaches using onDestroy or onSometing events or Binders or static variables will not work reliably because as a developer you never know, when Android decides to kill your process or which of the mentioned callbacks are called or not. Please note the "killable" column in the lifecycle events table in the Android documentation.

Android – How to close/hide the Android soft keyboard programmatically

You can force Android to hide the virtual keyboard using the InputMethodManager, calling hideSoftInputFromWindow, passing in the token of the window containing your focused view.

// Check if no view has focus:
View view = this.getCurrentFocus();
if (view != null) {  
    InputMethodManager imm = (InputMethodManager)getSystemService(Context.INPUT_METHOD_SERVICE);
    imm.hideSoftInputFromWindow(view.getWindowToken(), 0);
}

This will force the keyboard to be hidden in all situations. In some cases, you will want to pass in InputMethodManager.HIDE_IMPLICIT_ONLY as the second parameter to ensure you only hide the keyboard when the user didn't explicitly force it to appear (by holding down the menu).

Note: If you want to do this in Kotlin, use: context?.getSystemService(Context.INPUT_METHOD_SERVICE) as InputMethodManager

Kotlin Syntax

// Only runs if there is a view that is currently focused
this.currentFocus?.let { view ->
    val imm = getSystemService(Context.INPUT_METHOD_SERVICE) as? InputMethodManager
    imm?.hideSoftInputFromWindow(view.windowToken, 0)
}

Best Answer

Related Solutions

Android – How to check if a service is running on Android

Android – How to close/hide the Android soft keyboard programmatically

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