Android Service for playing music: why START_STICKY?

user_2828064 0
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I am working on an android app to play music.

So far I have returned START_STICKY from the onStartCommand of the Service responsible for playing the music without much thought becuase the tooltip in Eclipse states: "This mode makes sense for [...] a service performing background music playback".

The first thing this method does is looking in the intent what it is supposed to do (play, stop, next song, ...).

Recently when I killed the app while playing music (by dragging it out of the screen in the overview of recent apps) the app crashed. Looking in the log file I found that a NullPointerException was thrown when trying to access the intent in onStartCommand (after the Apllications's and Service's onCreate methods had been called).

My first reflex was to therefore insert at the beginning of the onStartCommand method:

if (intent == null){
    stopSelf();
    return START_NOT_STICKY;
}

But after reading the descriptions of START_STICKY and START_NOT_STICKY again I am wondering: Why would START_STICKY be recommended for a music player?

The way I understand it is that the difference between the two is that if a service started with START_STICKY is killed it will be restarted (then with intent=null). With START_NOT_STICKY the service will not be restarted (unless the user requests it), therefore it will always be called with an intent and I would not need to check whether it is null or not.

When the user kills the app it seems obvious to me that the service should not be restarted.

The other case I can think of where the service might be restarted is if the service had been killed by the system due to a lack of ressources. In that case, too, I don't think a user would want the music to unexpectedly start playing music just becuase some ressources became available.

The following two answers imply that the return code has no other meaning than whether the service should be restarted if the process was killed:

Why is START_STICKY recommended for a music player?

android-service android
2 Answers

START_STICKY- If the service is stopped due to low memory then service is recreated when sufficient memory is available, after it recovers from low memory. Here you will lose the results that might have computed before.

START_NOT_STICKY- If the service is stopped the system not to bother to restart the service, even when it has sufficient memory.

Also when user kills the app the service wont be stopped unless you stop the process by using some task killers.For more info on service check this link.

http://www.vogella.com/tutorials/AndroidServices/article.html

user_66026750

int START_STICKY: Constant to return from onStartCommand(Intent, int, int): if this service's process is killed while it is started (after returning from onStartCommand(Intent, int, int)), then leave it in the started state but don't retain this delivered intent. Later the system will try to re-create the service. Because it is in the started state, it will guarantee to call onStartCommand(Intent, int, int) after creating the new service instance; if there are not any pending start commands to be delivered to the service, it will be called with a null intent object, so you must take care to check for this.This mode makes sense for things that will be explicitly started and stopped to run for arbitrary periods of time, such as a service performing background music playback.

so it is self-exolanatory refer this STICKY SERVICE

user_55106660
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