Android keep Service running when app is killed

Question

I want to keep a IntentService running in background even when the app is killed  And by  killed  I mean press home-button for a long time -  see all running apps -  swipe my app aside -  app killed OR press back-button for a long time -  app killed  My code goes as follows  In my MainActivity   Intent intent   new Intent this  MyService class   this startService intent     In my MyService   public class MyService extends IntentService     Override protected void onHandleIntent Intent intent        System out println  MyService started        run       private void run         while  true           System out println  MyService still running            doSomething            waitSomeTime                 I see that the service is running when the app is open  It s still running when I minimize the app via home-button  It s still running when I close the app via back-button  But it will stop if I kill it as mentioned above  How do I solve this

User · Answer

inside onstart command put START STICKY    This service won t kill unless it is doing too much task and kernel wants to kill it for it      Override         public int onStartCommand Intent intent  int flags  int startId                Log i  LocalService    Received start id     startId          intent                  We want this service to continue running until it is explicitly                stopped  so return sticky              return START STICKY

User · Answer

If your Service is started by your app then actually your service is running on main process  so when app is killed service will also be stopped  So what you can do is  send broadcast from onTaskRemoved method of your service as follows    Intent intent   new Intent  com android ServiceStopped     sendBroadcast intent     and have an broadcast receiver which will again start a service  I have tried it  service restarts from all type of kills

User · Answer

You can use android stopWithTask  false in manifest as bellow  This means even if user kills app by removing it from tasklist  your service won t stop     lt service android name   service StickyService                    android stopWithTask  false   gt

User · Answer

In your service  add the following code    Override public void onTaskRemoved Intent rootIntent       Intent restartServiceIntent   new Intent getApplicationContext    this getClass         restartServiceIntent setPackage getPackageName          PendingIntent restartServicePendingIntent   PendingIntent getService getApplicationContext    1  restartServiceIntent  PendingIntent FLAG ONE SHOT       AlarmManager alarmService    AlarmManager  getApplicationContext   getSystemService Context ALARM SERVICE       alarmService set      AlarmManager ELAPSED REALTIME      SystemClock elapsedRealtime     1000      restartServicePendingIntent        super onTaskRemoved rootIntent

User · Answer

All the answers seem correct so I ll go ahead and give a complete answer here  Firstly  the easiest way to do what you are trying to do is launch a Broadcast in Android when the app is killed manually  and define a custom BroadcastReceiver to trigger a service restart following that  Now lets jump into code   Create your Service in YourService java Note the onCreate   method  where we are starting a foreground service differently for Build versions greater than Android Oreo  This because of the strict notification policies introduced recently where we have to define our own notification channel to display them correctly  The this sendBroadcast broadcastIntent   in the onDestroy   method is the statement which asynchronously sends a broadcast with the action name  quot restartservice quot   We ll be using this later as a trigger to restart our service  Here we have defined a simple Timer task  which prints a counter value every 1 second in the Log while incrementing itself every time it prints  public class YourService extends Service   public int counter 0        Override     public void onCreate             super onCreate            if  Build VERSION SDK INT  gt  Build VERSION CODES O              startMyOwnForeground            else             startForeground 1  new Notification                 RequiresApi Build VERSION CODES O      private void startMyOwnForeground                 String NOTIFICATION CHANNEL ID    quot example permanence quot           String channelName    quot Background Service quot           NotificationChannel chan   new NotificationChannel NOTIFICATION CHANNEL ID  channelName  NotificationManager IMPORTANCE NONE           chan setLightColor Color BLUE           chan setLockscreenVisibility Notification VISIBILITY PRIVATE                    NotificationManager manager    NotificationManager  getSystemService Context NOTIFICATION SERVICE           assert manager    null          manager createNotificationChannel chan            NotificationCompat Builder notificationBuilder   new NotificationCompat Builder this  NOTIFICATION CHANNEL ID           Notification notification   notificationBuilder setOngoing true                   setContentTitle  quot App is running in background quot                    setPriority NotificationManager IMPORTANCE MIN                   setCategory Notification CATEGORY SERVICE                   build            startForeground 2  notification                Override     public int onStartCommand Intent intent  int flags  int startId            super onStartCommand intent  flags  startId           startTimer            return START STICKY               Override     public void onDestroy             super onDestroy            stoptimertask             Intent broadcastIntent   new Intent            broadcastIntent setAction  quot restartservice quot            broadcastIntent setClass this  Restarter class           this sendBroadcast broadcastIntent                private Timer timer      private TimerTask timerTask      public void startTimer             timer   new Timer            timerTask   new TimerTask                 public void run                     Log i  quot Count quot    quot             quot    counter                                       timer schedule timerTask  1000  1000                 public void stoptimertask             if  timer    null                timer cancel                timer   null                        Nullable      Override     public IBinder onBind Intent intent            return null            Create a Broadcast Receiver to respond to your custom defined broadcasts in Restarter java The broadcast with the action name  quot restartservice quot  which you just defined in YourService java is now supposed to trigger a method which will restart your service  This is done using BroadcastReceiver in Android  We override the built-in onRecieve   method in BroadcastReceiver to add the statement which will restart the service  The startService   will not work as intended in and above Android Oreo 8 1  as strict background policies will soon terminate the service after restart once the app is killed  Therefore we use the startForegroundService   for higher versions and show a continuous notification to keep the service running  public class Restarter extends BroadcastReceiver        Override     public void onReceive Context context  Intent intent            Log i  quot Broadcast Listened quot    quot Service tried to stop quot            Toast makeText context   quot Service restarted quot   Toast LENGTH SHORT  show             if  Build VERSION SDK INT  gt   Build VERSION CODES O                context startForegroundService new Intent context  YourService class              else               context startService new Intent context  YourService class                        Define your MainActivity java to call the service on app start  Here we define a separate isMyServiceRunning   method to check the current status of the background service  If the service is not running  we start it by using startService    Since the app is already running in foreground  we need not launch the service as a foreground service to prevent itself from being terminated  Note that in onDestroy   we are dedicatedly calling stopService    so that our overridden method gets invoked  If this was not done  then the service would have ended automatically after app is killed without invoking our modified onDestroy   method in YourService java public class MainActivity extends AppCompatActivity       Intent mServiceIntent      private YourService mYourService        Override     protected void onCreate Bundle savedInstanceState            super onCreate savedInstanceState           setContentView R layout activity main            mYourService   new YourService            mServiceIntent   new Intent this  mYourService getClass             if   isMyServiceRunning mYourService getClass                   startService mServiceIntent                        private boolean isMyServiceRunning Class lt   gt  serviceClass            ActivityManager manager    ActivityManager  getSystemService Context ACTIVITY SERVICE           for  ActivityManager RunningServiceInfo service   manager getRunningServices Integer MAX VALUE                 if  serviceClass getName   equals service service getClassName                       Log i   quot Service status quot    quot Running quot                    return true                                  Log i   quot Service status quot    quot Not running quot            return false               Override     protected void onDestroy               stopService mServiceIntent           Intent broadcastIntent   new Intent            broadcastIntent setAction  quot restartservice quot            broadcastIntent setClass this  Restarter class           this sendBroadcast broadcastIntent           super onDestroy              Finally register them in your AndroidManifest xml All of the above three classes need to be separately registered in AndroidManifest xml  Note that we define an intent-filter with the action name as  quot restartservice quot  where the Restarter java is registered as a receiver  This ensures that our custom BroadcastReciever is called whenever the system encounters a broadcast with the given action name   lt application     android allowBackup  quot true quot      android icon  quot  mipmap ic launcher quot      android label  quot  string app name quot      android supportsRtl  quot true quot      android theme  quot  style AppTheme quot  gt        lt receiver         android name  quot Restarter quot          android enabled  quot true quot          android exported  quot true quot  gt           lt intent-filter gt               lt action android name  quot restartservice quot    gt           lt  intent-filter gt       lt  receiver gt        lt activity android name  quot MainActivity quot  gt           lt intent-filter gt               lt action android name  quot android intent action MAIN quot    gt               lt category android name  quot android intent category LAUNCHER quot    gt           lt  intent-filter gt       lt  activity gt        lt service         android name  quot YourService quot          android enabled  quot true quot   gt       lt  service gt   lt  application gt   This should now restart your service again if the app was killed from the task-manager  This service will keep on running in background as long as the user doesn t Force Stop the app from Application Settings  UPDATE  Kudos to Dr jacky for pointing it out  The above mentioned way will only work if the onDestroy   of the service is called  which might not be the case certain times  which I was unaware of  Thanks

User · Answer

The reason for this is that you are trying to use an IntentService  Here is the line from the API Docs      The IntentService does the following       Stops the service after all start requests have been handled  so you   never have to call stopSelf      Thus if you want your service to run indefinitely i suggest you extend the Service class instead  However this does not guarantee your service will run indefinitely  Your service will still have a chance of being killed by the kernel in a state of low memory if it is low priority So you have two options  1 Keep it running in the foreground by calling the startForeground    method  2 Restart the service if it gets killed    Here is a part of the example from the docs where they talk about restarting the service after it is killed    public int onStartCommand Intent intent  int flags  int startId          Toast makeText this   service starting   Toast LENGTH SHORT  show              For each start request  send a message to start a job and deliver the           start ID so we know which request we re stopping when we finish the job        Message msg   mServiceHandler obtainMessage          msg arg1   startId        mServiceHandler sendMessage msg             If we get killed  after returning from here  restart        return START STICKY

[android] Android: keep Service running when app is killed

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