Develop Reference

Continually Running Background Service

I'm targeting sdk version 27 with a minimum version of 19 and trying to get a service that runs continuously in the background. I tried different service start options but it still got killed with the app. I tried using a BroadcastReceiver to start the service when it got killed but that gave me an error saying that the app was in the background and couldn't start a service so I tried using the JobScheduler and that gave me the same error. How is this supposed to be done? For example, if I were making a pedometer app, how could I keep that running in the background?

In oreo release Android defined limits to background services.
To improve the user experience, Android 8.0 (API level 26) imposes
limitations on what apps can do while running in the background.
Still if app need to run its service always, then we can create foreground service.
Background Service Limitations: While an app is idle, there are limits
to its use of background services. This does not apply to foreground
services, which are more noticeable to the user.
So create a foreground service. In which you will put a notification for user while your service is running. See this answer (There are many others)
Now what if you don't want a notification for your service. A solution is for that.
You can create some periodic task that will start your service, service will do its work and stops itself. By this your app will not be considered battery draining.
You can create periodic task with Alarm Manager, Job Scheduler, Evernote-Jobs or Work Manager.
Instead of telling pros & cons of each one. I just tell you best. Work manager is best solution for periodic tasks. Which was introduced with Android Architecture Component.
Unlike Job-Scheduler(only >21 API) it will work for all versions.
Also it starts work after a Doze-Standby mode.
Make a Android Boot Receiver for scheduling service after device boot.
I created forever running service with Work-Manager, that is working perfectly.

Since Android 8.0 many background service limitations have been introduced.
Two solutions:
if you need to get total control of task and execution timing, you have to choose Foreground Service.
Pros: your app will be considered to be alive, then is more unlikely that the os will kill it to free resources.
Cons: your user will always see the Foreground Notification.
if you need to schedule periodically task, then Work Manager (introduced in Google I/O 18) is the best solution. This component choose the best possible scheduler (Jobscheduler, JobDispatcher, AlarmManager..). Keep in mind that work manager APIs are useful only for the tasks that require guaranteed execution and they are deferrable.
Ref: Android Dev Documentation

The only solution I would suggest is using Firebase Cloud Messages.
Or foreground services.

Using BroadcastReciever we can run backgrouund service continuously, but if it will get killed , destroy automatically re-instance the old service instance
When service stops forcefully it will call onDestroy() method, in this case use one receiver and send one broadcast when ever service destroy and restart service again. in thee following method com.android.app is custom action of reciever class which extends BroadcastReciever
public void onDestroy() {
try {
myTimer.cancel();
timerTask.cancel();
} catch (Exception e) {
e.printStackTrace();
}
Intent intent = new Intent("com.android.app");
intent.putExtra("valueone", "tostoreagain");
sendBroadcast(intent);
}
and in onReceive Method
#Override
public void onReceive(Context context, Intent intent) {
Log.i("Service Stoped", "call service again");
context.startService(new Intent(context, ServiceCheckWork.class));
}
In case device is restarted then we have onBootCompleted action for receiver to catch
When you are targeting SdkVersion "O"
In MainActivity.java define getPendingIntent()
private PendingIntent getPendingIntent() {
Intent intent = new Intent(this, YourBroadcastReceiver.class);
intent.setAction(YourBroadcastReceiver.ACTION_PROCESS_UPDATES);
return PendingIntent.getBroadcast(this, 0, intent,
PendingIntent.FLAG_UPDATE_CURRENT);
}
here we use PendingIntent with BroadcastReceiver and This BroadcastReceiver has already been defined in AndroidManifest.xml.
Now in YourBroadcastReceiver.java class which contains an onReceive() method:
Override
public void onReceive(Context context, Intent intent) {
if (intent != null) {
final String action = intent.getAction();
if (ACTION_PROCESS_UPDATES.equals(action)) {
NotificationResult result = NotificationResult.extractResult(intent);
if (result != null) {
List<Notification> notifications = result.getNotification();
NotificationResultHelper notificationResultHelper = new
NotificationResultHelper(
context, notifications);
// Save the notification data to SharedPreferences.
notificationResultHelper.saveResults();
// Show notification with the notification data.
notificationResultHelper.showNotification();
Log.i(TAG,
NotificationResultHelper.getSavedNotificationResult(context));
}
}
}
}

as you say:
I tried using a BroadcastReceiver to start the service when it got
killed but that gave me an error saying that the app was in the
background and couldn't start a service
in Oreo when you are in background and you want to start a service that service must be a foreground service use this code:
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O) {
context.startForegroundService(intent);
} else {
context.startService(intent);
}
if you use this code in Oreo you have a few seconds in onStartCommand to start foreground otherwise your service considered as not responding and may be force close by user (in Android 8 or above)
There is no need to use BroadcastReceiver to start service after it is closed it is enough to just return START_STICKY or START_REDELIVER_INTENT from onStartCommand of your service to restart service after it is closed

A working hack for this is to simply start a foreground service which is only visible for the fraction of a second and starts your background service. In the background service you'd then periodically start the foreground service.
Before I give an example you should really ask yourself if this is the way to go for you, there might be other solutions to given problems (like using JobIntentService etc.); and keep in mind that this is a hack, it might be patched some time around and I'd generally not use it (I tested it with screen off and battery saving enabled though and it stayed alive the whole time - but this might prevent your device from dozing.. again, this is a dirty hack!)
Example:
public class TemporaryForegroundService extends Service {
public static final int NOTIFICATION_ID = 666;
private static Notification notification;
#Override
public void onCreate() {
super.onCreate();
if(notification == null)
notification = new NotificationCompat.Builder(this, NotificationChannels.importantChannel(this)).
setSmallIcon(R.mipmap.ic_launcher).setContentTitle("The unseen blade").setContentText("If you see me, congrats to you.").build();
startForeground(NOTIFICATION_ID, notification);
startService(new Intent(this, PermanentBackgroundService.class));
stopForeground(true);
stopSelf();
}
#Override
public int onStartCommand(Intent intent, int flags, int startId) {
return START_NOT_STICKY;
}
#Nullable
#Override
public IBinder onBind(Intent intent) {
return null;
}
}
public class PermanentBackgroundService extends Service {
private Runnable keepAliveRunnable = new Runnable() {
#Override
public void run() {
keepServiceAlive();
if(handler != null) handler.postDelayed(this, 15*1000);
}
};
private Handler handler;
public void onCreate(){
handler = new Handler();
handler.postDelayed(keepAliveRunnable, 30* 1000);
}
public void onDestroy() {
super.onDestroy();
keepServiceAlive();
}
private void keepServiceAlive() {
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O) {
startForegroundService(new Intent(PermanentBackgroundService.this, TemporaryForegroundService .class));
} else {
startService(new Intent(PermanentBackgroundService.this, TemporaryForegroundService .class));
}
}
}

BroadcastReceiver in IntentService in WakefulBroadcastReceiver does not always work

So, I have this problem.
I'm using a dependency project that is some kind of GCM notification parser. It's a bit poorly written, however I'm forced to use it, becase of work related reasons. Anyways:
The main service (that extends IntentService) is launched with WakefulBroadcastReceiver.
After it receives message from GCM I does some magic and sends it to the main App using broadcast.
In main app I'm constantly running service with another BroadcastReceiver that catches messages and saves everything in database etc.
Why is it so complicated? Firstly - originally it was someone else's project and now I'm trying to fix bugs. Secondly - I have no access from dependency to the main application project so I pass messages with broadcasts.
And now, the fun part. I need to filter whether I want to show notification or not. While sending a message to my main AppService I check it with the history of previous messages and then I decide if I need to show this message to User or not. However, no matter what my decision is, my dependency still shows my notification.
So I added yet another broadcast, when after successful validation I launch in my dependency notification building method.
Here is the code:
My WakefulBroadcastReceiver:
public class GcmBroadcastReceiver extends WakefulBroadcastReceiver {
#Override
public void onReceive(Context context, Intent intent) {
ComponentName comp = new ComponentName(context.getPackageName(), PushService.class.getName());
startWakefulService(context, (intent.setComponent(comp)));
setResultCode(Activity.RESULT_OK);
}
}
Here is my Depencency service
public NotificationCheckerReceiver notificationCheckerReceiver;
...
#Override
protected void onHandleIntent(Intent intent) {
Bundle extras = intent.getExtras();
GoogleCloudMessaging gcm = GoogleCloudMessaging.getInstance(this);
String messageType = gcm.getMessageType(intent);
if (!extras.isEmpty()) {
if (GoogleCloudMessaging.MESSAGE_TYPE_MESSAGE.equals(messageType)) {
//Launch my "approval" receiving broadcast
launchBroadcastReceiver(extras, intent);
//send broadcast to main app with the message we will parse etc.
sendSmsBroadcast(...));
}
}
}
#Override
public void onDestroy() {
unregisterReceiver(notificationCheckerReceiver);
super.onDestroy();
}
//Launch to build notification
public void showNotification(Bundle extras){
...
//Basic notification builder
}
//Receive broadcast from DB if notification was already in the DB
private void launchBroadcastReceiver(Bundle extras, Intent intent){
Log.d(TAG, "Broadcast receiver loaded");
notificationCheckerReceiver = new NotificationCheckerReceiver(new NotiFlag() {
#Override
public void onReceiveApproval(Boolean flag, Intent intent, Bundle extras) {
Log.d(TAG, "Approved notification show");
showNotification(extras);
JustPushGcmBroadcastReceiver.completeWakefulIntent(intent);
}
}, intent, extras);
registerReceiver(notificationCheckerReceiver, new IntentFilter(notificationCheckerReceiver.INTENT_EVENT_NAME));
}
public void sendSmsBroadcast(String message, boolean isAppOnScreen){
...
//This works
}
}
and my "faulty" receiver:
public class NotificationCheckerReceiver extends BroadcastReceiver{
private final String TAG = getClass().getSimpleName();
public static final String INTENT_EVENT_NAME = "NOTIFLAG";
public static final String INTENT_FLAG_KEY = "FLAG";
Intent intent;
Bundle extras;
NotiFlag nofiFlag;
public NotificationCheckerReceiver(NotiFlag nofiFlag, Intent intent, Bundle extras){
Log.d(TAG, "Launched constructor NotificationChecker");
this.nofiFlag = nofiFlag;
this.intent = intent;
this.extras = extras;
}
#Override
public void onReceive(Context context, Intent intent) {
Log.d(TAG, "Launched onReceive");
Boolean bool = intent.getExtras().getBoolean(INTENT_FLAG_KEY);
Log.d(TAG, "___________Broadcast receiver got something and it is intent: "+bool);
if (bool != false) {
nofiFlag.onReceiveApproval(bool, this.intent, this.extras);
}
}
}
and lastly, what I'm sending from my main service:
public void sendNotificationCheckerBroadcast(Boolean message){
Intent flag = new Intent(NotificationCheckerReceiver.INTENT_EVENT_NAME);
flag.putExtra(NotificationCheckerReceiver.INTENT_FLAG_KEY, message);
DvLogs.d(TAG, "__________Sending intent: "+message);
sendBroadcast(flag);
}
What happens is that eveything to the point where I launch "sendNotificationCheckerBroadcast()". I get that I'm sending some kind of boolean... and that's it.
The funny part is: it SOMETIMES works.
I don't know why, but when for some reason it launches - everything is awesome.
EDIT:
When it works, because sometimes it does, I have this error:
01-15 11:20:22.204 3234-3234/pl.digitalvirgo.lafarge E/ActivityThread﹕ Service com.example.name.PushService has leaked IntentReceiver com.example.name.NotificationCheckerReceiver#43042b50 that was originally registered here. Are you missing a call to unregisterReceiver()?
android.app.IntentReceiverLeaked: Service com.example.name.PushService has leaked IntentReceiver com.example.name.NotificationCheckerReceiver#43042b50 that was originally registered here. Are you missing a call to unregisterReceiver()?
at android.app.LoadedApk$ReceiverDispatcher.<init>(LoadedApk.java:814)
at android.app.LoadedApk.getReceiverDispatcher(LoadedApk.java:610)
at android.app.ContextImpl.registerReceiverInternal(ContextImpl.java:1772)
at android.app.ContextImpl.registerReceiver(ContextImpl.java:1752)
at android.app.ContextImpl.registerReceiver(ContextImpl.java:1746)
at android.content.ContextWrapper.registerReceiver(ContextWrapper.java:479)
at com.example.name.PushService.launchBroadcastReceiver(Unknown Source)
at com.example.name.PushService.onHandleIntent(Unknown Source)
at android.app.IntentService$ServiceHandler.handleMessage(IntentService.java:65)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:157)
at android.os.HandlerThread.run(HandlerThread.java:61)
Maybe it's somehow related?
I know that I should unRegister this Receiver ... somewhere. Tried onStop, but as we can see - no success.
Edit2:
Weird.
I believe, that the problem is in onStop() method. Probably it's called too early (?) so my Receiver has no chance to work. When I launch app without unRegister everything works. Of course I get bug above, but still... it's something.
Any ideas guys?

Well. The problem was inside the idea of IntentService.
intentService kills itself after onHandleIntent() method.
So the solution for this problem is to change IntentService into Service remembering to handle stopping this thing.

GCM Android Push Notification: send OK but not delivered

I'm trying to send push notification to android devices. I have not problem to register the ID of the emulator or the devices, but it's impossibile to receive messages also if the send status is 200 OK.
I also try to look to firewall settings, but it's already turned off.
I tried also to use PushBots service from web: same thing. Device registered correctly, message sent, but not delivered to emulator or devices.

It was my mistake. I didn't notice the app was giving me exception when sending push from web for an error in the manifest Receiver.
Implemented the NotificationManager now I receive the push messagge into device.
public class GcmBroadcastReceiver extends WakefulBroadcastReceiver {
#Override
public void onReceive(Context context, Intent intent) {
// Explicitly specify that GcmMessageHandler will handle the intent.
ComponentName comp = new ComponentName(context.getPackageName(),
GcmMessageHandler.class.getName());
// Start the service, keeping the device awake while it is launching.
startWakefulService(context, (intent.setComponent(comp)));
setResultCode(Activity.RESULT_OK);
}
}
#Override
protected void onHandleIntent(Intent intent) {
Bundle extras = intent.getExtras();
GoogleCloudMessaging gcm = GoogleCloudMessaging.getInstance(this);
String messageType = gcm.getMessageType(intent);
mes = extras.getString("title");
sendNotification(mes);
sendAlert(mes);
Log.i("GCM", "Received : (" +messageType+") "+extras.getString("title"));
GcmBroadcastReceiver.completeWakefulIntent(intent);
}

Stop IntentService from inside my application?

I'm building some kind of chat program that uses GCM to notify the user that a message is available. I followed the gcm client example using a WakefulBroadcastReceiver and IntentService and everything works as expected.
The BroadcastReceiver:
public class GcmBroadcastReceiver extends WakefulBroadcastReceiver {
#Override
public void onReceive(Context context, Intent intent) {
// Explicitly specify that GcmIntentService will handle the intent.
ComponentName comp = new ComponentName(context.getPackageName(), GcmIntentService.class.getName());
// Start the service, keeping the device awake while it is launching.
startWakefulService(context, (intent.setComponent(comp)));
setResultCode(Activity.RESULT_OK);
}
}
and the IntentService:
public class GcmIntentService extends IntentService {
public static final int NOTIFICATION_ID = 1;
private NotificationManager mNotificationManager;
public GcmIntentService() {
super("GcmIntentService");
}
public static final String TAG = "IOAN";
#Override
protected void onHandleIntent(Intent intent) {
Bundle extras = intent.getExtras();
GoogleCloudMessaging gcm = GoogleCloudMessaging.getInstance(this);
// The getMessageType() intent parameter must be the intent you received
// in your BroadcastReceiver.
String messageType = gcm.getMessageType(intent);
if (!extras.isEmpty()) { // has effect of unparcelling Bundle
if (GoogleCloudMessaging.MESSAGE_TYPE_MESSAGE.equals(messageType)) {
// Post notification of received message.
sendNotification(extras.getString("sender"), extras.getString("message"));
Log.i(TAG, "Received: " + extras.toString());
}
}
// Release the wake lock provided by the WakefulBroadcastReceiver.
GcmBroadcastReceiver.completeWakefulIntent(intent);
}
//... more stuff
}
So the IntentService sends a notification to my application.
Now, when the user closes my application (back button -> are you sure you want to exit? -> yes), I want to also have a check box "do you still want to receive messages?" (or something like that), and if the user chooses not to receive messages, I want to stop the service that handles the gcm message and restart it when the app runs again.
How do I do that?
Edit: I tried stopService(new Intent(MainActivity.this,GcmIntentService.class)); but I still get the notifications.
Edit 2: Seems like a boolean value in SharedPreferences works fine... any better solution?

Propagate Result to next BroadcastReceiver in android

I have 2 receivers and 2 GCMIntentService classes for GCM in my application; one inside my app and another one is included in a library that i have added to my application.When a message is received through GCM; I would want to some how identify which intentservice a received message is intented for and let the correct reciever handle it. Some one suggested here to propagate result to the next receiver if its not intended for mine but i couldnt manage to do it. I would really appreciate if some one could help me with that.

Ok I have managed to solve it. Thanks to #Eran for his help. I was using the deprecated GCM api. The default implementation of GCMBroadcastReceiver had
setResult(Activity.RESULT_OK, null /* data */, null /* extra */);
in onReceive() method. This would prevent passing the result on to the next receiver. I tried to overide the onReceive method but it was final and wouldn't allow me overide it. So, i switched to the new GoogleCloudMessaging api and defined a custom Broadcast receiver and in its onReceive() metod i did this :
#Override
public void onReceive(Context context, Intent intent) {
String message = intent.getExtras().getString("identifier_tag");
// ignore if message not intended for us
if (message == null) {
setResultCode(Activity.RESULT_OK);
return;
}
if (!message.equals(IDENTIFIER_TAG)) {
setResultCode(Activity.RESULT_OK);
return;
}
ComponentName comp = new ComponentName(context.getPackageName(),
GcmIntentService.class.getName());
// Start the service, keeping the device awake while it is
// launching.
startWakefulService(context, (intent.setComponent(comp)));
// message has been handled; do not propagate
setResult(Activity.RESULT_OK, null, null);
}
What i did was to check if the received message was intended for me. If yes, i would invoke the intent service and setResult(Activity.RESULT_OK, null, null); would stop the message from being passed on to other receivers. If message wasn't intended for me, i would pass it to the next receiver. also in the manifest file, i set the priority for this receiver higher to make sure it receive the message first.