Develop Reference

How to run a Service in an android wear forever

I am trying to create a service(in smart watch) which should run forever even if the user is not using the app. Main purpose is to use the service for Speech Recognition. So whenever user say a specific word the app should be able to respond just like google voice.
However, for test purpose, I am printing an integer in the Log, but it only executed once. that means the service is not running forever.
My service code:
public class VoiceService extends Service {
private IBinder mBinder = new VoiceBinder();
int i = 1;
public VoiceService() {
}
#Override
public void onCreate() {
super.onCreate();
updateLog();
}
public void updateLog() {
++i;
Log.v("DATA", Integer.toString(i));
}
#Override
public IBinder onBind(Intent intent) {
// TODO: Return the communication channel to the service.
return mBinder;
}
//inner helper class
public class VoiceBinder extends Binder {
//constructor
VoiceService getService() {
return VoiceService.this;
}
}
}
My MainActivity Code:
serviceConnection = new ServiceConnection() {
#Override
public void onServiceConnected(ComponentName componentName, IBinder iBinder) {
VoiceService.VoiceBinder binder = (VoiceService.VoiceBinder) iBinder;
iBinder = (IBinder) binder.getService();
MainActivity.this.voiceService = ((VoiceService.VoiceBinder)iBinder).getService();
}
#Override
public void onServiceDisconnected(ComponentName componentName) {
voiceService = null;
}
};
//bind service
bindService(new Intent(this, VoiceService.class), serviceConnection, getApplicationContext().BIND_AUTO_CREATE);
startService(new Intent(this, VoiceService.class));
AndroidManifest:
<service
android:name=".VoiceService"
android:enabled="true"
android:exported="false">
</service>
My output:
12-20 22:27:20.307 23624-23624/? V/DATA: 2

You might want to go through Running in a Background Service wherein it mentions that
Long-running foreground operations can cause problems and interfere with the responsiveness of your user interface, which annoys your users and can even cause system errors. To avoid this, the Android framework offers several classes that help you off-load operations onto a separate thread that runs in the background. The most useful of these is IntentService.
And, also note that:
If your app targets Android 5.0 (API level 21), you should use JobScheduler to execute background services.
For best application's performance and minimize draining of battery, you may want to also check the following links:
Best Practices for Background Jobs
Adding Voice Capabilities
Create a background service in android wear

Which function is called when application is removed from task manager

I need to make status of user offline. When I press home button onStop() is called, that's fine. When I press back button onDestroy() is invoked. But when I close the app from recent apps by swiping it, onStop() or onDestroy() isn't called.
I need to know when the app is closed from recent apps to do something (e.g make user offline).

Make a service :
public class MyService extends Service {
private DefaultBinder mBinder;
private AlarmManager alarmManager ;
private PendingIntent alarmIntent;
private void setAlarmIntent(PendingIntent alarmIntent){
this.alarmIntent=alarmIntent;
}
public void onCreate() {
alarmManager (AlarmManager)getSystemService(Context.ALARM_SERVICE);
mBinder = new DefaultBinder(this);
}
#Override
public IBinder onBind(Intent intent) {
return mBinder;
}
public void onTaskRemoved (Intent rootIntent){
alarmManager.cancel(alarmIntent);
this.stopSelf();
}
}
Make a custom class :
public class DefaultBinder extends Binder {
MyService s;
public DefaultBinder( MyService s) {
this.s = s;
}
public MyService getService() {
return s;
}
}
Add to your activity :
MyService service;
protected ServiceConnection mConnection = new ServiceConnection() {
public void onServiceConnected(ComponentName className, IBinder binder) {
service = ((DefaultBinder) binder).getService();
service.setAlarmIntent(pIntent);
}
public void onServiceDisconnected(ComponentName className) {
service = null;
}
};
protected void onResume() {
super.onResume();
bindService(new Intent(this, MainService.class), mConnection,
Context.BIND_AUTO_CREATE);
}
#Override
protected void onStop() {
super.onStop();
if (mConnection != null) {
try {
unbindService(mConnection);
} catch (Exception e) {}
}
}

But when I close the app from recent apps by swiping it, onStop() or onDestroy() isn't called.
Methods of Activity lifecycle that are to be called when Activity is no longer visible are not guaranteed to be called when removed from the recent tasks (treat it as "soft" version of killing an app by the system due to low memory).
I need to know when the app is closed from recent apps to do something (e.g make user offline)
I suggest one of the following:
(If applicable) use Activity's onResume()/onPause() to "make user online/offline";
use Service that sticks to the application meaning that if the app is killed after Service's onStartCommand() returns, the service will be recreated and onStartCommand() will be called again. At this point you could "make user offline". The chain of lifecycle method calls would be:
Activity's onStop() -> onDestroy()* ->
Service's onTaskRemoved()* ->
Application's onCreate() -> Service's onCreate() ->
Service's onStartCommand()
The Intent passed to the method will help you recognize which component triggered the start request:
Intent != null, meaning the request has been received from a running Activity instance
Intent = null, meaning the request has been sent by the (newly created) Application instance
* Not guaranteed to be called

No, there is no clean way to get the application termination time. But I could suggest you a dirty trick to use a service to update your application (offline functionalities) for every after n minutes.
When OS kill your application, it will remove all associated services and broadcast receiver along with it.

How to implement a service that runs only when the app is running?

The app has a service which has to detect how many minutes the app is running and based on that, the service will initiate misc actions.
What is the proper way to implement this?
How can I be sure the service is running ONLY when the app is running in front of the user?
Starting the service seems easy - just start it on splash loading. But the harder part is ending it. I cannot just end it when the user press Back button on the last screen. How to handle situation when a user presses Home screen or some other other app (like phone call, or viber popup, or...) takes over the screen?
I tried taking suggestions from the other theme (How to start a android service from one activity and stop service in another activity?), but this does not handle the situation with Home button or other app taking over the screen.
The app has in total around 10 activities. Is it a proper way to bind this service to all 10 activities and when all are off, the service then turn itself off?

Make a BaseActivity for all of your Activities. In the BaseActivity, do the following:
public class MyActivity extends Activity implements ServiceConnection {
//you may add #override, it's optional
protected void onStart() {
super.onStart();
Intent intent = new Intent(this, MyService.class);
bindService(intent, this, 0);
}
//you may add #override, it's optional
protected void onStop() {
super.onStop();
unbindService(this);
}
public void onServiceConnected(ComponentName name, IBinder binder) {};
public void onServiceDisconnected(ComponentName name) {};
/* lots of other stuff ... */
}
Your BaseActivity will need to implement ServiceConnection interface (or you can use an anonymous inner class), but you can leave those methods empty.
In your Service class, you need to implement the onBind(Intent) method and return an IBinder. The easiest way to do that is like so:
public class MyService extends Service {
private final IBinder localBinder = new LocalBinder();
public void onCreate() {
super.onCreate();
// first time the service is bound, it will be created
// you can start up your timed-operations here
}
public IBinder onBind(Intent intent) {
return localBinder;
}
public void onUnbind(Intent intent) {
// called when the last Activity is unbound from this service
// stop your timed operations here
}
public class LocalBinder extends Binder {
MyService getService() {
return MyService.this;
}
}
}

Bound Service is define specifically for this purpose, you can bind Activities to it, and when all the Activities are gone, it will be stopped as well. The link should contain enough detail for you to implement.

OnBind() on service always returns False - Android

I'm trying to bind a service, but onBind() always returns false.
This is the code for the ServiceConnection-
private ServiceConnection mConnection = new ServiceConnection() {
public void onServiceConnected(ComponentName className, IBinder service) {
// This is called when the connection with our service has been established,
// giving us the service object we can use to interact with our service.
mBoundService = ((ScheduleService.ServiceBinder) service).getService();
}
public void onServiceDisconnected(ComponentName className) {
mBoundService = null;
}
};
This is call to bindService() -
boolean test = getApplicationContext().bindService(new Intent(this, ScheduleService.class), mConnection, Context.BIND_AUTO_CREATE);
This is the declaration of the service in the Manifest -
<service android:name=".Notifications.ScheduleService" android:enabled="true"/>
I've read previous questions regarding the subject and couldn't find an answer(tried switching the Activity context with the Application context, but it didn't help).
I'm using using Frgaments and ActionBarSherlock, and my Activity extends SlidingFragmentActivity (That's why i'm using the application context, which doesn't help).
Edit - This is the code of the service i'm trying to start -
public class ScheduleService extends Service {
/**
* Class for clients to access
*/
public class ServiceBinder extends Binder {
public ScheduleService getService() {
return ScheduleService.this;
}
}
#Override
public int onStartCommand(Intent intent, int flags, int startId) {
Log.i("ScheduleService", "Received start id " + startId + ": " + intent);
// We want this service to continue running until it is explicitly stopped, so return sticky.
return START_STICKY;
}
#Override
public IBinder onBind(Intent intent) {
return mBinder;
}
// This is the object that receives interactions from clients. See
private final IBinder mBinder = new ServiceBinder();
/**
* Show an alarm for a certain date when the alarm is called it will pop up a notification
*/
public void setAlarm(Calendar c) {
// This starts a new thread to set the alarm
// You want to push off your tasks onto a new thread to free up the UI to carry on responding
new AlarmTask(this, c).run();
}
}
Any help will be appreciated . Thanks.

What is the fully qualified class-name of ScheduleService (i.e. including the full package-name)?
I'm asking this, because in your AndroidManifest.xml file, your service's name is .Notifications.ScheduleService, which seems a bit odd:
This tells me that either
The (last part of the) package-name contains a upper-case
character... not so good.
I would expect .notifications.ScheduleService instead, if this is the case.
The ScheduleService is defined within a file called Notifications.java.
I would expect .Notifications$ScheduleService instead, if this is the case (dollar sign instead of period).

Do you mean bindService() returns false? onBind() returns IBinder type.
Keep in mind that service binding takes some time. If you want to perform some action after binding is done you can perform it in the onServiceConnected() method.
public void onServiceConnected(ComponentName className, IBinder service) {
mBoundService = ((ScheduleService.ServiceBinder) service).getService();
Calendar c = new Calendar();
mBoundService.setAlarm(c);
}
If you need more guidance on this you need to show us your Activity code.

Why do you use the application context to bind the service?
The method bindService is called through the ContextWrapper. It might not be the issue but I'd share contexts across the place where you bind the service and where you have the connection.
In your case instead of
boolean test = getApplicationContext().bindService(new Intent(this, ScheduleService.class), mConnection, Context.BIND_AUTO_CREATE);
I'd do the following
boolean test = bindService(new Intent(this, ScheduleService.class), mConnection, Context.BIND_AUTO_CREATE);
Or if you want to keep a global context within the application, move everything to your Application file and call it similarly the same way suggested above.
The issue can also be on the package name of your app and the declaration of your service in your manifest. If you are unsure make sure to give the global route to your service in the manifest.

Android: Getting a variable from my running service

My activity starts a Service, and when I close my app, the service continues to run.
OK, that's right. But when I open my application again, in the activity, I need to know the value of a public variable defined on the running Service(class) that I've started previously.
How can I do that?
Thanks

If you are binding your Activity to the Service, you should have an implementation of the Binder interface in your Service, e.g.
public class ServiceBinder extends Binder {
public MyService getService() {
return MyService.this;
}
}
In your Activity, create a new ServiceConnection class which will be used to give you access to your Service:
private ServiceConnection mConnection = new ServiceConnection() {
public void onServiceConnected(ComponentName className, IBinder service) {
mMyService = ((MyService.ServiceBinder)service).getService();
}
public void onServiceDisconnected(ComponentName className) {
mMyService = null;
}
};
Here the member variable mMyService will give you access to all public members of your Service class.
To create the connection, implement doBindService and doUnbindService in your Activity:
void doBindService() {
bindService(new Intent(this, MyService.class), mConnection, Context.BIND_AUTO_CREATE);
}
void doUnbindService() {
// Detach our existing connection.
unbindService(mConnection);
}
Hope this helps!

If you don't call unbindService, your activity still have connection to service and you can simply check the variable through the service's method.

You could use messenger.
As per android website
A messenger is reference to a Handler, which others can use to send messages to it. This allows for the implementation of message-based communication across processes, by creating a Messenger pointing to a Handler in one process, and handing that Messenger to another process.