Develop Reference

How to keep a local service running in between tabs?

I am currently working on a Pedometer application. At first, I started with one activity, the PedometerActivity. This activity started the service that is supposed to run in the background, and binds to it. The code is long so I'll just give sections of what I think will help in my question.
//Bind service
private ServiceConnection mServiceConnection = new ServiceConnection() {
public void onServiceConnected(ComponentName className, IBinder service) {
//binder to communicate with the service
PedometerService.PedometerBinder mBinder = (PedometerService.PedometerBinder)service;
mPedometerService = mBinder.getService();
mPedometerService.registerCallback(mCallback);
}
public void onServiceDisconnected(ComponentName className) {
mPedometerService = null;
}
};
private void startPedometerService() {
if (!isPedometerService) {
Log.v(TAG, "Start service");
isPedometerService = true;
//start service
Intent intent = new Intent(getApplicationContext(),
PedometerService.class);
startService(intent);
}
}
//Bind to the service
private void bindPedometerService() {
Log.i(TAG, "Bind service");
Intent intent = new Intent(PedometerActivity.this, PedometerService.class);
bindService(intent, mServiceConnection,
Context.BIND_AUTO_CREATE + Context.BIND_DEBUG_UNBIND);
}
//close connection with service
private void unbindPedometerService() {
Log.i(TAG, "Unbind service");
unbindService(mServiceConnection);
}
//Stop the service that had been started
private void stopPedometerService() {
Log.i(TAG, "Stop service");
if (mPedometerService != null) {
//stop service
Intent intent = new Intent(PedometerActivity.this, PedometerService.class);
stopService(intent);
isPedometerService = false;
}
}
#Override
public void onResume() {
Log.i(TAG, "onResume");
super.onResume();
startPedometerService();
bindPedometerService();
}
#Override
public void onStop() {
super.onStop();
Log.i(TAG, "onStop");
stopPedometerService();
}
public void onDestroy() {
super.onDestroy();
unbindPedometerService();
stopPedometerService();
}
In the service class that extends Service
/*Local service binding*/
public class PedometerBinder extends Binder {
public PedometerService getService() {
return PedometerService.this;
}
}
/*A client is binding to the service with bindService()
* Returns the IBinder object received in
* ServiceConnection.onServiceConnected(ComponentName,IBinder)*/
#Override
public IBinder onBind(Intent intent) {
return new PedometerBinder();
}
I then modified my application to have tablayout with 3 tabs hence 3 fragments. I pasted the code from PedometerActivity into PedometerFragment and modified it
//Bind service
private ServiceConnection mServiceConnection = new ServiceConnection() {
public void onServiceConnected(ComponentName className, IBinder service) {
//binder to communicate with the service
PedometerService.PedometerBinder mBinder = (PedometerService.PedometerBinder)service;
mPedometerService = mBinder.getService();
mPedometerService.registerCallback(mCallback);
}
public void onServiceDisconnected(ComponentName className) {
mPedometerService = null;
}
};
private void startPedometerService() {
if (!isPedometerService) {
Log.v(TAG, "Start service");
isPedometerService = true;
//start service
Intent intent = new Intent(getActivity().getApplicationContext(),
PedometerService.class);
getActivity().startService(intent);
}
}
//Bind to the service
private void bindPedometerService() {
Log.i(TAG, "Bind service");
Intent intent = new Intent(getActivity(), PedometerService.class);
getActivity().bindService(intent, mServiceConnection,
Context.BIND_AUTO_CREATE + Context.BIND_DEBUG_UNBIND);
}
//close connection with service
private void unbindPedometerService() {
Log.i(TAG, "Unbind service");
getActivity().unbindService(mServiceConnection);
}
//Stop the service that had been started
private void stopPedometerService() {
Log.i(TAG, "Stop service");
if (mPedometerService != null) {
//stop service
Intent intent = new Intent(getActivity(), PedometerService.class);
getActivity().stopService(intent);
isPedometerService = false;
}
}
#Override
public void onResume() {
Log.i(TAG, "onResume");
super.onResume();
startPedometerService();
bindPedometerService();
}
#Override
public void onStop() {
super.onStop();
Log.i(TAG, "onStop");
stopPedometerService();
}
public void onDestroy() {
super.onDestroy();
unbindPedometerService();
stopPedometerService();
}
The problem is am having trouble keeping the service running when I switch between tabs. I am using FragmentStatePagerAdapter and therefore when I navigate to the last tab, the first fragment (PedometerFragment) is unloaded. I have been able to save other variables in onSaveInstanceState but this does not seem to help since everything is restarted all over again.

You're using startService, so even if your bound components get destroyed, the service shouldn't be stopped. However, you're explicitly calling stopPedometerService() in onStop(), which is called when your fragment is no longer started.
Try simply removing stopPedometerService() from onStop() andonDestroy() in your fragments.
See: https://developer.android.com/reference/android/support/v4/app/FragmentStatePagerAdapter.html
This version of the pager is more useful when there are a large number
of pages, working more like a list view. When pages are not visible to
the user, their entire fragment may be destroyed, only keeping the
saved state of that fragment.

You need to bind service in the Activity class. Then you can use it from any attached Fragment via interface or public methods.

Wait in activity?

I have a class that has a service:
private ServiceConnection conn = new ServiceConnection() {
#Override
public void onServiceConnected(ComponentName name, IBinder service) {
service = ((MyService.LocalBinder)service).getService();
isBound = true;
}
#Override
public void onServiceDisconnected(ComponentName name) {
service = null;
isBound = false;
}
};
I also have this method:
public boolean isBound() {
return isBound;
}
In my activity I create an instance of the class. However, the service does not connected immediately.
In the activity, how can I wait the isBound() returns true without blocking the activity?

I am afraid you can't. By the way, you can also notify the world that your service has correctly connected with a BroadcastReceiver

In your service class send broadcast:
Intent intent=new Intent();
intent.setAction("com.intent.service.connected");
sendBroadcast(intent);
In your activity catch the intent:
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
IntentFilter filter = new IntentFilter("com.intent.service.connected");
this.registerReceiver(new Receiver(), filter);
}
private class Receiver extends BroadcastReceiver {
#Override
public void onReceive(Context arg0, Intent arg1) {
// your codes
}
}

My background music service stops when I load a new activity. Am I connecting or binding wrong?

I'm trying to add background music to my game and I thought I could persist it across activities by starting the service and then just connecting and binding to it in different activities in order to control it. But my music stops playing when I try to establish a connection from my second activity. I'm very new to working with services, so I apologize for any simple mistakes.
From my MusicService class (extends Service)
private final IBinder mBinder = new ServiceBinder();
MediaPlayer mPlayer;
private int length = 0;
public static boolean STOP_ON_DESTROY = true;
// Binder subclass. Allows access from clients to the server
public class ServiceBinder extends Binder {
MusicService getService(){
return MusicService.this;
}
}
public MusicService() {}
#Override
public IBinder onBind(Intent intent) {
return mBinder;
}
#Override
public void onCreate(){
super.onCreate();
}
#Override
public int onStartCommand (Intent intent, int flags, int startId)
{
return START_STICKY;
}
public boolean isPlaying(){
if(mPlayer != null){
return mPlayer.isPlaying();
}
return false;
}
public void stopMusic()
{
if(mPlayer != null){
if(mPlayer.isPlaying()) {
mPlayer.stop();
mPlayer.release();
mPlayer = null;
}
System.out.println("stopMusic service fn");
}
}
This is the code I call in both my Main and secondary activities in order to interact with the service. The music stops during the connectToMusicService function in the secondary activity. The Main activity works great.
onCreate(){....
startMusicService();
MusicService.STOP_ON_DESTROY = true;
}
private void startMusicService() {
Intent musicIntent = new Intent();
musicIntent.setClass(getApplicationContext(), MusicService.class);
startService(musicIntent);
}
#Override
public void onStart(){
super.onStart();
// establish connection for binding to the service
connectToMusicService();
// bind to the service
bindToMusicService();
}
private void bindToMusicService() {
Intent intent = new Intent(this, MusicService.class);
bindService(intent, myServiceConnection, Context.BIND_AUTO_CREATE);
MusicService.STOP_ON_DESTROY = true;
}
private void connectToMusicService() {
myServiceConnection = new ServiceConnection() {
#Override
public void onServiceConnected(ComponentName name, IBinder service) {
MusicService.ServiceBinder binder = (MusicService.ServiceBinder) service;
mService = binder.getService();
if(!mService.isPlaying())
mService.startMusic();
isServiceBound = true;
}
#Override
public void onServiceDisconnected(ComponentName name) {
System.out.println("Service disconnected from main");
isServiceBound = false;
}
};
}
The only thing I do during my Main activity's onStop is
#Override
public void onStop(){
super.onStop();
if(mService != null) {
if (MusicService.STOP_ON_DESTROY) {
mService.stopMusic();
}
}
}
UPDATE: I got it working. My issue wasn't with service binding at all. It was with static STOP_ON_DESTROY variable I was using to manage whether the music should stop when leaving an activity. I cleaned that up and all is good now. Thanks!

First of all, do you need to bind at all? Or could starting the service be enough? Started services run until you stop them (except if killed by the system when resources are scarce). I am not sure there's any point binding from each of your activities.
Btw if your service should run and play music also when your activities are closed, consider making it a foreground service.

bind/unbind service example (android)

can you give me a simple example of an application with background service which uses bind/unbind methods to start and stop it? I was googling for it for a half-hour, but those examples use startService/stopService methods or are very difficult for me. thank you.

You can try using this code:
protected ServiceConnection mServerConn = new ServiceConnection() {
#Override
public void onServiceConnected(ComponentName name, IBinder binder) {
Log.d(LOG_TAG, "onServiceConnected");
}
#Override
public void onServiceDisconnected(ComponentName name) {
Log.d(LOG_TAG, "onServiceDisconnected");
}
}
public void start() {
// mContext is defined upper in code, I think it is not necessary to explain what is it
mContext.bindService(intent, mServerConn, Context.BIND_AUTO_CREATE);
mContext.startService(intent);
}
public void stop() {
mContext.stopService(new Intent(mContext, ServiceRemote.class));
mContext.unbindService(mServerConn);
}

Add these methods to your Activity:
private MyService myServiceBinder;
public ServiceConnection myConnection = new ServiceConnection() {
public void onServiceConnected(ComponentName className, IBinder binder) {
myServiceBinder = ((MyService.MyBinder) binder).getService();
Log.d("ServiceConnection","connected");
showServiceData();
}
public void onServiceDisconnected(ComponentName className) {
Log.d("ServiceConnection","disconnected");
myService = null;
}
};
public Handler myHandler = new Handler() {
public void handleMessage(Message message) {
Bundle data = message.getData();
}
};
public void doBindService() {
Intent intent = null;
intent = new Intent(this, BTService.class);
// Create a new Messenger for the communication back
// From the Service to the Activity
Messenger messenger = new Messenger(myHandler);
intent.putExtra("MESSENGER", messenger);
bindService(intent, myConnection, Context.BIND_AUTO_CREATE);
}
And you can bind to service by ovverriding onResume(), and onPause() at your Activity class.
#Override
protected void onResume() {
Log.d("activity", "onResume");
if (myService == null) {
doBindService();
}
super.onResume();
}
#Override
protected void onPause() {
//FIXME put back
Log.d("activity", "onPause");
if (myService != null) {
unbindService(myConnection);
myService = null;
}
super.onPause();
}
Note, that when binding to a service only the onCreate() method is called in the service class.
In your Service class you need to define the myBinder method:
private final IBinder mBinder = new MyBinder();
private Messenger outMessenger;
#Override
public IBinder onBind(Intent arg0) {
Bundle extras = arg0.getExtras();
Log.d("service","onBind");
// Get messager from the Activity
if (extras != null) {
Log.d("service","onBind with extra");
outMessenger = (Messenger) extras.get("MESSENGER");
}
return mBinder;
}
public class MyBinder extends Binder {
MyService getService() {
return MyService.this;
}
}
After you defined these methods you can reach the methods of your service at your Activity:
private void showServiceData() {
myServiceBinder.myMethod();
}
and finally you can start your service when some event occurs like _BOOT_COMPLETED_
public class MyReciever extends BroadcastReceiver {
public void onReceive(Context context, Intent intent) {
String action = intent.getAction();
if (action.equals("android.intent.action.BOOT_COMPLETED")) {
Intent service = new Intent(context, myService.class);
context.startService(service);
}
}
}
note that when starting a service the onCreate() and onStartCommand() is called in service class
and you can stop your service when another event occurs by stopService()
note that your event listener should be registerd in your Android manifest file:
<receiver android:name="MyReciever" android:enabled="true" android:exported="true">
<intent-filter>
<action android:name="android.intent.action.BOOT_COMPLETED" />
</intent-filter>
</receiver>

First of all, two things that we need to understand,
Client
It makes request to a specific server
bindService(new Intent("com.android.vending.billing.InAppBillingService.BIND"),
mServiceConn, Context.BIND_AUTO_CREATE);
here mServiceConn is instance of ServiceConnection class(inbuilt) it is actually interface
that we need to implement with two (1st for network connected and 2nd network not connected) method to monitor network connection state.
Server
It handles the request of the client and makes replica of its own which is private to client only who send request and this raplica of server runs on different thread.
Now at client side, how to access all the methods of server?
Server sends response with IBinder Object. So, IBinder object is our handler which accesses all the methods of Service by using (.) operator.
.
MyService myService;
public ServiceConnection myConnection = new ServiceConnection() {
public void onServiceConnected(ComponentName className, IBinder binder) {
Log.d("ServiceConnection","connected");
myService = binder;
}
//binder comes from server to communicate with method's of
public void onServiceDisconnected(ComponentName className) {
Log.d("ServiceConnection","disconnected");
myService = null;
}
}
Now how to call method which lies in service
myservice.serviceMethod();
Here myService is object and serviceMethod is method in service.
and by this way communication is established between client and server.

Sticky Service Management

I've got a Sticky Service (returns START_STICKY from onStartCommand) which executes some code in an AsyncTask, but I'm having some problems with how and when to start, bind, stop, unbind. I only want the service around whilst the parent activity is alive, I don't want it hanging around in the background when the app has been closed, but I need the service to survive an orientation change. I currently don't need the service to be active for the entire duration of the activity being active, so I call stopSelf() after the main work is done in my AsyncTask in the Service and then start the Service again when needed. Sometimes I'll need to interrupt the work the service is doing, cancel the AsyncTask and start again with different data. The problem is that no matter what I do - I can't seem to get it solid throughout all the different possible scenarios. Can anyone have a look through and tell me what I'm doing wrong?
My Service is :
public class ChordCalculatorService extends Service {
private final IBinder mBinder = new LocalBinder();
private AsyncTask<SearchData, SearchStatusData, List<Item>> currentTask;
#Override
public void onCreate() {}
#Override
public int onStartCommand(Intent intent, int flags, int startId) {
// We want this service to continue running until it is explicitly
// stopped, so return sticky.
return START_STICKY;
}
/**
* Class for clients to access. Because we know this service always runs in
* the same process as its clients, we don't need to deal with IPC.
*/
public class LocalBinder extends Binder {
public ChordCalculatorService getService() {
return ChordCalculatorService.this;
}
}
#Override
public void onDestroy() {
super.onDestroy();
}
#Override
public IBinder onBind(Intent intent) {
return mBinder;
}
public SearchData getSearchData() {
return searchData;
}
public void startWork() {
if (currentTask != null && currentTask.getStatus() == Status.RUNNING) {
currentTask.cancel(true);
}
if(searchData != null) {
Worker task = new Worker();
currentTask = task.execute(new SearchData[] { searchData });
} else {
Message msg = handler.obtainMessage(ERROR, "No search data set");
handler.sendMessage(msg);
}
}
class Worker extends AsyncTask<SearchData, SearchStatusData, List<Item>> {
// ... code ...
#Override
protected void onPostExecute(List<Item> result) {
Message msg = handler.obtainMessage(COMPLETE, new StatusData(Status.STATUS_FINISHED, result));
handler.sendMessage(msg);
stopSelf();
}
}
}
Currently I have the Service being started when my custom View is created:
public class MyCustomView extends BasicFretBoardView {
private ServiceConnection conn;
private MyService myService;
private boolean isServiceStarted;
private boolean isServiceBound;
public MyCustomView(Context context, AttributeSet attr) {
super(context, attr);
startService();
}
public void startService() {
Intent serviceIntent = new Intent(getContext(), MyService.class);
conn = new ServiceConnection() {
#Override
public void onServiceConnected(ComponentName name, IBinder service) {
myService = ((LocalBinder) service).getService();
myService.registerHandler(serviceHandler);
}
#Override
public void onServiceDisconnected(ComponentName name) {
myService = null;
}
};
// Explicitly start the service. Don't use BIND_AUTO_CREATE, since it
// causes an implicit service stop when the last binder is removed.
getContext().startService(serviceIntent);
getContext().bindService(serviceIntent, conn, 0);
isServiceStarted = true;
isServiceBound = true;
}
public void stopService() {
if (isServiceStarted) {
Intent serviceIntent = new Intent(getContext(), MyService.class);
getContext().stopService(serviceIntent);
isServiceStarted = false;
}
unBindService();
}
public void unBindService() {
if(isServiceBound) {
getContext().unbindService(conn);
isServiceBound = false;
}
}
// gets called based on some user interaction
private void startServiceWork() {
if(!isServiceStarted) {
startService();
} else {
myService.cancelCalcalation();
}
myService.setData(data);
myService.startWork();
}
}
and stopping the service is handled in the Activity:
public class CustomChordActivity extends Activity {
// ... code ...
#Override
public void onBackPressed() {
super.onBackPressed();
}
#Override
protected void onPause() {
if(isFinishing()) {
chordsView.stopService();
}
super.onPause();
}
#Override
protected void onStop() {
super.onStop();
}
#Override
protected void onDestroy() {
chordsView.unBindService();
super.onDestroy();
}
#Override
protected void finalize() throws Throwable {
super.finalize();
}
}

It seems that you want your task to run on demand, maybe an IntentService would be a more suitable option. When you need work to be done, (startServiceWork()), you just start the service and that kicks off your AsyncTask. The service will then finish after the task has finished.
Now, regarding orientation changes, you would have to implement a Broadcast Receiver whose intent filter is "android.intent.action.CONFIGURATION_CHANGED". (I assume that you want the service to do work when the orientation changes) Place the Broadcast Receiver, within your activity/main ui thread. This will in effect make the hosting process of your Broadcast Receiver to be the main application process making it safer to start the service from within the Broadcast Receiver.