Develop Reference

Why can't I bind to my foreground service twice from the same object?

I have an object in app A that implements IServiceConnection which binds to a foreground Service in a different app (app B):
public class MyServiceConnection : Java.Lang.Object, IServiceConnection
{
private IBinder _binder;
private TaskCompletionSource<bool> _connectTcs;
public MyServiceConnection()
{
BeginConnect();
}
public void BeginConnect() => ConnectAsync().ContinueWith(EndConnect);
public Task<bool> ConnectAsync(CancellationToken ct = default)
{
if (_connectTcs?.IsCompleted ?? true)
{
_connectTcs = new TaskCompletionSource<bool>();
ct.Register(() => _connectTcs.TrySetCanceled(ct));
var package = "com.sample.appb";
var componentName = new Componentname(package, $"{package}.ServiceInB");
var service = new Intent().SetComponent(componentName);
if (Build.VERSION.SdkInt >= BuildVersionCodes.O)
{
Application.Context.StartForegroundService(service);
}
else
{
Application.Context.StartService(service);
}
Application.Context.BindService(service, this, Bind.AutoCreate);
}
return await _connectTcs;
}
private void EndConnect(Task task)
{
// handle task result
}
public void OnServiceConnected(ComponentName name, IBinder service)
{
_binder = service;
}
public void OnServiceDisconnected(ComponentName name)
{
_binder = null;
}
// methods that are called on the service
}
When the object is created, I bind to the Service and it is successful. When app B crashes or I call am force-stop on app B, OnServiceDisconnected() gets called, which is expected. I handle the lost connection by connecting again, but on the second connection OnServiceConnected() never gets called, so I never get my IBinder object to call methods on. If I restart app A I can perform a single bind again. How do I properly get the Service binder multiple times during one run time?

To solve this issue, I split the original object into two objects: One that inherits from IServiceConnection and holds the IBinder from the service, and another that holds instances of these. When the holder needs to connect, it first disposes any held instance of the IServiceConnection, then calls Context.BindService() with a new instance. When the holder needs to disconnect, it calls Context.UnbindService(), then disposes the IServiceConnection instance.

How to use interface to communicate between activities after process death?

I am building an SDK and need to implement callbacks between activities, without actually finish an activity. I previously used onActivityResult to provide results back to caller activity. However, this closes activity and I need to deliver callback, without finishing activity from SDK. My current implementation:
fun initializeSDK(){
SDK.getInstance().initialize(resultsCallbackImpl)
}
val resultsCallbackImpl:ResultsCallback = object : ResultsCallback {
override fun response1() {
}
override fun response2() {
}
};
For example, the client calls initializeSDK() from his activity after the button click. Then the client passes interface as parameter, which is set as a property in SDK singleton. Then I use that interface to return results.
The problem occurs after process death. The interface becomes null, because it is not serialized and I can't return callback to client anymore. How should I edit my code to tackle this issue? Is it even possible?
I know that client can initialize SDK in the application class, then it will be re-set after process death. However, such an approach will result in difficulty for the client to communicate results back to activity from application class.

Update:
Do a right click on the project tree and add a new AIDL file called IMyAidlInterface.aidl:
package com.test.aidlsample;
import com.test.aidlsample.MyData;
interface IMyAidlInterface {
List<MyData> getData(long id);
}
If you need to return objects to your client you need to declare and define them as parcelable and import them in aidl file too, here is the MyData.aidl that should be beside the other aidl file:
package com.test.aidlsample;
// Declare MyData so AIDL can find it and knows that it implements
// the parcelable protocol.
parcelable MyData;
and this is MyData.java in the java folder:
public class MyData implements Parcelable {
private long productId;
private String productName;
private long productValue;
public MyData(long productId, String productName, long productValue) {
this.productId = productId;
this.productName = productName;
this.productValue = productValue;
}
#Override
public int describeContents() {
return 0;
}
#Override
public void writeToParcel(Parcel dest, int flags) {
dest.writeLong(this.productId);
dest.writeString(this.productName);
dest.writeLong(this.productValue);
}
protected MyData(Parcel in) {
this.productId = in.readLong();
this.productName = in.readString();
this.productValue = in.readLong();
}
public static final Parcelable.Creator<MyData> CREATOR = new Parcelable.Creator<MyData>() {
#Override
public MyData createFromParcel(Parcel source) {
return new MyData(source);
}
#Override
public MyData[] newArray(int size) {
return new MyData[size];
}
};
}
Now build the project so Stub class gets built. After a successful build continue with the service:
public class SdkService extends Service {
private IMyAidlInterface.Stub binder = new IMyAidlInterface.Stub() {
#Override
public List<MyData> getData(long id) throws RemoteException {
//TODO: get data from db by id;
List<MyData> data = new ArrayList<>();
MyData aData = new MyData(1L, "productName", 100L);
data.add(aData);
return data;
}
};
#Nullable
#Override
public IBinder onBind(Intent intent) {
return binder;
}
}
and add the service to the sdk manifest. If you are adding sdk as a dependency to the client like: implementation project(':sdk') you don't need to add AIDL files to client. If not, you have to add them and build the client application. Now, only remains to implement the client activity:
public class MainActivity extends AppCompatActivity {
IMyAidlInterface mService;
/**
* Class for interacting with the main interface of the service.
*/
private ServiceConnection mConnection = new ServiceConnection() {
public void onServiceConnected(ComponentName className,
IBinder service) {
// This is called when the connection with the service has been
// established, giving us the service object we can use to
// interact with the service. We are communicating with our
// service through an IDL interface, so get a client-side
// representation of that from the raw service object.
mService = IMyAidlInterface.Stub.asInterface(service);
try {
List<MyData> data = mService.getData(1L);
updateUi(data);
} catch (RemoteException e) {
// In this case the service has crashed before we could even
// do anything with it; we can count on soon being
// disconnected (and then reconnected if it can be restarted)
// so there is no need to do anything here.
}
}
public void onServiceDisconnected(ComponentName className) {
// This is called when the connection with the service has been
// unexpectedly disconnected -- that is, its process crashed.
mService = null;
}
};
private void updateUi(List<MyData> data) {
//TODO: Update UI here
}
#Override
protected void onResume() {
if (mService == null) {
Intent serviceIntent = new Intent();
//CAREFUL: serviceIntent.setComponent(new ComponentName("your.client.package", "your.sdk.service.path"));
serviceIntent.setComponent(new ComponentName("com.test.sampleclient", "com.test.aidlsample.SdkService"));
bindService(serviceIntent, mConnection, Context.BIND_AUTO_CREATE);
} else {
try {
updateUi(mService.getData(1L));
} catch (RemoteException e) {
e.printStackTrace();
}
}
super.onResume();
}
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
}
}
every time your client activity gets visibility, it gets data from sdk service. Just build your logic over this template. In sdk activity save data to a database and in service query them from database. I've used simple parameters in this sample.
I assumed your sdk is a library in the client app. If not, you need to do some small modifications maybe. And as I mentioned before you can find more details here: Android Interface Definition Language (AIDL). There are lots of samples and even more Q/A here in the SO on the subject. Good luck.
Original: You need to get callbacks from an activity that is currently invisible since your SDK activity is in front, right? To do that you can create a database for your SDK, persist data to your database and get data via an AIDL in the starting activity:
SdkService sdkService;
CallbackData callbackData
private ServiceConnection mConnection = new ServiceConnection() {
// Called when the connection with the service is established
public void onServiceConnected(ComponentName className, IBinder service) {
sdkService = SdkService.Stub.asInterface(service);
}
// Called when the connection with the service disconnects unexpectedly
public void onServiceDisconnected(ComponentName className) {
Log.e(TAG, "Service has unexpectedly disconnected");
sdkService = null;
}
};
in onCreate:
Intent i = new Intent()
i.setClassName("your.sdk.packageName", "your.sdk.service.path.and.name");
bindService(i, mConnection, Context.BIND_AUTO_CREATE);
and in whenever needed:
if(sdkService != null){
callbackData = sdkService.getCallbacks();
updateUI();
}
Just be careful getting a binder is an async job so if you call bindService and right after call sdkService.getCallbackData you get a NullPointerException. So you might want to move getCallbacks and updateUI inside the onServiceConnected and call bindService in onResume so every time activity becomes visible you would check if there is CallbackData so you can update your UI or whatever.

You cannot use interfaces directly to communicate between activities.
As soon as you start a new activity and new activity becomes visible android OS can kill 1st activity anytime (you can try this with a flag inside developer option "Don't keep activities"). So user of your SDK will complain about certain random "null pointer exception".
So, Now if you want to share data between current and previous screen, you might have to rethought your solution using Fragments.
Exposing your UI using a fragment and communicating back your result to activity which then would update proper fragment which needs the data.
I faced similar issue in one existing app which I was asked to fix. I switched entire app to fragments and single activity, first to release a hot fix.

The problem occurs after process death. The interface becomes null, because it is not serialised and I can't return callback to client anymore. How should I edit my code to tackle this issue? Is it even possible?
This is not possible. If the client process dies, all of its executing code - including your SDK - gets wiped away.
I know that client can initialise SDK in the application class, then it will be re-set after process death. However, such approach will result in difficulty for client to communicate results back to activity from application class.
So what? If the client Activity is restarted, it should call the SDK again to set a new callback instance which you can use from that point forward.

You can use a sharedviewmodel that is bound to both activities; have a mutablelivedata variable that you can observe from the two activities.
ideally on the first activity you can just put the value inside the mutablelivedata variable. Then on the second activity get the activity.
Follow the following link to give you a guideline.
ViewModel Overview

Binding and starting a service when application starts

I have a service in Android that encapsulates a framework that has a start method. The service boils down to something like this, many things omitted:
public class MyService extends Service {
private IBinder thisBinder;
public MyService(){
thisBinder = new LocalBinder();
}
#Override
public IBinder onBind(Intent intent) {
return thisBinder;
}
public void start(Map<String, Object> options)
{
getDriverManager().start(options);
}
}
I also have a bridging class that makes calls to the service:
public class MyServiceBridge implements ServiceConnection {
private boolean started = false;
private boolean bound = false;
private MyService myService;
public MyServiceBridge(Context context){
this.context = context;
}
public void bindService(){
Intent intent = new Intent(getContext(), MyService.class);
getContext().bindService(intent, this, getContext().BIND_AUTO_CREATE);
getContext().startService(intent);
}
// Here's a sample call, and the one that is relevant
public void start(Map<String, Object> options){
setOptions(options);
if(bound == true){
getMyService().start(options);
}
else{
started = true;
}
}
}
I call the bridge's start method in order to run the service. This works fine, except in this particular situation (so far). The MyApplication class calls the bridge's start method on onCreate:
public class MyApplication extends Application {
#Override
public void onCreate() {
super.onCreate();
getServiceBridge().start(null);
}
}
This, according to the docs is "Called when the application is starting, before any activity, service, or receiver objects (excluding content providers) have been created.". Indeed it appears to be so, because the service does not start, and instead starts when I close the app (odd, at least). This works if I move the call to an activity's onCreate method, but that's not ideal because I can also stop the service, and I want the service to run for the lifetime of the app. That is, the service should start when the app starts and stop when the app terminates. Does this make sense? Is there another way to do this?

In my opinion, you did a good job when you decided to run service in Application onCreate. but it is strange to hear that service is started when you close the app.
I have done this several times, and service starts in application onCreate which must be called.
Have you checked if your application is alive and run in background? Please make sure that you killed you application before testing. Use Task Killer or something like that, to be sure that application is always freshly started.
Sadly, Android does not have appropriate mechanism to notify you when application is exited, because it is still alive until system decides to kill it and free resources.

How to hold an Object as long as a service live?

I have an Object that i use in all my activities which holds a lot of complex data in it, it would be quite an hassle to use Android framework of saving the object state and passing it around from activity to activity, so i thought it would be possible to make a Singleton that manages this object and makes it live as long as the application lives.
Tried to use regular Java Singleton scheme, with normal class and normal static instance, but the instance becomes null after a while (which is very confusing, why would an Object that is still referenced be turned to null and garbage collected?). so i decided to flow with Android designers and created a Service to manage this Object, the Service looks something like that :
public class DataService extends Service {
private Data data;
private static DataService instance;
#Override
public void onCreate() {
instance = this;
data= new Data(...);
instance.data.addProgressListener(listener);
(new Thread() {
#Override
public void run() {
data.doInitProgress();
listener = null;
};
}).start();
}
public static void listenToInitDataProcess(final ProgressBar progressBar,final Runnable onDone) {
listener = new ProgressListener() {
private int progress;
private int max;
#Override
public void onUpdateProgress(final long i) {
progressBar.setProgress(progress+=i);
}
#Override
public void onProgressEndComputed(final long n) {
progressBar.setMax(max=(int) n);
}
#Override
public void onDone() {
progressBar.setProgress(max);
onDone.run();
}
};
if (instance!=null) instance.data.addProgressListener(listener);
}
public static Data getData() {
return instance.data;
}
#Override
public IBinder onBind(Intent arg0) {
return null;
}
}
now the problem with that is that after a while that the app is on i get NPE caused by instance is null... notice that i was listenning to the data object creation and i was trying to get it only after it was once inited, so no way that instance was suppose to be null...
how to do this right then?

If you want an Object that lives as long as your application lives (i.e. as long as its process is not killed by OS) you can extend android.app.Application, put your 'global' data there and use that subclass as your app context (needs to be declared in manifest)
However many argue that singletons provide essentially the same result as custom context e.g.
Singletons vs. Application Context in Android?

but the instance becomes null after a while
First, understand Effective Java's singleton recommendations, and how something wouldn't become null:
// Singleton with public final field
public class Elvis {
public static final Elvis INSTANCE = new Elvis();
private Elvis() { ... }
public void leaveTheBuilding() { ... }
}
But a Service is different, since there is no public constructor there. So, first check if the Service is running (as referenced in this post: Check if Service is running from a Broadcast Receiver):
private boolean isMyServiceRunning(Context context) {
ActivityManager manager = (ActivityManager) context.getSystemService(Context.ACTIVITY_SERVICE);
for (RunningServiceInfo service : manager.getRunningServices(Integer.MAX_VALUE)) {
if (DataService.class.getName().equals(service.service.getClassName())) {
return true;
}
}
return false;
}
Then define some methods in your Service to return your needed state variables.

How to check if a service is running on Android?

How do I check if a background service is running?
I want an Android activity that toggles the state of the service -- it lets me turn it on if it is off and off if it is on.

I use the following from inside an activity:
private boolean isMyServiceRunning(Class<?> serviceClass) {
ActivityManager manager = (ActivityManager) getSystemService(Context.ACTIVITY_SERVICE);
for (RunningServiceInfo service : manager.getRunningServices(Integer.MAX_VALUE)) {
if (serviceClass.getName().equals(service.service.getClassName())) {
return true;
}
}
return false;
}
And I call it using:
isMyServiceRunning(MyService.class)
This works reliably, because it is based on the information about running services provided by the Android operating system through ActivityManager#getRunningServices.
All the approaches using onDestroy or onSometing events or Binders or static variables will not work reliably because as a developer you never know, when Android decides to kill your process or which of the mentioned callbacks are called or not. Please note the "killable" column in the lifecycle events table in the Android documentation.

I had the same problem not long ago. Since my service was local, I ended up simply using a static field in the service class to toggle state, as described by hackbod here
EDIT (for the record):
Here is the solution proposed by hackbod:
If your client and server code is part of the same .apk and you are
binding to the service with a concrete Intent (one that specifies the
exact service class), then you can simply have your service set a
global variable when it is running that your client can check.
We deliberately don't have an API to check whether a service is
running because, nearly without fail, when you want to do something
like that you end up with race conditions in your code.

Got it!
You MUST call startService() for your service to be properly registered and passing BIND_AUTO_CREATE will not suffice.
Intent bindIntent = new Intent(this,ServiceTask.class);
startService(bindIntent);
bindService(bindIntent,mConnection,0);
And now the ServiceTools class:
public class ServiceTools {
private static String LOG_TAG = ServiceTools.class.getName();
public static boolean isServiceRunning(String serviceClassName){
final ActivityManager activityManager = (ActivityManager)Application.getContext().getSystemService(Context.ACTIVITY_SERVICE);
final List<RunningServiceInfo> services = activityManager.getRunningServices(Integer.MAX_VALUE);
for (RunningServiceInfo runningServiceInfo : services) {
if (runningServiceInfo.service.getClassName().equals(serviceClassName)){
return true;
}
}
return false;
}
}

A small complement is:
My goal is to know wether a service is running without actualy running it if it is not running.
Calling bindService or calling an intent that can be caught by the service is not a good idea then as it will start the service if it is not running.
So, as miracle2k suggested, the best is to have a static field in the service class to know whether the service has been started or not.
To make it even cleaner, I suggest to transform the service in a singleton with a very very lazy fetching: that is, there is no instantiation at all of the singleton instance through static methods. The static getInstance method of your service/singleton just returns the instance of the singleton if it has been created. But it doesn't actualy start or instanciate the singleton itself. The service is only started through normal service start methods.
It would then be even cleaner to modify the singleton design pattern to rename the confusing getInstance method into something like the isInstanceCreated() : boolean method.
The code will look like:
public class MyService extends Service
{
private static MyService instance = null;
public static boolean isInstanceCreated() {
return instance != null;
}//met
#Override
public void onCreate()
{
instance = this;
....
}//met
#Override
public void onDestroy()
{
instance = null;
...
}//met
}//class
This solution is elegant, but it is only relevant if you have access to the service class and only for classes iside the app/package of the service. If your classes are outside of the service app/package then you could query the ActivityManager with limitations underlined by Pieter-Jan Van Robays.

You can use this (I didn't try this yet, but I hope this works):
if(startService(someIntent) != null) {
Toast.makeText(getBaseContext(), "Service is already running", Toast.LENGTH_SHORT).show();
}
else {
Toast.makeText(getBaseContext(), "There is no service running, starting service..", Toast.LENGTH_SHORT).show();
}
The startService method returns a ComponentName object if there is an already running service. If not, null will be returned.
See public abstract ComponentName startService (Intent service).
This is not like checking I think, because it's starting the service, so you can add stopService(someIntent); under the code.

/**
* Check if the service is Running
* #param serviceClass the class of the Service
*
* #return true if the service is running otherwise false
*/
public boolean checkServiceRunning(Class<?> serviceClass){
ActivityManager manager = (ActivityManager) getSystemService(ACTIVITY_SERVICE);
for (RunningServiceInfo service : manager.getRunningServices(Integer.MAX_VALUE))
{
if (serviceClass.getName().equals(service.service.getClassName()))
{
return true;
}
}
return false;
}

An extract from Android docs:
Like sendBroadcast(Intent), but if there are any receivers for
the Intent this function will block and immediately dispatch them
before returning.
Think of this hack as "pinging" the Service. Since we can broadcast synchronously, we can broadcast and get a result synchronously, on the UI thread.
Service
#Override
public void onCreate() {
LocalBroadcastManager
.getInstance(this)
.registerReceiver(new ServiceEchoReceiver(), new IntentFilter("ping"));
//do not forget to deregister the receiver when the service is destroyed to avoid
//any potential memory leaks
}
private class ServiceEchoReceiver extends BroadcastReceiver {
public void onReceive (Context context, Intent intent) {
LocalBroadcastManager
.getInstance(this)
.sendBroadcastSync(new Intent("pong"));
}
}
Activity
bool serviceRunning = false;
protected void onCreate (Bundle savedInstanceState){
LocalBroadcastManager.getInstance(this).registerReceiver(pong, new IntentFilter("pong"));
LocalBroadcastManager.getInstance(this).sendBroadcastSync(new Intent("ping"));
if(!serviceRunning){
//run the service
}
}
private BroadcastReceiver pong = new BroadcastReceiver(){
public void onReceive (Context context, Intent intent) {
serviceRunning = true;
}
}
The winner in many applications is, of course, a static boolean field on the service that is set to true in Service.onCreate() and to false in Service.onDestroy() because it's a lot simpler.

Another approach using kotlin. Inspired in other users answers
fun isMyServiceRunning(serviceClass: Class<*>): Boolean {
val manager = getSystemService(Context.ACTIVITY_SERVICE) as ActivityManager
return manager.getRunningServices(Integer.MAX_VALUE)
.any { it.service.className == serviceClass.name }
}
As kotlin extension
fun Context.isMyServiceRunning(serviceClass: Class<*>): Boolean {
val manager = this.getSystemService(Context.ACTIVITY_SERVICE) as ActivityManager
return manager.getRunningServices(Integer.MAX_VALUE)
.any { it.service.className == serviceClass.name }
}
Usage
context.isMyServiceRunning(MyService::class.java)

The proper way to check if a service is running is to simply ask it. Implement a BroadcastReceiver in your service that responds to pings from your activities. Register the BroadcastReceiver when the service starts, and unregister it when the service is destroyed. From your activity (or any component), send a local broadcast intent to the service and if it responds, you know it's running. Note the subtle difference between ACTION_PING and ACTION_PONG in the code below.
public class PingableService extends Service {
public static final String ACTION_PING = PingableService.class.getName() + ".PING";
public static final String ACTION_PONG = PingableService.class.getName() + ".PONG";
public int onStartCommand (Intent intent, int flags, int startId) {
LocalBroadcastManager.getInstance(this).registerReceiver(mReceiver, new IntentFilter(ACTION_PING));
return super.onStartCommand(intent, flags, startId);
}
#Override
public void onDestroy () {
LocalBroadcastManager.getInstance(this).unregisterReceiver(mReceiver);
super.onDestroy();
}
private BroadcastReceiver mReceiver = new BroadcastReceiver() {
#Override
public void onReceive (Context context, Intent intent) {
if (intent.getAction().equals(ACTION_PING)) {
LocalBroadcastManager manager = LocalBroadcastManager.getInstance(getApplicationContext());
manager.sendBroadcast(new Intent(ACTION_PONG));
}
}
};
}
public class MyActivity extends Activity {
private boolean isSvcRunning = false;
#Override
protected void onStart() {
LocalBroadcastManager manager = LocalBroadcastManager.getInstance(getApplicationContext());
manager.registerReceiver(mReceiver, new IntentFilter(PingableService.ACTION_PONG));
// the service will respond to this broadcast only if it's running
manager.sendBroadcast(new Intent(PingableService.ACTION_PING));
super.onStart();
}
#Override
protected void onStop() {
LocalBroadcastManager.getInstance(this).unregisterReceiver(mReceiver);
super.onStop();
}
protected BroadcastReceiver mReceiver = new BroadcastReceiver() {
#Override
public void onReceive (Context context, Intent intent) {
// here you receive the response from the service
if (intent.getAction().equals(PingableService.ACTION_PONG)) {
isSvcRunning = true;
}
}
};
}

I have slightly modified one of the solutions presented above, but passing the class instead of a generic string name, in order to be sure to compare strings coming out from the same method class.getName()
public class ServiceTools {
private static String LOG_TAG = ServiceTools.class.getName();
public static boolean isServiceRunning(Context context,Class<?> serviceClass){
final ActivityManager activityManager = (ActivityManager)context.getSystemService(Context.ACTIVITY_SERVICE);
final List<RunningServiceInfo> services = activityManager.getRunningServices(Integer.MAX_VALUE);
for (RunningServiceInfo runningServiceInfo : services) {
Log.d(Constants.TAG, String.format("Service:%s", runningServiceInfo.service.getClassName()));
if (runningServiceInfo.service.getClassName().equals(serviceClass.getName())){
return true;
}
}
return false;
}
}
and then
Boolean isServiceRunning = ServiceTools.isServiceRunning(
MainActivity.this.getApplicationContext(),
BackgroundIntentService.class);

I just want to add a note to the answer by #Snicolas. The following steps can be used to check stop service with/without calling onDestroy().
onDestroy() called: Go to Settings -> Application -> Running Services -> Select and stop your service.
onDestroy() not Called: Go to Settings -> Application -> Manage Applications -> Select and "Force Stop" your application in which your service is running. However, as your application is stopped here, so definitely the service instances will also be stopped.
Finally, I would like to mention that the approach mentioned there using a static variable in singleton class is working for me.

First of all you shouldn't reach the service by using the ActivityManager. (Discussed here)
Services can run on their own, be bound to an Activity or both. The way to check in an Activity if your Service is running or not is by making an interface (that extends Binder) where you declare methods that both, the Activity and the Service, understand. You can do this by making your own Interface where you declare for example "isServiceRunning()".
You can then bind your Activity to your Service, run the method isServiceRunning(), the Service will check for itself if it is running or not and returns a boolean to your Activity.
You can also use this method to stop your Service or interact with it in another way.

onDestroy isn't always called in the service so this is useless!
For example: Just run the app again with one change from Eclipse. The application is forcefully exited using SIG: 9.

Again, another alternative that people might find cleaner if they use pending intents (for instance with the AlarmManager:
public static boolean isRunning(Class<? extends Service> serviceClass) {
final Intent intent = new Intent(context, serviceClass);
return (PendingIntent.getService(context, CODE, intent, PendingIntent.FLAG_NO_CREATE) != null);
}
Where CODE is a constant that you define privately in your class to identify the pending intents associated to your service.

Below is an elegant hack that covers all the Ifs. This is for local services only.
public final class AService extends Service {
private static AService mInstance = null;
public static boolean isServiceCreated() {
try {
// If instance was not cleared but the service was destroyed an Exception will be thrown
return mInstance != null && mInstance.ping();
} catch (NullPointerException e) {
// destroyed/not-started
return false;
}
}
/**
* Simply returns true. If the service is still active, this method will be accessible.
* #return
*/
private boolean ping() {
return true;
}
#Override
public void onCreate() {
mInstance = this;
}
#Override
public void onDestroy() {
mInstance = null;
}
}
And then later on:
if(AService.isServiceCreated()){
...
}else{
startService(...);
}

Xamarin C# version:
private bool isMyServiceRunning(System.Type cls)
{
ActivityManager manager = (ActivityManager)GetSystemService(Context.ActivityService);
foreach (var service in manager.GetRunningServices(int.MaxValue)) {
if (service.Service.ClassName.Equals(Java.Lang.Class.FromType(cls).CanonicalName)) {
return true;
}
}
return false;
}

For the use-case given here we may simply make use of the stopService() method's return value. It returns true if there exists the specified service and it is killed. Else it returns false. So you may restart the service if the result is false else it is assured that the current service has been stopped. :) It would be better if you have a look at this.

The response of geekQ but in Kotlin class. Thanks geekQ
fun isMyServiceRunning(serviceClass : Class<*> ) : Boolean{
var manager = getSystemService(Context.ACTIVITY_SERVICE) as ActivityManager
for (service in manager.getRunningServices(Integer.MAX_VALUE)) {
if (serviceClass.name.equals(service.service.className)) {
return true
}
}
return false
}
The call
isMyServiceRunning(NewService::class.java)

In your Service Sub-Class Use a Static Boolean to get the state of the Service as demonstrated below.
MyService.kt
class MyService : Service() {
override fun onCreate() {
super.onCreate()
isServiceStarted = true
}
override fun onDestroy() {
super.onDestroy()
isServiceStarted = false
}
companion object {
var isServiceStarted = false
}
}
MainActivity.kt
class MainActivity : AppCompatActivity(){
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
setContentView(R.layout.activity_main)
val serviceStarted = FileObserverService.isServiceStarted
if (!serviceStarted) {
val startFileObserverService = Intent(this, FileObserverService::class.java)
ContextCompat.startForegroundService(this, startFileObserverService)
}
}
}

In kotlin you can add boolean variable in companion object and check its value from any class you want:
companion object{
var isRuning = false
}
Change it value when service is created and destroyed
override fun onCreate() {
super.onCreate()
isRuning = true
}
override fun onDestroy() {
super.onDestroy()
isRuning = false
}

For kotlin, you can use the below code.
fun isMyServiceRunning(calssObj: Class<SERVICE_CALL_NAME>): Boolean {
val manager = requireActivity().getSystemService(Context.ACTIVITY_SERVICE) as ActivityManager
for (service in manager.getRunningServices(Integer.MAX_VALUE)) {
if (calssObj.getName().equals(service.service.getClassName())) {
return true
}
}
return false
}

Inside TheServiceClass define:
public static Boolean serviceRunning = false;
Then In onStartCommand(...)
public int onStartCommand(Intent intent, int flags, int startId) {
serviceRunning = true;
...
}
#Override
public void onDestroy()
{
serviceRunning = false;
}
Then, call if(TheServiceClass.serviceRunning == true) from any class.

simple use bind with don't create auto - see ps. and update...
public abstract class Context {
...
/*
* #return {true} If you have successfully bound to the service,
* {false} is returned if the connection is not made
* so you will not receive the service object.
*/
public abstract boolean bindService(#RequiresPermission Intent service,
#NonNull ServiceConnection conn, #BindServiceFlags int flags);
example :
Intent bindIntent = new Intent(context, Class<Service>);
boolean bindResult = context.bindService(bindIntent, ServiceConnection, 0);
why not using? getRunningServices()
List<ActivityManager.RunningServiceInfo> getRunningServices (int maxNum)
Return a list of the services that are currently running.
Note: this method is only intended for debugging or implementing service management type user interfaces.
ps. android documentation is misleading i have opened an issue on google tracker to eliminate any doubts:
https://issuetracker.google.com/issues/68908332
as we can see bind service actually invokes a transaction via ActivityManager binder through Service cache binders - i dint track which service is responsible for binding but as we can see the result for bind is:
int res = ActivityManagerNative.getDefault().bindService(...);
return res != 0;
transaction is made through binder:
ServiceManager.getService("activity");
next:
public static IBinder getService(String name) {
try {
IBinder service = sCache.get(name);
if (service != null) {
return service;
} else {
return getIServiceManager().getService(name);
this is set in ActivityThread via:
public final void bindApplication(...) {
if (services != null) {
// Setup the service cache in the ServiceManager
ServiceManager.initServiceCache(services);
}
this is called in ActivityManagerService in method:
private final boolean attachApplicationLocked(IApplicationThread thread,
int pid) {
...
thread.bindApplication(... , getCommonServicesLocked(),...)
then:
private HashMap<String, IBinder> getCommonServicesLocked() {
but there is no "activity" only window package and alarm..
so we need get back to call:
return getIServiceManager().getService(name);
sServiceManager = ServiceManagerNative.asInterface(BinderInternal.getContextObject());
this makes call through:
mRemote.transact(GET_SERVICE_TRANSACTION, data, reply, 0);
which leads to :
BinderInternal.getContextObject()
and this is native method....
/**
* Return the global "context object" of the system. This is usually
* an implementation of IServiceManager, which you can use to find
* other services.
*/
public static final native IBinder getContextObject();
i don't have time now to dug in c so until i dissect rest call i suspend my answer.
but best way for check if service is running is to create bind (if bind is not created service not exist) - and query the service about its state through the bind (using stored internal flag on it state).
update 23.06.2018
i found those interesting:
/**
* Provide a binder to an already-bound service. This method is synchronous
* and will not start the target service if it is not present, so it is safe
* to call from {#link #onReceive}.
*
* For peekService() to return a non null {#link android.os.IBinder} interface
* the service must have published it before. In other words some component
* must have called {#link android.content.Context#bindService(Intent, ServiceConnection, int)} on it.
*
* #param myContext The Context that had been passed to {#link #onReceive(Context, Intent)}
* #param service Identifies the already-bound service you wish to use. See
* {#link android.content.Context#bindService(Intent, ServiceConnection, int)}
* for more information.
*/
public IBinder peekService(Context myContext, Intent service) {
IActivityManager am = ActivityManager.getService();
IBinder binder = null;
try {
service.prepareToLeaveProcess(myContext);
binder = am.peekService(service, service.resolveTypeIfNeeded(
myContext.getContentResolver()), myContext.getOpPackageName());
} catch (RemoteException e) {
}
return binder;
}
in short :)
"Provide a binder to an already-bound service. This method is synchronous and will not start the target service if it is not present."
public IBinder peekService(Intent service, String resolvedType,
String callingPackage) throws RemoteException;
*
public static IBinder peekService(IBinder remote, Intent service, String resolvedType)
throws RemoteException {
Parcel data = Parcel.obtain();
Parcel reply = Parcel.obtain();
data.writeInterfaceToken("android.app.IActivityManager");
service.writeToParcel(data, 0);
data.writeString(resolvedType);
remote.transact(android.os.IBinder.FIRST_CALL_TRANSACTION+84, data, reply, 0);
reply.readException();
IBinder binder = reply.readStrongBinder();
reply.recycle();
data.recycle();
return binder;
}
*

There can be several services with the same class name.
I've just created two apps. The package name of the first app is com.example.mock. I created a subpackage called lorem in the app and a service called Mock2Service. So its fully qualified name is com.example.mock.lorem.Mock2Service.
Then I created the second app and a service called Mock2Service. The package name of the second app is com.example.mock.lorem. The fully qualified name of the service is com.example.mock.lorem.Mock2Service, too.
Here is my logcat output.
03-27 12:02:19.985: D/TAG(32155): Mock-01: com.example.mock.lorem.Mock2Service
03-27 12:02:33.755: D/TAG(32277): Mock-02: com.example.mock.lorem.Mock2Service
A better idea is to compare ComponentName instances because equals() of ComponentName compares both package names and class names. And there can't be two apps with the same package name installed on a device.
The equals() method of ComponentName.
#Override
public boolean equals(Object obj) {
try {
if (obj != null) {
ComponentName other = (ComponentName)obj;
// Note: no null checks, because mPackage and mClass can
// never be null.
return mPackage.equals(other.mPackage)
&& mClass.equals(other.mClass);
}
} catch (ClassCastException e) {
}
return false;
}
ComponentName

Please use this code.
if (isMyServiceRunning(MainActivity.this, xyzService.class)) { // Service class name
// Service running
} else {
// Service Stop
}
public static boolean isMyServiceRunning(Activity activity, Class<?> serviceClass) {
ActivityManager manager = (ActivityManager) activity.getSystemService(Context.ACTIVITY_SERVICE);
for (ActivityManager.RunningServiceInfo service : manager.getRunningServices(Integer.MAX_VALUE)) {
if (serviceClass.getName().equals(service.service.getClassName())) {
return true;
}
}
return false;
}

If you have a multi-module application and you want to know that service is running or not from a module that is not depends on the module that contains the service, you can use this function:
fun isServiceRunning(context: Context, serviceClassName: String): Boolean {
val manager = ContextCompat.getSystemService(
context,
ActivityManager::class.java
) ?: return false
return manager.getRunningServices(Integer.MAX_VALUE).any { serviceInfo ->
serviceInfo.service.shortClassName.contains(vpnServiceClassName)
}
}
Usage for MyService service:
isServiceRunning(context, "MyService")
This function may not work correctly if the service class name changes and the calling function does not change accordingly.

This applies more towards Intent Service debugging since they spawn a thread, but may work for regular services as well. I found this thread thanks to Binging
In my case, I played around with the debugger and found the thread view. It kind of looks like the bullet point icon in MS Word. Anyways, you don't have to be in debugger mode to use it. Click on the process and click on that button. Any Intent Services will show up while they are running, at least on the emulator.

If the service belongs to another process or APK use the solution based on the ActivityManager.
If you have access to its source, just use the solution based on a static field. But instead using a boolean I would suggest using a Date object. While the service is running, just update its value to 'now' and when it finishes set it to null. From the activity you can check if its null or the date is too old which will mean that it is not running.
You can also send broadcast notification from your service indicating that is running along further info like progress.

My kotlin conversion of the ActivityManager::getRunningServices based answers. Put this function in an activity-
private fun isMyServiceRunning(serviceClass: Class<out Service>) =
(getSystemService(ACTIVITY_SERVICE) as ActivityManager)
.getRunningServices(Int.MAX_VALUE)
?.map { it.service.className }
?.contains(serviceClass.name) ?: false

Since Android 8 (or Oreo), API getRunningServices is deprecated.
Of course your can use #SuppressWarnings("deprecation") to get rid of the warning.
Here is how to do without getRunninngServices if your service does not need to have more than one instance: use the singleton pattern.
public class MyMusicService extends Service {
private static MyMusicService instance = null;
public static boolean isMyMusicServiceRunning() {
return instance != null;
}
Then you can call the MyMusicService.isMyMusicServiceRunning from your activities or elsewhere.