Getting current state from android service

Question

I have a service, where I manage music playing. Also I have activity sending intents with user's music. When I open activity, I want to get current status of playing.

I have specific player, what have only two events: playing started and playing ends. So if I use broadcast, I will get only next event. I save events in variable lastAction when getting it. I can create new command ACTION_SEND_CURRENT_STATE. but it looks not good.

override fun onStartCommand(intent: Intent?, flags: Int, startId: Int): Int {
    when (intent?.action) {
        null -> {
            player?.cancel()
        }
        ACTION_PLAY -> {
            player?.cancel()
            player = createPlayer(intent)
            player?.start()
        }

        ACTION_STOP -> {
            player?.cancel()
        }
    }

    return START_STICKY
} 

override fun onPlayingBegin(p0: player?) {
    lastAction = BRODCAST_PLAYING_BEGIN
    sendBroadcast(Intent(BRODCAST_PLAYING_BEGIN)
            .putExtra(EXTRA_SONG, currentSong)
    )
}

How to get current state from service correctly? as state I mean last action.

Answer 1

Use this method

public static boolean isServiceRunning(Context context, Class<?> serviceClass) {
        ActivityManager manager = (ActivityManager) context.getSystemService(Context.ACTIVITY_SERVICE);
        for (ActivityManager.RunningServiceInfo service : manager.getRunningServices(Integer.MAX_VALUE)) {
            if (serviceClass.getName().equals(service.service.getClassName())) {
                return true;
            }
        }
        return false;
    }

Hope help you.

Answer 2

As pskink mentioned you need to bind your service to your activity to be able to get information from your service. If your service is working in a remote process then you need to use AIDL to communicate with your service, but I believe that if you do so you're able to find how to do that by yourself.

In your particular case the service communication might look like this(please note that the code may be not completely correct, I wrote it right from my head):

class LocalBinder(val service: MusicService) : Binder

class MusicService : Service() {
    var lastAction: String? = null
        private set
    private val binder: IBinder = LocalBinder(this)

    override fun onBind(intent: Intent) = binder

    override fun onStartCommand(intent: Intent?, flags: Int, startId: Int): Int {
        lastAction = intent?.action
        when (intent?.action) {
            null -> {
                player?.cancel()
            }
            ACTION_PLAY -> {
                 player?.cancel()
                 player = createPlayer(intent)
                 player?.start()
            }
            ACTION_STOP -> {
                 player?.cancel()
            }
        }
        return START_STICKY
    }
}

class MusicPlayerActivity : Activity() {
    private var musicService: MusicService? = null
    private val connection = object : ServiceConnection {
        override fun onServiceConnected(className: ComponentName, service: IBinder) {
            val binder = (LocalBinder) service
            musicService = binder.service
        }

        override fun onServiceDisconnected(className: ComponentName) {
            musicService = null
        }
    }

    override fun protected onStart() {
        super.onStart()
        val intent = Intent(this, MusicService::class.java)
        bindService(intent, connection, Context.BIND_AUTO_CREATE)
    }

    override fun protected onStop() {
        super.onStop()
        if (musicService != null) {
            unbind(connection)
            musicService = null
        }
    }

    fun onClick() {
        if (musicService != null) {
            musicService.lastAction // do something
        }
    }

}

Answer 3

No need to worry about the service just use foreground service as used by all music playing applications.