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I’m trying to implement remote binding between two different Android apps. The first app contains a ClientActivity that binds to a Service in the second app. The service is supposed to generate a random number and send it back to the activity using Messenger. However, the communication between the two apps is not working as expected.

APP 1(Client App)

class ClientActivity : AppCompatActivity() {

private var binding : ActivityMainBinding? = null
private var senderMessenger: Messenger? = null
private var receiverMessenger: Messenger? = null
val RECEIVED_CONST_VALUE = 0
private var isBind = false
private var serviceIntent : Intent? = null
private var serviceConnection: ServiceConnection? = null

inner class MyHolder(val view: TextView) : Handler() {
    override fun handleMessage(msg: Message) {
        if (msg.what == RECEIVED_CONST_VALUE) {
            Log.d("x", "this is calling")
            val randomValue = msg.arg1
            view.text = "Random no is : $randomValue"
        }
        super.handleMessage(msg)
    }
}

override fun onCreate(savedInstanceState: Bundle?) {
    super.onCreate(savedInstanceState)
    binding = ActivityMainBinding.inflate(layoutInflater)

    serviceIntent = Intent("ars.example.conceptprectice.MyService")
    serviceIntent!!.setPackage("ars.example.conceptprectice")
    setContentView(binding?.root)

    serviceConnection = object : ServiceConnection {
        override fun onServiceConnected(name: ComponentName?, serviceBinder: IBinder?) {
            Log.d("B", "Service Connected Called")
            senderMessenger = Messenger(serviceBinder)
            receiverMessenger = Messenger(MyHolder(binding?.text!!))
            isBind = true
        }

        override fun onServiceDisconnected(name: ComponentName?) {
            Log.d("A", "Service Disconnected Called")
            senderMessenger = null
            receiverMessenger = null
            isBind = false
        }
    }

    binding?.bind?.setOnClickListener {
        bindService(serviceIntent!!, serviceConnection!!, BIND_AUTO_CREATE)
        Toast.makeText(this, "Service bound!", Toast.LENGTH_SHORT).show()
    }

    binding?.unbind?.setOnClickListener {
        Toast.makeText(this, "Service unbound!", Toast.LENGTH_SHORT).show()
        unbindService(serviceConnection!!)
        isBind = false
    }

    binding?.generate?.setOnClickListener {
        if (isBind) {
            val message = Message.obtain(null, 0)
            message.replyTo = receiverMessenger
            try {
                senderMessenger?.send(message)
            } catch (e: RemoteException) {
                Toast.makeText(this, "Something went wrong", Toast.LENGTH_SHORT).show()
            }
        } else {
            Toast.makeText(this, "Service is not bound!", Toast.LENGTH_SHORT).show()
        }
    }
}

override fun onDestroy() {
    serviceConnection = null
    super.onDestroy()
}

}

APP 2(Service)

class MyService : Service() {
private var isRandomStart = false
private var GET_COUNT = 0

inner class RandomNumberRequestHandler : Handler() {
    override fun handleMessage(msg: Message) {
        if (msg.what == GET_COUNT) {
            val messageSendRandNo = Message.obtain(null, 0)
            messageSendRandNo.arg1 = generateRandom()

            try {
                msg.replyTo.send(messageSendRandNo)
            } catch (e: RemoteException) {
                Log.d("RE", e.message.toString())
            }
        }
        super.handleMessage(msg)
    }
}

private val randomMessageMessenger = Messenger(RandomNumberRequestHandler())

override fun onStartCommand(intent: Intent?, flags: Int, startId: Int): Int {
    isRandomStart = true
    Thread {
        while (isRandomStart) {
            Thread.sleep(1000)
            Log.d("IM", "Thread ID: ${Thread.currentThread().id} :: ${generateRandom()}")
 }
 }.start()
    return START_STICKY
}

override fun onDestroy() {
    stopRandomGen()
    Log.d("IMX", "Service Destroyed")
    super.onDestroy()
}

override fun onBind(intent: Intent?): IBinder? {
    Log.d("IMX", "Service Bound")
    return randomMessageMessenger.binder
}

override fun onUnbind(intent: Intent?): Boolean {
    Log.d("IMX", "Service Unbound")
    return super.onUnbind(intent)
}

fun generateRandom(): Int = (0..100).random()

fun stopRandomGen() { isRandomStart = false }
}

Issue:

The service binds successfully, but the random number is not getting displayed in the TextView.
It seems like the message from the remote service is not reaching the client activity.

Things I’ve tried:

Ensured that both apps are signed with the same key and have the same android:sharedUserId.
Verified that the MyService is declared properly in the AndroidManifest.xml of the service app.

AndroidManifest.xml (Service App):

<service
android:name=".MyService"
android:exported="true"
android:permission="android.permission.BIND_REMOTE_SERVICE">
<intent-filter>
    <action android:name="ars.example.conceptprectice.MyService"/>
</intent-filter>
</service>

`