Android Kotlin: listening to the event when the device receives a new text message is not working

Question

I am building an Android application using Android. In my app, I am trying to do something when the device receives a new text message even if the app is closed. Basically, I am trying to show notification when a new text message is received. I am using broadcaster for that. But it is not working as expected.

This is my receiver.

class SmsListener:  BroadcastReceiver() {
    private lateinit var notificationManager: NotificationManager
    private lateinit var notificationChannel: NotificationChannel
    lateinit var builder: Notification.Builder
    private val channelId = "i.apps.notifications"
    private val description = "Test notification"
    private lateinit var context: Context

    override fun onReceive(context: Context?, intent: Intent?) {
        this.context = context as Context
        if(intent?.getAction().equals("android.provider.Telephony.SMS_RECEIVED")) {
            val bundle = intent!!.extras //---get the SMS message passed in---

            var msgs: Array<SmsMessage?>? = null
            var msg_from: String
            if (bundle != null) {
                //---retrieve the SMS message received---
                try {
                    val pdus =
                        bundle["pdus"] as Array<Any>?
                    msgs = arrayOfNulls<SmsMessage>(pdus!!.size)
                    for (i in msgs.indices) {
                        msgs[i] = SmsMessage.createFromPdu(pdus!![i] as ByteArray)
                        msg_from = msgs[i]!!.getOriginatingAddress() as String
                        val msgBody: String = msgs[i]!!.getMessageBody()
                        //@TODO: display the notification. When clicked, redirect the user to the message details activity with a share button

                        if (! msgBody.isNullOrEmpty()) {
                            showNotification(msgBody)
                        }
                    }
                } catch (e: Exception) {

                }
            }
        }
    }

    private fun showNotification(message: String) {
        //@TODO: remove the identifier from the message
        //@TODO: confirm number of characters for message description
        initialiseNotificationManager()
        val intent = Intent(this.context, MessageDetailsActivity::class.java)
        intent.putExtra(MessageDetailsActivity.KEY_MESSAGE, message)
        val pendingIntent = PendingIntent.getActivity(this.context, 0, intent, PendingIntent.FLAG_UPDATE_CURRENT)
        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O) {
            initialiseNotificationChannel()
            builder = Notification.Builder(this.context, channelId).setContentTitle("22222: New message received.").setContentText(message.take(50)).setSmallIcon(R.drawable.common_google_signin_btn_icon_dark).setLargeIcon(BitmapFactory.decodeResource(this.context.resources, R.drawable
                    .ic_launcher_background)).setContentIntent(pendingIntent)
        }
        notificationManager.notify(12345, builder.build())
    }

    private fun initialiseNotificationChannel(){
        if (! this::notificationChannel.isInitialized) {
            if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O) {
                notificationChannel = NotificationChannel(channelId, description, NotificationManager .IMPORTANCE_HIGH)
                notificationChannel.lightColor = Color.BLUE
                notificationChannel.enableVibration(true)
                notificationManager.createNotificationChannel(notificationChannel)
            }
        }
    }

    private fun initialiseNotificationManager() {
        if (! this::notificationManager.isInitialized) {
            notificationManager = this.context.getSystemService(Context.NOTIFICATION_SERVICE) as NotificationManager
        }
    }
}

This is how I registered the receiver in the AndroidManifest.xml file.

<receiver android:name=".SmsListener">
            <intent-filter>
                <action android:name="com.forkthecoup.com22222.SmsListener" ></action>
                <action android:name="android.provider.Telephony.SMS_RECEIVED" />
            </intent-filter>
        </receiver>

This is how I register the receiver in the main activity

try {
            // register the broadcast receiver to catch the incoming messages
            var filter = IntentFilter()
            filter.addAction("com.forkthecoup.com22222.SmsListener")
            val receiver: SmsListener = SmsListener()
            registerReceiver(receiver, filter)
            sendBroadcast(Intent("com.forkthecoup.com22222.SmsListener"))
        } catch (e: Exception) {

        }

Yes, I have granted the right permissions to the app to receive and send the messages. But when the app receives a new message, it is not showing the notification. What is wrong with my code and how can I fix it?

Answer 1

You haven't added the notification for Api 24 and below here is the code

   private fun showNotification(message: String) {
        //@TODO: remove the identifier from the message
        //@TODO: confirm number of characters for message description
        initialiseNotificationManager()
        val intent = Intent(this.context, MainActivity::class.java)
        intent.putExtra("MainActivity.KEY_MESSAGE", message)
        val pendingIntent = PendingIntent.getActivity(this.context, 0, intent, PendingIntent.FLAG_UPDATE_CURRENT)
        builder = if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O) {
            initialiseNotificationChannel()
            Notification.Builder(this.context, channelId).setContentTitle("22222: New message received.").setContentText(message.take(50)).setSmallIcon(R.drawable.common_google_signin_btn_icon_dark).setLargeIcon(BitmapFactory.decodeResource(this.context.resources, R.drawable
                    .ic_launcher_background)).setContentIntent(pendingIntent)
        } else {
            Notification.Builder(this.context).setContentTitle("22222: New message received.").setContentText(message.take(50)).setSmallIcon(R.drawable.common_google_signin_btn_icon_dark).setLargeIcon(BitmapFactory.decodeResource(this.context.resources, R.drawable
                    .ic_launcher_background)).setContentIntent(pendingIntent)
        }
        notificationManager.notify(12345, builder.build())
    }