Android Kotlin Trigger Notification

This tutorial shows how to trigger notification programatically with Kotlin for API29 and above. At the time of this post, highest is API31.

Create a basic activity project. Notification will be triggered by the floating action button.

Modify your onCreate function into this below. Import all the missing libraries.

override fun onCreate(savedInstanceState: Bundle?) {
    super.onCreate(savedInstanceState)

    binding = ActivityMainBinding.inflate(layoutInflater)
    setContentView(binding.root)

    setSupportActionBar(binding.toolbar)

    val navController = findNavController(R.id.nav_host_fragment_content_main)
    appBarConfiguration = AppBarConfiguration(navController.graph)
    setupActionBarWithNavController(navController, appBarConfiguration)

    var mContext = this
    lateinit var notificationBuilder: NotificationCompat.Builder
    val notificationManager = NotificationManagerCompat.from(mContext)
    val CHANNEL_ID = "My_Notification_Channel"

    // Create the NotificationChannel, but only on API 26+ because
    // the NotificationChannel class is new and not in the support library
    if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O) {
        val name = "Channel Name"
        val descriptionText = "Channel Description"
        val importance = NotificationManager.IMPORTANCE_DEFAULT
        val channel = NotificationChannel(CHANNEL_ID, name, importance).apply {
            description = descriptionText
        }
        // Register the channel with the system
        val notifiManager: NotificationManager =
            mContext.getSystemService(Context.NOTIFICATION_SERVICE) as NotificationManager
        notifiManager.createNotificationChannel(channel)
    }

    // Create an explicit intent for an Activity in your app
    val sampleIntent = Intent(mContext, MainActivity::class.java).apply {
        flags = Intent.FLAG_ACTIVITY_NEW_TASK or Intent.FLAG_ACTIVITY_CLEAR_TASK
    }
    val pendingIntent: PendingIntent = PendingIntent.getActivity(mContext, 0, sampleIntent, 0)

    /***
     * Notice that the NotificationCompat.Builder constructor requires that you provide a channel ID.
     * This is required for compatibility with Android 8.0 (API level 26) and higher,
     * but is ignored by older versions.
     */
    notificationBuilder = NotificationCompat.Builder(mContext, CHANNEL_ID)
        .setSmallIcon(R.drawable.notification_icon)
        .setContentTitle("Notification Title")
        .setContentText("Notification Body Text, Notification Body Text")
        .setPriority(NotificationCompat.PRIORITY_DEFAULT)
        // Set the intent that will fire when the user taps the notification
        .setContentIntent(pendingIntent)
        // Automatically removes the notification when the user taps it.
        .setAutoCancel(true)

    binding.fab.setOnClickListener { view ->
        Snackbar.make(view, "Replace with your own action", Snackbar.LENGTH_LONG)
            .setAction("Action", null).show()
        with(NotificationManagerCompat.from(mContext)) {
            // notificationId is a unique int for each notification that you must define
            notificationManager.notify(0, notificationBuilder.build())
        }
    }
}

Next add notification icon. Download the zip. It should be a res folder. Copy the res folder into the Android project res folder.

https://romannurik.github.io/AndroidAssetStudio/icons-notification.html#source.type=clipart&source.clipart=notifications&source.space.trim=1&source.space.pad=0&name=notification_icon

Run the app. Click on the floating action button. It will trigger a notification at the top quick action menu bar.

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