noti_sample.kt

val NOTIFICATION_ID = 1001;
createNotificationChannel(this, NotificationManagerCompat.IMPORTANCE_HIGH, false,
    getString(R.string.app_name), "App notification channel")   // 1

val channelId = "$packageName-${getString(R.string.app_name)}"
val title = "Android Developer"
val content = "Notifications in Android P"

val intent = Intent(baseContext, NewActivity::class.java)
intent.flags = Intent.FLAG_ACTIVITY_NEW_TASK or Intent.FLAG_ACTIVITY_CLEAR_TASK
val fullScreenPendingIntent = PendingIntent.getActivity(baseContext, 0,
        intent, PendingIntent.FLAG_UPDATE_CURRENT)    // 2

val builder = NotificationCompat.Builder(this, channelId)
builder.setSmallIcon(R.drawable.ic_codechacha)
builder.setContentTitle(title)
builder.setContentText(content)
builder.priority = NotificationCompat.PRIORITY_HIGH   // 3
builder.setAutoCancel(true)
builder.setFullScreenIntent(fullScreenPendingIntent, true)   // 4

val notificationManager = NotificationManagerCompat.from(this)
notificationManager.notify(NOTIFICATION_ID, builder.build())