android kotlin - Notification channel example

MainActivity.kt

package com.cfsuman.kotlintutorials

import android.app.Activity
import android.app.NotificationChannel
import android.app.NotificationManager
import android.os.Build
import android.os.Bundle
import android.widget.Button
import androidx.core.app.NotificationCompat
import androidx.core.app.NotificationManagerCompat
import java.util.*


class MainActivity : Activity() {
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main)

        // get the widgets reference from XML layout
        val button = findViewById<Button>(R.id.button)


        // Create the notification channel before showing a notification
        createNotificationChannel()

        // button click listener
        button.setOnClickListener{
            val builder = NotificationCompat
                .Builder(this, "MY_CHANNEL_ID")
                .setSmallIcon(R.drawable.ic_action_help)
                .setContentTitle("Title: API LEVEL " + Build.VERSION.SDK_INT)
                .setContentText("Description : " + UUID.randomUUID())
                .setPriority(NotificationCompat.PRIORITY_DEFAULT)

            with(NotificationManagerCompat.from(this)) {
                notify(1, builder.build())
            }
        }
    }



    // function to create notification channel
    private fun createNotificationChannel() {
        // 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 ="My Channel"
            val descriptionText = "Channel Description"
            val importance = NotificationManager.IMPORTANCE_DEFAULT
            val channel = NotificationChannel(
                "MY_CHANNEL_ID",
                name,
                importance
            ).apply {
                description = descriptionText
            }


            // Register the channel with the system
            val notificationManager: NotificationManager =
                getSystemService(NOTIFICATION_SERVICE) as NotificationManager

            notificationManager.createNotificationChannel(channel)
        }
    }
}

activity_main.xml

<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:background="#DCDCDC"
    android:id="@+id/rootLayout"
    android:padding="24dp">

    <Button
        android:id="@+id/button"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Show Notification"
        android:textAllCaps="false"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent" />

</androidx.constraintlayout.widget.ConstraintLayout>

AndroidManifest.xml [Permission]

<uses-permission android:name="android.permission.POST_NOTIFICATIONS" />