NotificationManagerCompat on Android Oreo

Using NotificationManagerCompat with AndroidX is the recommended way.

NotificationManagerCompat now supports Notification channels. The new version Added Notification channels methods to NotificationManagerCompat so developers can use only NotificationManagerCompat when working with notifications.

For Java, include the following in your build.gradle file

implementation 'androidx.core:core:1.2.0'

For Kotlin, include the following instead of the above dependency in your build.gradle file

implementation 'androidx.core:core-ktx:1.2.0'

To display a notificaiton, you will have to do the following

1. Create and register notification channel.
2. Create a notification.
3. Show the notification

The snippets below are in Kotlin, but you can also use Java if you want.

1. Create and register a notification channel.

Notification channels provide a common visual and auditory experience for notifications of a similar type. Since their introduction in API 26, you are now required to set a channel for a notification, otherwise they will not display on newer versions of Android.

So define a helper method as shown below to create a notification channel for you.

//define your channel id
val CHANNEL_ID = "com.yourpackagename.your_channel_id"

//create notification channel for android Oreo and above devices.
if (Build.VERSION.SDK_INT >= 26) {
    val channel = NotificationChannel(CHANNEL_ID , "Your channel name", NotificationManager.IMPORTANCE_DEFAULT)
    NotificationManagerCompat.from(this).createNotificationChannel(channel)
}

2. Create a notification.

Use the NotificationCompat.Builder to create a Notificaiton. Please note that the CHANNEL_ID is passed to the builder.

var builder = NotificationCompat.Builder(this, CHANNEL_ID)
    .setSmallIcon(R.drawable.notification_icon)
    .setContentTitle("My notification")
    .setContentText("Much longer text that cannot fit one line...")
    .setStyle(NotificationCompat.BigTextStyle()
            .bigText("Much longer text that cannot fit one line..."))
    .setPriority(NotificationCompat.PRIORITY_DEFAULT)

3. Show the notification

To make the notification appear, call NotificationManagerCompat.notify(), passing it a unique ID for the notification and the result of NotificationCompat.Builder.build()

   NotificationManagerCompat.from(this).notify(notificationId, builder.build())

That's all :)

I usually use this class to manage notification channels:

class NotificationManager(private val context: Context) {

    companion object {
        private val CHANNEL_ID = "YOUR_CHANNEL_ID"
        private val CHANNEL_NAME = "Your human readable notification channel name"
        private val CHANNEL_DESCRIPTION = "description"
    }

    @RequiresApi(Build.VERSION_CODES.O)
    fun getMainNotificationId(): String {
        return CHANNEL_ID
    }

    @RequiresApi(Build.VERSION_CODES.O)
    fun createMainNotificationChannel() {
            val id = CHANNEL_ID
            val name = CHANNEL_NAME
            val description = CHANNEL_DESCRIPTION
            val importance = android.app.NotificationManager.IMPORTANCE_LOW
            val mChannel = NotificationChannel(id, name, importance)
            mChannel.description = description
            mChannel.enableLights(true)
            mChannel.lightColor = Color.RED
            mChannel.enableVibration(true)
            val mNotificationManager = context.getSystemService(Context.NOTIFICATION_SERVICE) as android.app.NotificationManager
            mNotificationManager.createNotificationChannel(mChannel)
    }
}

Then you can use util like this

fun createNotificationCompatBuilder(context: Context): NotificationCompat.Builder {
    if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O) {
        return NotificationCompat.Builder(context, NotificationManager(context).mainNotificationId)
    } else {
        return NotificationCompat.Builder(context)
    }
}

This way you can use it in any place of your application with signature just like you have used before and you can easily change it in case of future changes.

Since NotificationManagerCompat is just a wrapper class that makes life easier, you can create the channels normally:

if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O) {
    val name = getString(R.string.channel_title)
    val description = getString(R.string.channel_description)
    val importance = NotificationManager.IMPORTANCE_HIGH
    val mChannel = NotificationChannel(CHANNEL_ID, name, importance)
    mChannel.description = description
    mChannel.enableLights(true)
    mChannel.lightColor = Color.parseColor("#5B3C88")
    mChannel.enableVibration(true)
    mChannel.vibrationPattern = longArrayOf(100, 200, 300, 400, 500, 400, 300, 200, 400)
    val manager = (context.getSystemService(Context.NOTIFICATION_SERVICE) as NotificationManager)
    manager.createNotificationChannel(mChannel)
}

And then use the NotificationManagerCompat when you post the notifications, but don't forget to construct the notification using the new constructor:

NotificationCompat.Builder(context, CHANNEL_ID)