Notification Channels in Android O

Before Android O, users could silence an app's notifications entirely or not at all. There was no way to mute promotional alerts while keeping order updates loud, for example. Notification Channels fix that by letting developers group notifications into categories that users can configure independently.

Once a channel is created, users can adjust its importance, sound, vibration, lock screen visibility, and Do Not Disturb behaviour directly from system settings — without affecting any other channel from the same app.

## Creating a Channel

A NotificationChannel takes three arguments: a unique channel ID, a user-visible name, and an importance level. Create it through NotificationManager:

NotificationChannel channel_1 = new NotificationChannel(
    "sports",
    "Sports",
    NotificationManager.IMPORTANCE_DEFAULT
);
channel_1.setLockscreenVisibility(Notification.VISIBILITY_PUBLIC);

NotificationManager manager = (NotificationManager) getSystemService(Context.NOTIFICATION_SERVICE);
manager.createNotificationChannel(channel_1);

The channel ID ("sports" here) must be unique within the app — it's what ties a notification to its channel. You can create multiple channels for different notification types:

NotificationChannel channel_2 = new NotificationChannel(
    "finance",
    "Finance",
    NotificationManager.IMPORTANCE_HIGH
);
manager.createNotificationChannel(channel_2);

## Assigning a Notification to a Channel

Pass the channel ID to Notification.Builder:

Notification.Builder builder = new Notification.Builder(getApplicationContext(), "sports")
    .setContentTitle("Sports")
    .setContentText("India V/s New Zealand match postponed due to rain")
    .setSmallIcon(R.drawable.ic_launcher_background)
    .setChannelId("sports")
    .setAutoCancel(true);

## What Users Can Configure Per Channel

Once a channel exists, users can modify the following from Settings → App → Notifications:

• Importance — controls how interruptive the notification is (sound, heads-up, etc.)
• Sound — the notification tone for this category
• Vibration — on or off
• Blink light — LED colour and pattern
• Lock screen — show all content, hide sensitive content, or don't show
• Do Not Disturb — whether this channel can override DND

The full sample is on GitHub.