Android provides three primary notification types for engaging users: standard, expandable, and heads-up notifications.

Standard Notifications

Standard notifications appear in the system notification drawer. Use the NotificationCompat.Builder class to construct them.

private void displayStandardNotification() {
    // Define the action when the notification is tapped
    Intent notificationIntent = new Intent(this, DetailActivity.class);
    notificationIntent.putExtra("NOTIFICATION_ID", 101);
    PendingIntent pendingIntent = PendingIntent.getActivity(this, 0, notificationIntent, PendingIntent.FLAG_IMMUTABLE);

    // Build the notification
    NotificationCompat.Builder notificationBuilder = new NotificationCompat.Builder(this, "channel_id")
            .setSmallIcon(R.drawable.notification_icon)
            .setContentTitle("App Alert")
            .setContentText("New message received.")
            .setPriority(NotificationCompat.PRIORITY_DEFAULT)
            .setContentIntent(pendingIntent)
            .setAutoCancel(true); // Dismiss on tap

    // Issue the notification
    NotificationManagerCompat notificationManager = NotificationManagerCompat.from(this);
    notificationManager.notify(101, notificationBuilder.build());
}

To programmatically dismiss a specific notification, call cancel() with its unique ID.

NotificationManager notificationManager = (NotificationManager) getSystemService(Context.NOTIFICATION_SERVICE);
notificationManager.cancel(101);

Expandable Notifications

Expandbale notifications reveal more content when the user pulls down on them. Use setStyle() with a BigTextStyle or BigPictureStyle.

private void displayExpandableNotification() {
    NotificationCompat.Builder builder = new NotificationCompat.Builder(this, "channel_id")
            .setSmallIcon(R.drawable.alert_icon)
            .setContentTitle("Weather Update")
            .setContentText("Today's forecast...")
            .setPriority(NotificationCompat.PRIORITY_DEFAULT)
            .setStyle(new NotificationCompat.BigTextStyle()
                    .bigText("Detailed forecast: Sunny skies with a high of 75°F. Winds will be light from the northwest."));

    NotificationManagerCompat.from(this).notify(102, builder.build());
}

Heads-Up Notifications

Heads-up notifications appear as a floating banner at the top of the screen for high-priority alerts. Set a high priority and optionally a vibration pattern.

private void displayHeadsUpNotification() {
    Intent fullScreenIntent = new Intent(this, UrgentActivity.class);
    PendingIntent fullScreenPendingIntent = PendingIntent.getActivity(this, 0, fullScreenIntent, PendingIntent.FLAG_IMMUTABLE);

    NotificationCompat.Builder builder = new NotificationCompat.Builder(this, "urgent_channel")
            .setSmallIcon(R.drawable.warning_icon)
            .setContentTitle("Incoming Call")
            .setContentText("John Doe is calling...")
            .setPriority(NotificationCompat.PRIORITY_HIGH) // Required for heads-up
            .setCategory(NotificationCompat.CATEGORY_CALL)
            .setFullScreenIntent(fullScreenPendingIntent, true); // Triggers heads-up display

    NotificationManagerCompat.from(this).notify(103, builder.build());
}

Notification Visibility on Lock Screen

Android allows control over notification visibility on secured lock screens using the setVisibility() method.

// Show notification on all lock screens
builder.setVisibility(NotificationCompat.VISIBILITY_PUBLIC);

// Hide sensitive content on secure lock screens
builder.setVisibility(NotificationCompat.VISIBILITY_PRIVATE);

// Hide notification entirely on secure lock screens
builder.setVisibility(NotificationCompat.VISIBILITY_SECRET);