How to create a notification in Android?

To create a notification in Android, follow these steps:

1. Create a notification channel (for API level 26 and above).
2. Build the notification using NotificationCompat.Builder.
3. Display the notification through the notification manager.

// Creating a notification channel (API 26+)
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O) {
    String channelId = "my_channel_id";
    CharSequence channelName = "My Channel";
    String channelDescription = "Description for My Channel";
    int importance = NotificationManager.IMPORTANCE_DEFAULT;
    NotificationChannel channel = new NotificationChannel(channelId, channelName, importance);
    channel.setDescription(channelDescription);
    // Register the channel with the system
    NotificationManager notificationManager = getSystemService(NotificationManager.class);
    notificationManager.createNotificationChannel(channel);
}

// Building the notification
NotificationCompat.Builder builder = new NotificationCompat.Builder(this, "my_channel_id") // Specify the channel ID
        .setSmallIcon(R.drawable.ic_notification) // Notification icon
        .setContentTitle("Notification Title") // Title
        .setContentText("Notification text") // Text
        .setPriority(NotificationCompat.PRIORITY_DEFAULT); // Priority

// Creating a PendingIntent for the action when clicking the notification
// For example, opening an activity
Intent intent = new Intent(this, MainActivity.class);
PendingIntent pendingIntent = PendingIntent.getActivity(this, 0, intent, PendingIntent.FLAG_UPDATE_CURRENT | PendingIntent.FLAG_IMMUTABLE); // Flag for API S+
builder.setContentIntent(pendingIntent);

// Display the notification
NotificationManagerCompat notificationManagerCompat = NotificationManagerCompat.from(this);
int notificationId = 1; // Unique ID for the notification
notificationManagerCompat.notify(notificationId, builder.build());

Main components of a notification:

• Small icon: setSmallIcon(), displayed in the status bar.
• Title: setContentTitle(), the main text of the notification.
• Text: setContentText(), additional text.
• Notification channel (API 26+): A group of notifications with shared settings.
• PendingIntent: Action performed when clicking the notification.

Additionally, you can add a large image (setStyle(new NotificationCompat.BigPictureStyle())), action buttons (addAction()), and customize sound, vibration, and other parameters.