Android java: notification pattern code

add permission in project 

AndroidManifest.xml

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

MainActivity.java 

   @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        EdgeToEdge.enable(this);
        setContentView(R.layout.activity_main);
        ViewCompat.setOnApplyWindowInsetsListener(findViewById(R.id.main), (v, insets) -> {
            Insets systemBars = insets.getInsets(WindowInsetsCompat.Type.systemBars());
            v.setPadding(systemBars.left, systemBars.top, systemBars.right, systemBars.bottom);
            return insets;
        });

        checkPermissions();
    ....
    }



    /*
     * check permission to read contact and write shared folder Download
     */
    private void checkPermissions() {
        List<String> permissions = new ArrayList<>();

        // 1. Android 13+ Notification Permission
        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.TIRAMISU) {
            permissions.add(Manifest.permission.POST_NOTIFICATIONS);
        }

        // API require string convert List<String> to String[];
        requestPermissionLauncher.launch(permissions.toArray(new String[0]));
    }

    /*
     * callback permission request
     */
    private final ActivityResultLauncher<String[]> requestPermissionLauncher =
            registerForActivityResult(new ActivityResultContracts.RequestMultiplePermissions(), result -> {
                // Handle Notification permission (Android 13+)
                boolean notificationsGranted = true;
                if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.TIRAMISU) {
                    notificationsGranted = result.getOrDefault(Manifest.permission.POST_NOTIFICATIONS, false);
                }

            }); 

create MyNotificationService.java class

public class MyNotificationService {

    public static final String CHANNEL_ID = "wredatexthelper"; //
    public static final int NOTIF_ID = 1846496091;  // crc from wredatexthelper

    /*
     * to send notification directly
     */
    public static void sendNotification(Context context, String title, String message) {
        NotificationManager notificationManager =
                (NotificationManager) context.getSystemService(Context.NOTIFICATION_SERVICE);

        NotificationCompat.Builder myNotifBuilder = getNotificationBuilder(context);
        myNotifBuilder
                .setContentTitle(title)
                .setContentText(message);

        notificationManager.notify(NOTIF_ID, myNotifBuilder.build());
    }

    /*
     * Helper that returns the BUILDER so you can customize it before building
     */
    private static NotificationCompat.Builder getNotificationBuilder(Context context) {
        NotificationManager notificationManager =
                (NotificationManager) context.getSystemService(Context.NOTIFICATION_SERVICE);

        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O) {
            if (notificationManager.getNotificationChannel(CHANNEL_ID) == null) {
                NotificationChannel notifChannel = new NotificationChannel(
                        CHANNEL_ID,
                        "Background Sync Service",
                        NotificationManager.IMPORTANCE_LOW
                );
                notificationManager.createNotificationChannel(notifChannel);
            }
        }

        return new NotificationCompat.Builder(context, CHANNEL_ID)
                .setSmallIcon(android.R.drawable.stat_notify_sync)
                .setPriority(NotificationCompat.PRIORITY_LOW)
                .setCategory(Notification.CATEGORY_SERVICE);
        //.setOngoing(true); // can not swap away
    }

    /*
     * get notification for foreground called from worker
     */
    public static Notification getForegroundNotification(Context context) {
        Notification myNotif = getNotificationBuilder(context).build();
        return myNotif;
    }
}