Example notification

    private void showNotification(String uri, String title, String body) {
        NotificationHelper notificationHelper = new NotificationHelper(getBaseContext());
        NotificationCompat.Builder builder = notificationHelper.getNotification(uri,title, body);
        Random random = new Random();
        int n = random.nextInt(10000);
        notificationHelper.getManager().notify(n, builder.build());
    }

// Class
package com.pedrodev.check_version.utils;

import android.app.DownloadManager;
import android.app.Notification;
import android.app.NotificationChannel;
import android.app.NotificationManager;
import android.content.Context;
import android.content.ContextWrapper;
import android.content.Intent;
import android.graphics.Color;
import android.net.Uri;
import android.os.Build;
import android.provider.DocumentsContract;

import androidx.annotation.RequiresApi;
import androidx.core.app.NotificationCompat;
import com.pedrodev.check_version.R;
public class NotificationHelper extends ContextWrapper {

    private static final String CHANNEL_ID = "com.pedrodev.Checkversion";
    private static final String CHANNEL_NAME = "SYSnotes";

    private NotificationManager manager;

    public NotificationHelper(Context context) {
        super(context);
        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O) {
            createChannels();
        }
    }

    @RequiresApi(api = Build.VERSION_CODES.O)
    private void createChannels() {
        NotificationChannel notificationChannel = new NotificationChannel(
                CHANNEL_ID,
                CHANNEL_NAME,
                NotificationManager.IMPORTANCE_HIGH
        );
        notificationChannel.enableLights(true);
        notificationChannel.enableVibration(true);
        notificationChannel.setLightColor(Color.GRAY);
        notificationChannel.setLockscreenVisibility(Notification.VISIBILITY_PRIVATE);
        getManager().createNotificationChannel(notificationChannel);
    }

    public NotificationManager getManager() {
        if (manager == null) {
            manager = (NotificationManager) getSystemService(Context.NOTIFICATION_SERVICE);
        }
        return manager;
    }



    public NotificationCompat.Builder getNotification(String uri, String title, String body) {


        return new NotificationCompat.Builder(getApplicationContext(), CHANNEL_ID)
                .setContentTitle(title)
                .setContentText(body)
                .setColor(Color.GRAY)
                .setSmallIcon(R.mipmap.ic_launcher)
                .setAutoCancel(true)
                .setStyle(new NotificationCompat.BigTextStyle().bigText(body).setBigContentTitle(title));

    }
}