NotificationChannelCreate.java

if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O) {
    NotificationManager notificationManager = (NotificationManager) getSystemService(Context.NOTIFICATION_SERVICE);
    NotificationChannel notificationChannel = new NotificationChannel("channel_id", "channel_name", NotificationManager.IMPORTANCE_DEFAULT);
    notificationChannel.setDescription("channel description");
    notificationChannel.enableLights(true);
    notificationChannel.setLightColor(Color.GREEN);
    notificationChannel.enableVibration(true);
    notificationChannel.setVibrationPattern(new long[]{100, 200, 100, 200});
    notificationChannel.setLockscreenVisibility(Notification.VISIBILITY_PRIVATE);
    notificationManager.createNotificationChannel(notificationChannel);
}

NotificationChannelGroup.java

  if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O) {
      NotificationManager notificationManager = (NotificationManager) getSystemService(Context.NOTIFICATION_SERVICE);

      NotificationChannelGroup group1 = new NotificationChannelGroup("channel_group_id", "channel_group_name");
      notificationManager.createNotificationChannelGroup(group1);

      NotificationChannel notificationChannel = new NotificationChannel("channel_id", "channel_name", NotificationManager.IMPORTANCE_DEFAULT);
      notificationChannel.setDescription("channel description");
      notificationChannel.setGroup("channel_group_id");
      notificationChannel.enableLights(true);
      notificationChannel.setLightColor(Color.GREEN);
      notificationChannel.enableVibration(true);
      notificationChannel.setVibrationPattern(new long[]{100, 200, 100, 200});
      notificationChannel.setLockscreenVisibility(Notification.VISIBILITY_PRIVATE);
      notificationManager.createNotificationChannel(notificationChannel);
}