How to Create Notifiaction in Android

package com.example.notification_app;

import androidx.appcompat.app.AppCompatActivity;
import androidx.core.app.NotificationCompat;
import androidx.core.app.NotificationManagerCompat;

import android.app.NotificationChannel;
import android.app.NotificationManager;
import android.os.Build;
import android.os.Bundle;
import android.view.View;

public class MainActivity extends AppCompatActivity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);


    }

    public void clickMe(View view) {
        if(Build.VERSION.SDK_INT>=Build.VERSION_CODES.O)
        {
            NotificationChannel notificationChannel=
                    new NotificationChannel("MyNotification","MyNotiFication", NotificationManager.IMPORTANCE_DEFAULT);
            NotificationManager notificationManager=getSystemService(NotificationManager.class);
            notificationManager.createNotificationChannel(notificationChannel);
        }

        NotificationCompat.Builder builder=new NotificationCompat.Builder(this,"MyNotification")
                .setContentTitle("This is My App")
                .setSmallIcon(R.drawable.ic_launcher_foreground)
                .setAutoCancel(true)
                .setContentText("This Message For Your Security ");
        NotificationManagerCompat managerCompat=NotificationManagerCompat.from(this);
        managerCompat.notify(999,builder.build());


    }
    }