BackSound

 package com.me;

import android.app.Service;
import android.content.Intent;
import android.content.SharedPreferences;
import android.media.MediaPlayer;
import android.os.IBinder;
import android.preference.PreferenceManager;

import androidx.annotation.Nullable;

public class MyService extends Service {

    private MediaPlayer player;
    @Nullable
    @Override
    public IBinder onBind(Intent intent) {
        return null;
    }

    @Override
    public int onStartCommand(Intent intent, int flags, int startId) {
        SharedPreferences sharedPref = PreferenceManager.getDefaultSharedPreferences(getBaseContext());//customer.this
        Boolean on= sharedPref.getBoolean("on", true);
        if (on){
            player = MediaPlayer.create(this, R.raw.backsound);
            player.setLooping(true);
            player.start();
        }

        return START_NOT_STICKY;

    }

    @Override
    public void onDestroy() {
        super.onDestroy();
        try {
            player.stop();
            player.release();
        }
        catch (Exception ee){}
    }
}

=======================

  <activity
            android:name=".Video_Thumbnail2"
            android:screenOrientation="portrait">
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />

                <category android:name="android.intent.category.DEFAULT" />
            </intent-filter>
        </activity>


        <service android:name=".MyService"/>
    </application>

</manifest>

============================

public void login(View view){
    MediaPlayer klik = new MediaPlayer().create(this, R.raw.clik);
    klik.start();

    Intent intent = new Intent(getApplicationContext(), MainActivity.class);
    startActivity(intent);
    startService(new Intent(getApplicationContext(), MyService.class));
}

@Override
public void onBackPressed() {
    super.onBackPressed();
    moveTaskToBack(true);
    stopService(new Intent(getApplicationContext(), MyService.class));
}

hasil   = findViewById(R.id.hasil);
nilai   = findViewById(R.id.nilai);
Typeface typeface = Typeface.createFromAsset(getAssets(),"fonts/FredokaOneRegular.ttf");
hasil.setTypeface(typeface);
nilai.setTypeface(typeface);


Reff: https://android-coffee.com/tutorial-how-to-play-youtube-videos-in-android-with-videoview/