Tukukkk

Currently, I'm working on my simple android studio script, and I must use volume down while the mobile screen is locked.

Please, take a look at my script:

public class MainActivity extends AppCompatActivity {



    public MediaPlayer mediaPlayer;



    @Override

    protected void onCreate(Bundle savedInstanceState) {

        super.onCreate(savedInstanceState);

        setContentView(R.layout.activity_main);



        final BroadcastReceiver vReceiver = new BroadcastReceiver() {

            @Override

            public void onReceive(Context context, Intent intent) {

                initAudio(getApplicationContext(), "https://www.w3schools.com/html/horse.mp3");

            }

        };

        registerReceiver(vReceiver, new IntentFilter("android.media.VOLUME_CHANGED_ACTION"));

    }



    @Override

    public boolean onKeyDown(int keyCode, KeyEvent event) {

        if (keyCode == KeyEvent.KEYCODE_VOLUME_DOWN) {

            event.startTracking();

            initAudio(getApplicationContext(), "https://www.w3schools.com/html/horse.mp3");

            return true;

        }

        return super.onKeyDown(keyCode, event);

    }



    public void initAudio(final Context context, String url) {

        if (mediaPlayer == null) {

            try {

                mediaPlayer = new MediaPlayer();

                mediaPlayer.setAudioStreamType(AudioManager.STREAM_MUSIC);

                mediaPlayer = MediaPlayer.create(context, Uri.parse(url));



                mediaPlayer.setOnCompletionListener(new MediaPlayer.OnCompletionListener() {

                    @Override

                    public void onCompletion(MediaPlayer mp) {

                        killMediaPlayer();

                    }

                });



                mediaPlayer.start();

            } catch (Exception e) {

                e.printStackTrace();

                Toast.makeText(context, "Fail", Toast.LENGTH_LONG).show();

                killMediaPlayer();

            }

        }

    }



    public void pauseAudio() {

        if (!(mediaPlayer == null)) {

            mediaPlayer.pause();

        }

    }



    public void startAudio() {

        if (!(mediaPlayer == null)) {

            mediaPlayer.start();

        }

    }



    public void killMediaPlayer() {

        if (mediaPlayer != null) {

            try {

                mediaPlayer.reset();

                mediaPlayer.release();

                mediaPlayer = null;

            } catch (Exception e) {

                e.printStackTrace();

            }

        }

    }

}

What should I do to fix this issue? There are no errors, the script only works when I'm with my screen unlocked.
Can you help me with this?

Thank you very much.