Play sound on power button pressed in android

I am working on an app in which "when my app is running and user presses power button" to lock the phone, then before locking it should play a sound.

I have searched for how to do this on SO on following links but didn't get any working solution: Want to Access Power Button events in android

Disable Screen Lock(Power) Button in Android

Override Power button just like Home button

How to hook into the Power button in Android?

I don't want to work with long press on power button. I just want to play my own music when the app/activity is running & user presses power button to lock the phone.

Here is my code what I've done so far:

AndroidManifest.xml

<uses-permission android:name="android.permission.PREVENT_POWER_KEY" />

<application
    android:allowBackup="true"
    android:icon="@mipmap/ic_launcher"
    android:label="@string/app_name"
    android:supportsRtl="true"
    android:theme="@style/AppTheme">
    <activity android:name=".MainActivity">
        <intent-filter>
            <action android:name="android.intent.action.MAIN" />

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

</application>

MainActivity.java

package com.example.lockunlocksound;
import android.app.Activity;
import android.content.BroadcastReceiver;
import android.media.MediaPlayer;
import android.os.Bundle;
import android.view.KeyEvent;

public class MainActivity extends Activity {

static MediaPlayer mp;

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


@Override
public boolean onKeyDown(int keyCode, KeyEvent event) {

    if (keyCode == KeyEvent.KEYCODE_POWER) {
        // Do something here...
        mp= MediaPlayer.create(this, R.raw.click123);
        mp.start();
        return true;
    }

    return super.onKeyDown(keyCode, event);
}
}

Some posts which i've mentioned above claims to work with this, but i am not getting desired output. Where am i wrong ? My phone is just getting locked without playing sound. suggest me how should i go ahead in order to solve this ?

To achieve that you can create receiver that is triggered when user presses power button and play music when that receiver is triggered:

public class MyBroadCastReciever extends BroadcastReceiver {

    MediaPlayer mediaPlayer = null;

    @Override
    public void onReceive(Context context, Intent intent) {
        mediaPlayer = MediaPlayer.create(context, R.raw.click123);
        mediaPlayer.start();
    }
}

Instantiate a reciever and register it within onCreate of your MainActivity:

MyBroadCastReciever myBroadCastReciever = new MyBroadCastReciever();
IntentFilter screenStateFilter = new IntentFilter();
screenStateFilter.addAction(Intent.ACTION_SCREEN_OFF);
registerReceiver(myBroadCastReciever, screenStateFilter);

And don't forget to unregister it inside onDestroy of your MainActivity:

unregisterReceiver(myBroadCastReciever);