What is this "this"

[Peter Sorotokin]

Hi
There is a Android source code that I understand it amd know what it does except the role of "this" as a parameter to a method .
The code :

package org.example.audio;

import android.app.Activity;
import android.media.AudioManager;
import android.media.MediaPlayer;
import android.os.Bundle;
import android.view.View;
import android.view.View.OnClickListener;

public class Audio extends Activity implements OnClickListener {
   private MediaPlayer mp;

   @Override
   public void onCreate(Bundle savedInstanceState) {
      super.onCreate(savedInstanceState);
      setContentView(R.layout.main);
      setVolumeControlStream(AudioManager.STREAM_MUSIC);
      findViewById(R.id.button_1).setOnClickListener(this);
      findViewById(R.id.button_2).setOnClickListener(this);
      findViewById(R.id.button_3).setOnClickListener(this);
      findViewById(R.id.button_4).setOnClickListener(this);
      findViewById(R.id.button_5).setOnClickListener(this);
      findViewById(R.id.button_6).setOnClickListener(this);
      findViewById(R.id.button_7).setOnClickListener(this);
      findViewById(R.id.button_8).setOnClickListener(this);
      findViewById(R.id.button_9).setOnClickListener(this);
   }

   public void onClick(View v) {
      int resId;
      switch (v.getId()) {
      case R.id.button_1: resId = R.raw.button_1; break;
      case R.id.button_2: resId = R.raw.button_2; break;
      case R.id.button_3: resId = R.raw.button_3; break;
      case R.id.button_4: resId = R.raw.button_4; break;
      case R.id.button_5: resId = R.raw.button_5; break;
      case R.id.button_6: resId = R.raw.button_6; break;
      case R.id.button_7: resId = R.raw.button_7; break;
      case R.id.button_8: resId = R.raw.button_8; break;
      case R.id.button_9: resId = R.raw.button_9; break;
      default:            resId = R.raw.button_1; break;
      }
      // Release any resources from previous MediaPlayer
      if (mp != null) {
         mp.release(); 
      }
      // Create a new MediaPlayer to play this sound
      mp = MediaPlayer.create(this, resId); 
      mp.start();
   }
}

In lines 18 to 26 , what is the role of "this" ??? To which it refers ??? Is it the strange "context" ???
Thanks for your help

[Ulf Dittmer]

"this" in Java refers to the object in which it is used, in this case to the "Audio" class. The method probably takes an Activity or a Context as parameter.