mediaplayer - horizontal view click and stop play

On my first click on image, sound is not playing, on second click sound play but If I click on same button twice or more time it's keep all before clicked audio playing in the background and play again and again. Please help , I am Beginner's, Here is my code:

import android.content.Context;
import android.media.MediaPlayer;
import android.os.Bundle;
import android.support.v7.app.ActionBarActivity;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.widget.ImageView;


public class MainActivity extends ActionBarActivity {

private static MediaPlayer mp = null;

ImageView im;

/**
 * Stop old sound and start new one
 */
public static void play(Context context, int resource) {
    stop(context);

    mp = MediaPlayer.create(context, resource);
    mp.setLooping(false);
    mp.start();
}

/**
 * Stop the music
 */
public static void stop(Context context) {
    if (mp != null) {
        mp.stop();
        mp.release();
        mp = null;
    }
}

@Override
protected void onCreate(Bundle savedInstanceState) {
    // getWindow().setFormat(PixelFormat.RGBA_8888);
    // getWindow().addFlags(WindowManager.LayoutParams.FLAG_DITHER);

    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);

}

@Override
public boolean onCreateOptionsMenu(Menu menu) {
    // Inflate the menu; this adds items to the action bar if it is present.
    getMenuInflater().inflate(R.menu.menu_main, menu);
    return true;
}



@Override
public boolean onOptionsItemSelected(MenuItem item) {
    // Handle action bar item clicks here. The action bar will
    // automatically handle clicks on the Home/Up button, so long
    // as you specify a parent activity in AndroidManifest.xml.
    int id = item.getItemId();

    //noinspection SimplifiableIfStatement
    if (id == R.id.action_settings) {
        return true;
    }

    return super.onOptionsItemSelected(item);
}

public void biggerView(View v)

{

    im = (ImageView) findViewById(R.id.selected);


    switch (v.getId())

    {

        case R.id.image1:
            im.setImageResource(R.drawable.im1);

            //MediaPlayer.create(getApplicationContext(), R.raw.play1).start();

            findViewById(R.id.image1).setOnClickListener(new View.OnClickListener() {

                @Override
                public void onClick(View v) {

                    play(getApplicationContext(), R.raw.play8);
                }
            });
            break;

        case R.id.image2:

            im.setImageResource(R.drawable.im2);
            findViewById(R.id.image2).setOnClickListener(new View.OnClickListener() {

                @Override
                public void onClick(View v) {

                    play(getApplicationContext(), R.raw.play2);
                }
            });
            break;

        case R.id.image3:
            im.setImageResource(R.drawable.im3);
            findViewById(R.id.image3).setOnClickListener(new View.OnClickListener() {

                @Override
                public void onClick(View v) {

                    play(getApplicationContext(), R.raw.psicek);
                }
            });
            break;

        case R.id.image4:
            im.setImageResource(R.drawable.im4);
            //MediaPlayer.create(getApplicationContext(), R.raw.play4).start();
            break;

        case R.id.image5:
            im.setImageResource(R.drawable.im5);
            //MediaPlayer.create(getApplicationContext(), R.raw.play5).start();
            break;

        case R.id.image6:
            im.setImageResource(R.drawable.im6);
            //MediaPlayer.create(getApplicationContext(), R.raw.play6).start(); //just test with diff start
            break;

        case R.id.image7:
            im.setImageResource(R.drawable.im7);
            //mp = MediaPlayer.create(MainActivity.this, R.raw.play7); //just test with diff start
            //mp.start();
            break;

        case R.id.image8:
            im.setImageResource(R.drawable.petelin);
            //mp = MediaPlayer.create(MainActivity.this, R.raw.play8);
            //mp.start();

            play(getApplicationContext(), R.raw.petelin_rooster);
            //Toast.makeText(getApplicationContext(),"Kliknil na 8 (osmo) slikco !",Toast.LENGTH_LONG).show();

    }
 }

}