Soundboard Problem

package com.raddieltopo.soundboard.germanemployee;


import android.app.Activity;
import android.content.Intent;
import android.media.MediaPlayer;
import android.os.Bundle;
import android.view.View.OnClickListener;
import android.view.MenuInflater;
import android.view.View;
import android.view.Menu;
import android.view.MenuItem;


public class GermanEmployee extends Activity implements OnClickListener {
   private MediaPlayer a,b,c,d,e,f,g,h,i,j,k,l; 
   
   @Override
   public void onCreate(Bundle savedInstanceState) {
       super.onCreate(savedInstanceState);
       setContentView(R.layout.main);
       // Native rate is 44.1kHz 16 bit stereo, but
       // to save space we just use MPEG-3 22kHz mono
       a = MediaPlayer.create(this, R.raw.a);
       b = MediaPlayer.create(this, R.raw.b);
       c = MediaPlayer.create(this, R.raw.c);
       d = MediaPlayer.create(this, R.raw.d);
       e = MediaPlayer.create(this, R.raw.e);
       f = MediaPlayer.create(this, R.raw.f);
       g = MediaPlayer.create(this, R.raw.g);
       h = MediaPlayer.create(this, R.raw.h);
       i = MediaPlayer.create(this, R.raw.i);
       j = MediaPlayer.create(this, R.raw.j);
       k = MediaPlayer.create(this, R.raw.k);
       l = MediaPlayer.create(this, R.raw.l);
       
       // Setup click listeners
       setContentView(R.layout.main);
       
       View button0 = this.findViewById(R.id.button0);
       button0.setOnClickListener(this);
       View button1 = this.findViewById(R.id.button1);
       button1.setOnClickListener(this);
       View button2 = this.findViewById(R.id.button2);
       button2.setOnClickListener(this);
       View button3 = this.findViewById(R.id.button3);
       button3.setOnClickListener(this);
       View button4 = this.findViewById(R.id.button4);
       button4.setOnClickListener(this);
       View button5 = this.findViewById(R.id.button5);
       button5.setOnClickListener(this);
       View button6 = this.findViewById(R.id.button6);
       button6.setOnClickListener(this);
       View button7 = this.findViewById(R.id.button7);
       button7.setOnClickListener(this);
       View button8 = this.findViewById(R.id.button8);
       button8.setOnClickListener(this);
       View button9 = this.findViewById(R.id.button9);
       button9.setOnClickListener(this);
       View button10 = this.findViewById(R.id.button10);
       button10.setOnClickListener(this);
       View button11 = this.findViewById(R.id.button11);
       button11.setOnClickListener(this);
   }
 
   @Override
   public void onClick(View v) {
       MediaPlayer mp = null;
       switch (v.getId()) {
       
       case R.id.button0:
           mp=a;
           break;
       case R.id.button1:
           mp=b;
           break;
       case R.id.button2:
           mp=c;
           break;
       case R.id.button3:
           mp=d;
           break;
       case R.id.button4:
           mp=e;
           break;
       case R.id.button5:
           mp=f;
           break;
       case R.id.button6:
           mp=g;
           break;
       case R.id.button7:
           mp=h;
           break;
       default:
           mp=null;
           break;
       case R.id.button8:
           mp=i;
           break;
       case R.id.button9:
           mp=j;
           break;
       case R.id.button10:
           mp=k;
           break;
       case R.id.button11:
           mp=l;
           break;           
       
       }
       
       mp.seekTo(0);
       mp.start();
       
   } 
   
    // Called only the first time the options menu is displayed.
    // Create the menu entries.
    // Menu adds items in the order shown.
    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        super.onCreateOptionsMenu(menu);
        
        MenuInflater inflater = getMenuInflater();
        inflater.inflate(R.layout.menu, menu);
        
        // Parameters for menu.add are:
        // group -- Not used here.
        // id -- Used only when you want to handle and identify the click yourself.
        // title
        /*
        menu.add("About...");
        menu.add("Quit");
        */
        return true;
    }
    
    // Activity callback that lets your handle the selection in the class.
    // Return true to indicate that you've got it, false to indicate
    // that it should be handled by a declared handler object for that
    // item (handler objects are discouraged for reasons of efficiency).
    @Override
    public boolean onOptionsItemSelected(MenuItem item){
        
        switch(item.getItemId()) {
        
        case R.id.about:
            startActivity(new Intent(this, activity.class));
            return true;
        
        case R.id.quit:
            finish();
            return true;
           
        }
    
        return false;
    
    }
     
}