App crash upon opening

package com.sweet.sweeter;


import android.*;
import android.app.*;
import android.graphics.drawable.*;
import android.hardware.*;
import android.media.*;
import android.os.*;
import android.util.*;
import android.view.*;
import android.view.animation.*;
import android.widget.*;
import com.sweet.sweeter.ShakeDetector.*;


public class MainActivity extends Activity
{


    public static final String TAG = MainActivity.class.getSimpleName ();
    private Advisor mAdvisor = new Advisor ();
    private TextView mAnswerLabel;
    private ImageView mCrystalBallImage;
    private MediaPlayer mPlayer;
    private SensorManager mSensorManager;
    private Sensor mAccelerometer;
    private ShakeDetector mShakeDetector;


    @Override
    public void onCreate (Bundle savedInstanceState)
    {
        super.onCreate (savedInstanceState);
        setContentView (R.layout.main);

        // assigning the Views from the layout file
        mAnswerLabel = (TextView) findViewById (R.id.answer_textView);

        mCrystalBallImage = (ImageView)findViewById (R.id.imageView);
        //Setting up the SensorManager
        mSensorManager = (SensorManager) getSystemService (SENSOR_SERVICE);
        mAccelerometer = mSensorManager.getDefaultSensor (Sensor.TYPE_ACCELEROMETER);
        mShakeDetector = new ShakeDetector (new OnShakeListener (){


                public void onShake ()
                {
                    handleNewAnswer ();
                }
            });

        /*Toast.makeText(this,toastMessage, Toast.LENGTH_LONG).show();

         Toast welcomeToast = Toast.makeText(this,"Look at me way up here!", 
         Toast.LENGTH_LONG);
         welcomeToast.setGravity(Gravity.TOP,0,0);
         welcomeToast.show();*/
        Log.d (TAG, "onCreate()");
    }

    @Override
    public void onResume ()
    {   super.onResume ();
        mSensorManager.registerListener (mShakeDetector, mAccelerometer, 
                                         SensorManager.SENSOR_DELAY_UI);
    }

    @Override
    public void onPause ()
    {   super.onPause ();
        mSensorManager.unregisterListener (mShakeDetector);
        mPlayer.release ();
    }


    private void handleNewAnswer ()
    {

        String answer = mAdvisor.getAnAnswer ();

        //Update the label with our dynamic answer
        mAnswerLabel.setText (answer);

        animateCrystalBall ();
        animateAnswer ();
        playSound ();
    }

    private void animateCrystalBall ()
    {

        mCrystalBallImage.setImageResource (R.drawable.ball_animation);
        AnimationDrawable ballAnimation = (AnimationDrawable) mCrystalBallImage.getDrawable ();
        if (ballAnimation.isRunning ())
        {
            ballAnimation.stop ();
        }
        ballAnimation.start ();

    }
    private void animateAnswer ()
    {
        AlphaAnimation fadeInAnimation = new AlphaAnimation (0, 1);
        fadeInAnimation.setDuration (1500);
        fadeInAnimation.setFillAfter (true);

        mAnswerLabel.setAnimation (fadeInAnimation);
    }
    private void playSound ()
    {
        mPlayer.create (this, R.raw.crystal_ball_sound);
        mPlayer.start ();
    }


    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        getMenuInflater().inflate(R.menu.menu, menu);
        return true;
    }
}