Shaking Things Up - Activity Cycle, problem with initializing variable

package com.example.crystall.ball;

import android.app.Activity;
import android.graphics.drawable.AnimationDrawable;
import android.hardware.Sensor;
import android.hardware.SensorManager;
import android.media.MediaPlayer;
import android.media.MediaPlayer.OnCompletionListener;
import android.os.Bundle;
import android.view.Menu;
import android.view.animation.AlphaAnimation;
import android.widget.ImageView;
import android.widget.TextView;
import android.widget.Toast;

import com.example.crystall.ball.ShakeDetector.OnShakeListener;
public class MainActivity extends Activity {

    private CrystalBall mCrystalBall = new CrystalBall();
    private TextView mAnswerLabel;
    private ImageView mCrystalBallImage;
    private SensorManager mSensorManager;
    private Sensor mAccelerometer;
    private ShakeDetector mShakeDetector;
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        //Declare our View variables and Assign them the Views from the layout file 
     mAnswerLabel = (TextView) findViewById(R.id.textView1);
     mCrystalBallImage = (ImageView) findViewById (R.id.imageView1); 

    mSensorManager = (SensorManager) getSystemService(SENSOR_SERVICE);
    mAccelerometer = mSensorManager.getDefaultSensor(Sensor.TYPE_ACCELEROMETER);
    mShakeDetector = new ShakeDetector(new OnShakeListener() {

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


    //Toast.makeText(this, "Yay! Our Activity Was Created!", Toast.LENGTH_LONG).show();

      Toast welcomeToast = Toast.makeText(this, "Look at me up here!", Toast.LENGTH_LONG);
      welcomeToast.setGravity(Gravity.TOP, 0, 0);
      welcomeToast.show();

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

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

    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() {
        MediaPlayer player = MediaPlayer.create(this, R.raw.crystal_ball);
        player.start();
        player.setOnCompletionListener(new OnCompletionListener() {

            public void onCompletion(MediaPlayer mp) {
                mp.release();   
                // TODO Auto-generated method stub

            }
        });
    }

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

    private void handleNewAnswer() {
        String Answer = mCrystalBall.getAnAnswer();


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

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