I am stuck on the Shake detector

private Crystalball mCrystalball = new Crystalball();
private Sensor mAccelerometer;
private ShakeDetector mShakeDetector;

package com.example.crystalball;

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 com.example.crystalball.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);

        //Asign 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();


                // TODO Auto-generated method stub
            }           
    });
        }


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);//1500Ml is 1,5 seconde
        fadeInAnimation.setFillAfter(true);
        mAnswerLabel.setAnimation(fadeInAnimation);
    }

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

        @Override
        public void onCompletion(MediaPlayer mp) {
            mp.release();

        }
    });


}

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


private void handleNewAnswer() {
    mAnswerLabel.setText(answer);
        animateCrystalBall();
        animateAnswer();
        playSound();
}
}