cannot be resolved to a variable

package com.example.crystalball;

import java.util.Random;

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.Button;
import android.widget.TextView;

public class MainActivity extends ActionBarActivity {

    @Override
    protected 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
    final TextView answerLable = (TextView) findViewById(R.id.textView1);
    Button getAnswerButton = (Button) findViewById(R.id.button1);

    getAnswerButton.setOnClickListener(new View.OnClickListener() {

        private CrystalBall mCrystalBall = new CrystalBall();

        @Override
        public void onClick(View v) {

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


    @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;
    }

    @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();
        if (id == R.id.action_settings) {
            return true;
        }
        return super.onOptionsItemSelected(item);
    }

}

String answer = mCrystalBall.getAnAnswer();
mAnswerLabel.setText(answer);

package com.example.crystalball;

import java.util.Random;

public class CrystalBall {

    public String getAnAnswer() {
        String[] answers = {
                "It is certain",
                "It is decidedly so",
                "All signs say YES",
                "The stars are not aligned",
                "My reply is no",
                "It is doubtful",
                "Better not tell you now",
                "Concentrate and ask again",
                "Unable to answer now" };

        // The button was clicked, so update the answer label with an answer
        String answer = "";

        Random randomGenerator = new Random();
        int randomNumber = randomGenerator.nextInt(answers.length);

        answer = answers[randomNumber];

        return answer;

    }
}