I can't understand why my my button will not work with my random generator no answers.

private FactBook mFactBook = new FactBook();

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_fun_facts);

    final TextView factLabel = (TextView) findViewById(R.id.factTextView);
    Button showFactButton = (Button) findViewById(R.id.showFactButton);
    View.OnClickListener listener = new View.OnClickListener() {
        @Override
        public void onClick(View view) {

           String fact = mFactBook.getFact();

            factLabel.setText("fact");
        }
    };
    showFactButton.setOnClickListener(listener);


}


}

public String[] mFacts = {

        "Ostriches run faster than horses.",
        "Gold medals are actually made more of silver.",
        "Men run faster than women.",
        "Elephants weigh heavier than some small cars.",
        "The giant squid is real.",
        "Bids are a direct descendant of the RAPTOR.",
        "The worlds gold is running out.",
        "Woman can multi-task better than men.",
        "Ufo's are not real."
};
public String getFact(){
    String fact = " ";

    Random randomGenerator = new Random(); // construct a new random operator
    int randomNumber = randomGenerator.nextInt(mFacts.length);
    // if randomNumber equal to 0 then
    fact = mFacts[randomNumber];

    return fact;


}