Different result from lesson when click the Button

import java.util.Random;

public class FunFactsActivity extends Activity {

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

        //Declare our view variables and assign the views from the layout file
        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) {
                //The button was clicked,so update the fact label with a new fact
              String fact = "";
                //Randomly select a fact
                Random randomGenerator = new Random(); //Construct a new random generator
                int randomNumber = randomGenerator.nextInt();
                fact = randomNumber + "";

                //Update the label with our dynamic fact
                factLabel.setText(fact);
            }
        };
        showFactButton.setOnClickListener(listener);
    }

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

        //noinspection SimplifiableIfStatement
        if (id == R.id.action_settings) {
            return true;
        }

        return super.onOptionsItemSelected(item);
    }
}