import java.awt.*;
import java.awt.event.*;

public class BookPick extends java.applet.Applet implements ActionListener
{
    TextField mQuery, mAnswer;
    Button bYes, bNo;
    int myLocation;

    public void init()
    {
	mQuery = new TextField(70);
  	mQuery.setText("Do you wish a mathematical approach?");
  	bYes = new Button("Yes");
  	bNo = new Button("No");
        myLocation = 0;
  	mAnswer = new TextField(70);
        bYes.addActionListener(this);
        bNo.addActionListener(this);
  	add(mQuery);
  	add(bYes);
  	add(bNo);
  	add(mAnswer);
    }

    public void actionPerformed(ActionEvent event)
    {
        Object cause = event.getSource();
        if (myLocation == 0)
        {
            if (cause == bYes)
            {
                 myLocation = 1;
  	         mQuery.setText("A programming focus instead of theory?");
            }
            if (cause == bNo)
            {
                 myLocation = 2;
  	         mQuery.setText("Narrow focus instead of overview of CS?");
            }
        }
        else if (myLocation == 1)
        {
            if (cause == bYes)
            {
                 myLocation = 3;
  	         mAnswer.setText("I recommend 'Oh! Pascal' by D. Cooper.");
            }
            if (cause == bNo)
            {
                 myLocation = 4;
  	         mAnswer.setText("'Algorithmics' by D. Harel is a fine book.");
            }
        }
        else if (myLocation == 2)
        {
            if (cause == bYes)
            {
                 myLocation = 5;
  	         mAnswer.setText("Try 'Karel the Robot' by R. Pattis.");
            }
            if (cause == bNo)
            {
                 myLocation = 6;
  	         mAnswer.setText("Enjoy A. Biermann's 'Great Ideas in CS'");
            }
        }
    }	
}