JSP/Bean Number Guess Implementation

Chris W. Johnson
Information Technology Services
The University of Texas at Austin
September 22, 2004

This implementation of the number guess game as a Java Server Pages (JSP) page and a Java Bean, is taken from the examples supplied with the Apache Tomcat 4.0.6 distribution. It was written by Jason Hunter. No criticism of Mr. Hunter or his work is intended here. His example application offers a convenient and useful illustration of how a trivial web application like this one would tend to be implemented using these technologies. I'm grateful not to have had to sit down and write a similar example.

User Experience
Java Server Page "numguess.jsp"
Java Bean Source Code "NumberGuessBean.java"

—[ Return To: “Comparison of Number Guess Implementations” ]—

User Experience

Game In Progress, Bad Input

The bad input was the number "117", but there's no indication to the user what the input was, that it was bad, or why it was considered bad. This is understandable, because it would be a fair amount of extra work to provide that, and related, user feedback.

JSP/Bean implementation of Number Guess upon receipt of invalid input.

Game Complete

JSP/Bean implementation of Number Guess upon completion of game.

The Java Server Page "numguess.jsp"

The following material is taken from the file "numguess.jsp" as distributed with Apache Tomcat 4.0.6. The copyright statement has been relocated from the top of the file to footnote 1 of this document to prevent the code size comparison from looking unfairly lopsided.

<%@ page import = "num.NumberGuessBean" %>

<jsp:useBean id="numguess" class="num.NumberGuessBean" scope="session"/>
<jsp:setProperty name="numguess" property="*"/>

<html>
<head><title>Number Guess</title></head>
<body bgcolor="white">
<font size=4>

<% if (numguess.getSuccess()) { %>

  Congratulations!  You got it.
  And after just <%= numguess.getNumGuesses() %> tries.<p>

  <% numguess.reset(); %>

  Care to <a href="numguess.jsp">try again</a>?

<% } else if (numguess.getNumGuesses() == 0) { %>

  Welcome to the Number Guess game.<p>

  I'm thinking of a number between 1 and 100.<p>

  <form method=get>
  What's your guess? <input type=text name=guess>
  <input type=submit value="Submit">
  </form>

<% } else { %>

  Good guess, but nope.  Try <b><%= numguess.getHint() %></b>.

  You have made <%= numguess.getNumGuesses() %> guesses.<p>

  I'm thinking of a number between 1 and 100.<p>

  <form method=get>
  What's your guess? <input type=text name=guess>
  <input type=submit value="Submit">
  </form>

<% } %>

</font>
</body>
</html>

The Java Bean "NumberGuessBean.java"

The following material is taken from the file "NumberGuessBean.java" as distributed with Apache Tomcat 4.0.6. The copyright statement has been relocated from the top of the file to footnote 2 of this document to prevent the code size comparison from looking unfairly lopsided.

package num;

import java.util.*;

public class NumberGuessBean {

  int answer;
  boolean success;
  String hint;
  int numGuesses;

  public NumberGuessBean() {
    reset();
  }

  public void setGuess(String guess) {
    numGuesses++;

    int g;
    try {
      g = Integer.parseInt(guess);
    }
    catch (NumberFormatException e) {
      g = -1;
    }

    if (g == answer) {
      success = true;
    }
    else if (g == -1) {
      hint = "a number next time";
    }
    else if (g < answer) {
      hint = "higher";
    }
    else if (g > answer) {
      hint = "lower";
    }
  }

  public boolean getSuccess() {
    return success;
  }

  public String getHint() {
    return "" + hint;
  }

  public int getNumGuesses() {
    return numGuesses;
  }

  public void reset() {
    answer = Math.abs(new Random().nextInt() % 100) + 1;
    success = false;
    numGuesses = 0;
  }
}

1. Copyright statement from file "numguess.jsp" of the Apache Tomcat 4.0.6 distribution:

<!--
  Copyright (c) 1999 The Apache Software Foundation.  All rights 
  reserved.

  Number Guess Game
  Written by Jason Hunter, CTO, K&A Software
  http://www.servlets.com
-->

2. Copyright statement from file "NumberGuessBean.java" of the Apache Tomcat 4.0.6 distribution: