Lab 4 - CS 202 - Computer Science II

CS 202 - Computer Science II - Fall 2005 Lab 4

Loyola College > Department of Computer Science > Dr. James Glenn > CS 202 > Labs > Lab 4

Due

Monday, October 31st at 11:59pm. Projects submitted after the due date will be assessed a 20% penalty per day. Projects will not be accepted more than four days late.

Objectives

to read text files

Introduction

In 1979, Atari introduced the high score table with its Asteroids arcade game ¹. The high score table showed the initials of the players with the ten highest scores since the machine had been turned on. This appeal to people's vanity encouraged players to spend more quarters in an effort to achieve some small measure of fame.

Assignment

Complete the given code in the HighScores class so it displays a high score table that is read from a file. Your code will have to create JLabels to hold the data read and add those labels to the appropriate panels.

You will have to

Open the file for input.
Write a loop that reads until it reaches the end-of-file. The loop should:
- create a label to hold the name just read and add that label to namesPanel,
- read the line containing the date and score,
- create and use a tokenizer to break apart that line,
- create labels for the date and score and add them to rightPanel (note that dates are given in seconds since January 1, 1970, and that they are longs), and
- read the next line (the next name) from the file.
Finally, your code should close the file.

You will also need to add the appropriate import statements, and use try and catch to handle any exceptions that are thrown by the code you wrote.

Files

You should start with the given code for HighScores.java.

Here is a sample high scores file.

Advice

You can start by writing code that displays the names only to make sure you are opening the file correctly and that your try and catch blocks are correct. This may be easier if you assume that the file will always contain 10 high scores.

Once that works, you can add code that uses a StringTokenizer to handle the date and score.

Finally, modify your loop so it reads until the end of the file instead of always reading 10 entries. Check your modification editing the file so it contains more than 10 entries and edit it again so it contains fewer than 10 entries.

Extra Credit

In main, use a JFileChooser to allow the user to select what file to open. The Java 1.4.2 documentation has good sample code for using JFileChoosers.

Exercises

To be done individually.

If the data for one entry (name, date, and score) were stored in the file on a single line, how would you break that line apart? That is, how could you tell where the name ends and the date and score begin (taking into account short names like Madonna and long names like Juan Antonio de la Cruz)?
Explain what would have to be changed in the current code if you did not want to handle exceptions in the HighScores constructor.
If we were to develop a class to model a high score table, what data fields would it contain (that is, what would be required to store in memory all of the data that is being displayed by the application)?

Submissions

Submit the source code (.java files) for HighScores.

¹ The History of Video Games, http://www.gamespot.com/gamespot/features/video/hov/index.html, visited Oct. 28, 2004.