Programming Assignment Checklist: Plucking a Guitar String

Pair programming. On this assignment, you are encouraged (not required) to work with a partner provided you practice pair programming. Pair programming "is a practice in which two programmers work side-by-side at one computer, continuously collaborating on the same design, algorithm, code, or test." One partner is driving (designing and typing the code) while the other is navigating (reviewing the work, identifying bugs, and asking questions). The two partners switch roles every 30-40 minutes, and on demand, brainstorm.

Before pair programming, you must read the article All I really need to know about pair programming I learned in kindergarten. You may choose a partner (of similar ability) from the same or a different precept. You and your partner will each turn in a separate individually written readme.txt for the assignment, stating who your partner is and detailing your experience. However, only one of you should turn in the assignment code.

Please note that writing code with a partner without following the pair programming instructions listed above is a serious violation of the course collaboration policy.

Frequently Asked Questions

What are the goals of this assignment? To learn how to create user-defined data types in Java and to learn about digital audio.

Where do I enter keystrokes in GuitarHeroLite and GuitarHero? Be sure that the standard draw window has focus by clicking in it. Then, type the keystrokes.

How do I determine how many elements are in an array? If you're asking this, you probably need to review Section 1.4.

What is System.out.printf()? It's for formatted printing. You could also use StdOut.printf() - see p. 124 in the textbook. You aren't required to use it, but it's useful here to align text output in columns and limit the number of digits of precision displayed.

Is the size of a RingBuffer equal to the number of nonzeros? No. Some of the elements in the buffer can be zero. To get an accurate count, increment the instance variable size each time you call enqueue() and decrement it each time you call dequeue().

What should RingBuffer do if the client attempts to dequeue() from an empty buffer or enqueue() into a full buffer? We recommend throwing an exception to indicate the error. As an example, see

How do I round a double to the nearest int? See the toGray() method in (Program 3.1.3).

What happens if I send a sample whose value is greater than 1 or less than -1 to StdAudio? The value is clipped - it is replaced by the value 1.0 or -1.0, respectively.

I get an ArrayOutOfBounds or NullPointerException error in RingBuffer. What could cause this? Does your constructor correctly initialize all of the instance variables (first, last, size, and buffer[])? Did you allocate memory for your array with new? Did you inadvertently redeclare int first or double[] buffer in a method or constructor, thereby shadowing the instance variable with the same name?

I get a Ring buffer underflow error in GuitarHeroLite before I type any keystrokes. Why? Did you forget to initialize the ring buffer to contain N zeros in your GuitarString constructor?

When I run GuitarHeroLite for the first time, I hear no sound. What am I doing wrong? Make sure you have tested with the main() provided for GuitarString. If that works, it is likely something wrong with pluck() since the main() provided for GuitarString does not test that method. To diagnose the problem, print out the values of sample() and check that they become nonzero after you type upper case characters 'A' and 'C'.

When I run GuitarHeroLite, I hear static (either just one click, and then silence or continual static). What am I doing wrong? It's likely that pluck() is working, but tic() is not. The best test is to run the main() provided for GuitarString.

How do I use keyboard.indexOf(key)? If keyboard is a String and key is a character, then keyboard.indexOf(key) return the integer index of the first occurrence of the character key in the string keyboard (or -1 if it does not occur).


Be sure to thoroughly test each piece of your code as you write it. We offer some suggestions below.


Your programs must be named,, and Use the following readme file template. Don't forget to hit the "Run Script" button on the submission system to test that it compiles cleanly.

Possible Progress Steps

These are purely suggestions for how you might make progress. You do not have to follow these steps.


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