CS 134 Lab Style Guide

The way you present your program is just as important as having a correct program. While having good comments or good variable names will not affect the correctness of your program, it will make it easier to read your program. It is important that others be able to understand your code so that they can modify your code if they have to. Half of your lab grade will be determined by your programming style.

This is a guide to help you better understand what we are looking for when we look at your labs. As the semester progresses there will be steeper penalties for styling mistakes. So, get into the habit of writing good labs from the beginning. After writing your lab, be sure to look over your code and your style.


Comments are extremely important. Take some care to write accurate yet concise comments.

You should write comments for:

  1. Class (Program): At the top of each class, you should write your name, date of creation, and a brief description of what the class is for. If you decide to do more than the assignment requested, you should describe these "extra" features in the program under the class description. Sometimes it's hard to tell a bug from a feature.
  2. Methods: Above each method heading there should be a brief description of what the method does. You should also describe what each parameter means and what the return result means. If the method code is simple you do not need to comment in the method body. If the method body is complicated, you might want to add some comments to certain areas that you deem to be complicated. Be careful not to overcomment!
  3. Variables and constants: In general, variables and constants should all have comments as to what the variable is used for. For example a good comment for your variable Line diagonal in NoClicking would be: // the slash in the prohibit sign. Occasionally several closely related variables or constants can be grouped together under the same comment.

Blank Lines

Blank lines are used to delineate different areas of the code. The instance variable declarations at the top of your program should be separated from the header of the class and the header of the first method. There should always be space between methods. It is advisable to break up long method bodies and long declarations into logical pieces. Always start a new line after the semicolon. Always leave a blank line before a comment line.


You should always choose names that suggest the meanings of the things being named. If the purpose of a method is to draw a rectangle, then a good name for that method is drawRect. If there is a variable of type FilledRect that is used as the stem of a stop sign, then a good name would be stem or stemRect.

By convention, constants (indicated by "static final" in Java) are all capital letters, classes begin with uppercase, variable and method names begin with lowercase, while uppercase is used to start new words in multi-word names.

Instance variables should never be declared to be public. Instance variables should only be used when a value must be saved for use after a constructor or method has been completed. Otherwise local variables should be used.


Your program should be organized as neatly as possible. You might find it helpful to select BlueJ's Auto-layout format command from the Edit menu to keep your program readable.