Do class comments aid Java program understanding?

This paper describes an experiment that investigates the effects of class and method comments on Java program understanding among beginning programmers. Each of the 103 students from CS1 class at Oregon Slate University was given one of four versions (no comments, only method comments, only class comments, and both method and class comments) of a Java database program and answered questions about the program. The results indicated that method comments do increase low-level program understanding, while class comments did not increase high-level understanding. This raises questions about the role of class comments in object-oriented programs, as well as the kind of commenting guidelines that should be used in teaching CS1 classes.