Memview: a pedagogically-motivated visual debugger

Novice programmers often have difficulty understanding the interactions between the objects in their programs. Many studies have shown that visual representations of computer memory can aid students\´ comprehension. One such representation, developed by Gries and Gries, divides computer memory into three areas: one for the call stack, one for static objects allocated on the heap ("static space"), and one for normal heap objects ("object space"). Memview, an extension to the DrJava IDE developed at Rice University, is a dynamic, interactive display of computer memory based on this model. Its simple three-pane representation shows novices the life cycle of objects, and helps them understand three key concepts: the notion of an "address" in memory, how storing an address creates a reference from one object to another, and the differences between the heap, the stack, and static space. User tests conducted during the summer of 2004 demonstrated that Memview facilitated faster completion of common introductory programming problems. Since then, Memview has been used in an introductory programming course to illustrate basic data structures such as linked lists. We are presently refining the tool based on further feedback from students and instructors