Analyzing Exception Flow in Java Programs

Exception handling mechanisms provided by programming languages are intended to ease the difficulty of developing robust software systems. Using these mechanisms, a software developer can describe the exceptional conditions a module might raise, and the response of the module to exceptional conditions that may occur as it is executing. Creating a robust system from such a localized view requires a developer to reason about the flow of exceptions across modules. The use of unchecked exceptions, and in object-oriented languages, subsumption, makes it difficult for a software developer to perform this reasoning manually. In this paper, we describe a tool called Jex that analyzes the flow of exceptions in Java code to produce views of the exception structure. We demonstrate how Jex can help a developer identify program points where exceptions are caught accidentally, where there is an opportunity to add finer-grained recovery code, and where error-handling policies are not being followed.