CollectionSpy. A New Java Profiler With a Collections Framework Focus
How tough can it be to use Java's Collections Framework correctly? In large systems, it turns out that most teams struggle to ensure correct usage of a variety of container classes, everything from the humble ArrayList and HashMap onwards.
CollectionSpy is a new kind of profiler which ditches universality for a hard, bug-detecting focus on all containers in the heap. This allows the tool to give you Collection-specific features which generic profilers cannot.