Crap4j is a Java implementation of the CRAP (Change Risk Analysis and Predictions) software metric – a mildly offensive metric name to help protect you from truly offensive code.

The CRAP metric combines cyclomatic complexity and code coverage from automated tests (e.g. JUnit tests) to help you identify code that might be particularly difficult to understand, test, or maintain – the kind of code that makes developers say: “This is crap!” or, if they are stuck maintaining it, “Oh, crap!”.

The best way to learn more about CRAP and Crap4j is to check the various articles, newsgroups and blogs about them.