FindBugs

FindBugs is an open-source static code analyzer created by Bill Pugh and David Hovemeyer which detects possible bugs in Java programs. Potential errors are classified in four ranks: (i) scariest, (ii) scary, (iii) troubling and (iv) of concern. This is a hint to the developer about their possible impact or severity. FindBugs operates on Java bytecode, rather than source code. The software is distributed as a stand-alone GUI application. There are also plug-ins available for Eclipse, NetBeans, IntelliJ IDEA, Gradle, Hudson, Maven, Bamboo and Jenkins.

Additional rule sets can be plugged in FindBugs to increase the set of checks performed.