FindBugs

FindBugs is an open source Java project for static analysis. It scans Java bytecode to identify potential bugs. This tool provides early feedback about potential errors in the code. It helps the developer to access all type of bug early in the development phase.

Features:
     1. Can identify bug patterns with complete accuracy
     2. It provides support for the Guava library, recognizing many common misuse patterns.
     3. Support detection of problems identified by JSR-305 annotations

More Information and Official Website:
Download : http://findbugs.sourceforge.net/downloads.html