FindBugs - A Bug Pattern Detector for Java: "FindBugs - A Bug Pattern Detector for Java
This is the web page for FindBugs, a program which looks for bugs in Java code. It is free software, distributed under the terms of the Lesser GNU Public License.
FindBugs requires JRE (or JDK) 1.4.0 or later to run. However, it can analyze programs compiled for any version of Java.
The current version of FindBugs is 0.8.7, released on April 15, 2005."