PMD is a Java source code analyzer. The PMD JEdit Plugin requires at least JEdit 4.0final. Here's the PMD web site.
First, you may have to delete old version of the PMD plugin from your jars directory... you can pretty much just delete any jar file starting with "pmd" to be on the safe side. Then, unzip the PMD-Jedit .zip file. Just unzip it into your JEdit directory and it'll put a couple of jar files into your jars directory, restart JEdit, and you'll be ready to go.
The software adds a new menu item group into the Plugins menu of the editor view. There are several menu items:
The JEdit Plug-in is free software, released under the Apache license.