Semmle is an Eclipse plugin that allows « you to search your Java code by writing your own queries in .QL, an object-oriented query language », quite similar to SQL in fact.

In others words, you can search anything you want to know about your code by writing a simple .QL query and executing it. The results are displayed in a tree (see first screenshot).
Several charts can also be displayed.

An example of the query that can be run:

from
Class c, string name
where
name = c.getPackage().getName()
and name.matches(« abc% »)
select
c.getPackage()
c

Quite similar to SQL, isn’t it?

I must confess that I didn’t try this plugin for the moment, but I must find some time to test it…

Some screenshots of the plugin (click to enlarge pictures):


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