Dependency Finder for java can help you to find your way in unknown class files/library.

Usage:

1. Import the class files - File > Extract; wait... Note: you may need to increase the JVM's memory.
2. Store the extracted information about the imported classes - File > Save
3. Select the programming elements to examine by selecting the proper checkboxes - by default it's set to packages, you may rather want classes or packages+classes.
4. Display a dependency 'graph' - File > Dependency. The symbol --> means uses, <-- means is used by.
5. You may want to limit the elements for which to show dependencies (the box Select programming elements) or their dependencies to show (the box Show dependencies (stop for closure)). The expressions use Perl regular expressions (RegExp): you specify 1 or more RegExp enclosed by '/' and '/' and separated by a comma. Example: classes containiny MyClass and (presumabely) packages starting with com.ibm: /MyClass/,/^com.ibm/

To run it, execute a script similar to the one below from its bin directory:

set DEPENDENCYFINDER_HOME=c:DependencyFinder-1.2.0
java %DEPENDENCYFINDER_OPTS% -Xms512m -Xmx1024m -classpath "%DEPENDENCYFINDER_HOME%classes";"%DEPENDENCYFINDER_HOME%libDependencyFinder.jar";"%DEPENDENCYFINDER_HOME%liblog4j.jar";"%DEPENDENCYFINDER_HOME%libjakarta-oro.jar";"%CLASSPATH%" com.jeantessier.dependencyfinder.gui.DependencyFinder