I recently have taken the support and programming of a web system written in JSF. The code is kind of messy and redundant, and yes, no documentation exists.
The system has over 40 jar libraries, and most of them are redundant due to old versions and testing. To remove one jar, I must check that it's not imported in the code, so I searched the code for the jar import path (I'm using IntelliJ IDE), made sure that it's not used, and removed it.
However, after compiling the code, a number of run-time errors occurred during testing. I figured out that I removed some jars which are used by other existing jars.
The problem, how do I make sure before removing a jar that it's not used by another jar/java class?
Despite that jars have compiled classes, the compiled classes do have the import path of required libraries. But I can't search them with IntelliJ (does not search inside jars files).
The only way that I'm doing now is to test the system every time I remove a jar and see if I can crash it! This is totally not an easy way due to the huge number of features to be tested.
I wish that there is a tool where I can submit a number of java files/jars, and it displays the dependencies between them.
I know that there was a tool coming out of the JBoss project called JBoss TattleTale, might be worth taking a look:
JDepend will analyze dependencies for you for any number of JARs, class files, etc. Relating the packages it reports to those JARs should be a trivial extra step.
why don't you use Maven for your project? that will help you a lot managing dependencies.
I also found JarAnalyzer, but it doesn't seem to be maintained anymore.
Well, it is year 2013 now, so I am not sure whether this tool was great on year 2009. Just used it and found it is useful: Class Dependency Analyzer (CDA) (V1.14) http://www.dependency-analyzer.org/ This tool has a graph UI (Swing?). After add lib jars and Java classes, it will show the dependencies in Class/Package/Container(jar) level. It can also show the dependants as well. So it is easy to find the depend on jars and depended jars.
There's also ClassDep from the Jini SDK.
http://java.sun.com/products/jini/2.0/doc/api/com/sun/jini/tool/ClassDep.html
来源：https://stackoverflow.com/questions/786708/how-to-check-dependencies-between-jar-files