Reduce external jar file size

Question

I've developed a module for a Java project. The module depends on external library (fastutil). The problem is, the fastutil.jar file is a couple of times heavier than the whole project itself (14 MB). I only use a tiny subset of the classes from the library. The module is now finished, and no-one is likely to extend it in future. Is there a way I could extract only the relevant class to some fastutil_small.jar so that others don't have to download all this extra weight?

Answer 1

Obfuscation tools such as ProGuard usually provide a feature to remove unused classes (and even fields and methods) from the jar file. You have to be careful to verify everything still works, 'though, because you might be using reflecton to access classes or methods that ProGuard can't analyze.

You can use only that feature and already get quite some saving

Or you could combine it with other space-saving obfuscation techniques (such as class and method renaming) to save even more space at the cost of harder debugging (your stack traces will become harder to parse).