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I am converting a java project to use modules. One of my modules depends on hamcrest library, and it needs both of the jar files hamcrest.core and hamcrest.library. These two jar files both have org.hamcrest package. So when my module wants to treat these two jars as automatic modules, it fails because two modules in a module-path cannot have packages with same name. I searched a lot and found some related stuff on stackoverflow. It seems that I have two reasonable options if I do not want to rebuild those dependencies:

  1. Merge the two jars into one jar using my build automation tool (which is maven).
  2. Somehow tell java compiler that these two jars should be treated as a single automatic module.

So here are my questions:

  • Is any of these two options possible? If yes, how?
  • Is there any better option?

Thanks in advance

Feri
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    The cleanest of all solutions would be to report and get it fixed in the library itself. Some links/reports useful in such cases -https://github.com/hamcrest/JavaHamcrest/issues/187, https://github.com/hamcrest/JavaHamcrest/issues/205 – Naman Nov 11 '18 at 05:18
  • That's right for sure but I am in hurry :) – Feri Nov 11 '18 at 16:52
  • Did you try to let those jars remain on the *classpath* instead of *modulepath* to result into an unnamed module? Not sure though [that would be something you're looking for](https://stackoverflow.com/questions/51828014/how-split-packages-are-avoided-in-java-9). – Naman Nov 11 '18 at 17:07
  • Unfortunately explicit module cannot read classpath. It says if the explicit module is treatd as unnamed module "TEMPORARILY", that would work but I've no idea what this even means! – Feri Nov 11 '18 at 18:34

1 Answers1

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Ok I finally managed to solve it like this:

  1. Create a new maven module called hamcrest-all and add dependencies on hamcrest-core and hamcrest-library.
  2. add maven-assembly-plugin to this module with appendAssemblyId set to false.
  3. remove the dependency to hamcrest-core and hamcrest-library from other maven modules and instead add dependency to hamcrest-all.
  4. exclude hamcrest-core and hamcrest-library when including dependency to hamcrest-all.

What it actually does is that it unpacks hamcrest-core and hamcrest-library in the jar file created for hamrest-all. And because each jar file is treated as one module by JMPS, the problem is gone :)

Feri
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