Collectives™ on Stack Overflow

Find centralized, trusted content and collaborate around the technologies you use most.

Teams

Q&A for work

Connect and share knowledge within a single location that is structured and easy to search.

I created a small project in Intellij Idea to mimic what I am seeing trying to migrate a large legacy codebase to OPENJDK16. Here is the directory structure:

$ tree 
/cygdrive/c/projects/play
 |--api
 |----api.iml
 |----src
 |------module-info.java (module com.company.feature.apimodule)
 |------com
 |--------company
 |----------feature
 |------------ApiRunnable.java
 |--home
 |----home.iml
 |----src
 |------module-info.java (module com.company.feature.homemodule)
 |------com
 |--------company
 |----------feature
 |------------Runnable1.java
 |--Modules
 |----.idea (Idea stuff in here)
 |----out
 |------production
 |--------api
 |--------home
module com.company.feature.apimodule
    exports com.company.feature;
package com.company.feature;
public interface ApiRunnable
    public void play(String[] strings);
module com.company.feature.homemodule
    requires com.company.feature.apimodule;       //Error Module not found
//    requires apimodule;                         //Error Module not found
//    requires com.company.feature.ApiRunnable;   //Error Module not found
package com.company.feature;
public class Runnable1 implements ApiRunnable
    @Override
    public void play(String[] strings)
        int count = 1;
        for (String str : strings)
            System.out.println("String " + count++ + " " + str);
    public static void main(String[] args)
        Runnable1 myRun = new Runnable1();
        myRun.play(args);
Note the directory structure is identical in api and home.  This is intentional as my legacy codebase has this structure.  This small example seems to duplicate the problems I am having and I can't figure out if the structure is the problem.  It did compile and run fine using the unnamed-module.
Error #1 when doing a rebuild
C:\Projects\play\home\src\com\company\feature\Runnable1.java
java: package exists in another module: com.company.feature.apimodule
Does this mean that I can't have identical package trees in api and home?
Error #2
The homemodule cannot see the apimodule, I keep getting (Module not found) no matter what I put in the requires line.
Is this related to Error #1?  If not, how do I fix this without resorting to the unnamed module for everything?
This problem was resolved by putting the module-info.java in the right directory.  This is poorly documented and was found by trial and error.
The right directory is api:
module apimodule
    exports com.company.feature;
and home:
module homemodule
    requires apimodule;
It appears that once the module-info.java files are in place, the Runnable1.java doesn't need the import statements, since the imported package is the same as the local one.
        
Thanks for contributing an answer to Stack Overflow!
Please be sure to answer the question. Provide details and share your research!
But avoid …
Asking for help, clarification, or responding to other answers.
Making statements based on opinion; back them up with references or personal experience.
To learn more, see our tips on writing great answers.