Unnamed Modules cannot be read

Question

I got really nasty problem that I do not understand...

We have a whole set of util-libraries written with jdk8 and no relation to jigsaw so we also do not have set the Automatic-Module-Name within the META-INF file.
Now we need to migrate a product to java11 that uses these util-libraries.
I created a module-info.java and entered all required modules but there are some problems with the util-libraries.
Some of the util libraries are loaded as unnamed-modules and it is possible to add them as required modules. But for some other of these util-libraries it is not possible to add them because they do not get a module-name based on their jar-file.

From my IDE I get the folloging error:

package 'x' is declared in the unnamed module but module 'y' does not read it.

package x is within one of our util-libraries and module y is the product that should be migrated to java11.

Any ideas so that I can understand this problem?

Best regards

How does your jar-filenames look like? If there are numbers in it at different positions that could be a problem. — Ralf Renz
– Ralf Renz, Commented Aug 12, 2019 at 8:39
the jarfiles are from my local maven repository and the naming is simply up to normal conventions: "autent-saml-redirect-binding-client-0.2.1.jar" — Goldfish
– Goldfish, Commented Aug 12, 2019 at 9:05

zaphod · Accepted Answer · 2019-09-10 11:00:26Z

I use AdoptOpenJDK jdk-11.0.3.7-hotspot and had the following exception message at runtime

class A (in module A) cannot access class B (in unnamed module @0x12345678) because module A does not read unnamed module @0x12345678

and solved it by using the --add-reads vm argument

--add-reads iamdsim.heat.adapter=ALL-UNNAMED

I read somewhere that only automatic modules "read" the unnamed module by default. But i could not find it in the java.lang.module packagedoc.

Edit: It is documented in The State of the Module System

jar-files with names for which no automatic module name can be derived are always a pain. It happens with numbers or reserved words like "interface" in the name (e.g. "db-interface-1.0.0.jar").

Goldfish · Accepted Answer · 2019-09-11 05:11:33Z

The solution of this specific problem was just my IDE. IntelliJ does not support reading "unnamed modules" or "automatic modules" from imported "projects" within the IDE. I already started a bugreport at jetbrains.

Hi, do you have the case number for this issue so that we can trace it as well?

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