Automatic module name containing number

Question

I want to use Java 9 in my app. One of my dependencies has a jar name:

sdk-http-ahc-2_0

Unfortunately, when I try to change it to automatic module, the name for the module is not valid.

requires sdk.http.ahc.2_0; // not valid

Am I missing something with naming the module? What are my other options here?

Answer 1

The problem is that the module system does not identify 2_0 as a version number and hence doesn't strip it when determining the automatic module name. Unfortunately, 2_0 is not a valid Java identifier and can hence not be used as a segment in a module name.

The solution is to either rename the JAR or add the Automatic-Module-Name entry to the JAR's manifest:

1. Create a file manifest.txt with the following content:

   Automatic-Module-Name: sdk.http.ahc
   

2. Then use jar to append that line to the existing manifest:

   jar --update --file sdk-http-ahc-2_0.jar --manifest=manifest.txt
   

Note that locally modifying existing JARs (name or manifest) can cause problems down the road. Consider changing the Maven version of the file to something like 2.0-patched-auto-name (or similar) and add it to your local Maven repository. If the project is shared with other developers and you have a local Nexus, you can put it in there. Otherwise send a mail to everyone with the steps to add it to their local repo. 😜