JDK 11+ and Javadoc

Exit code: 1 - javadoc: error - The code being documented uses packages in the unnamed module, but the packages defined in https://docs.oracle.com/en/java/javase/11/docs/api/ are in named modules.

Has anyone been able to make javadoc work without having to change the source version to 1.8 (as suggested in other forums)? I'm using JDK v11.0.5 and the issue still present (also with JDK 12+).

Edit: This error originated from maven and thrown by the maven-javadoc-plugin. I have not been able to make it work for JDK 11+ even with the <source>8</source> configuration.

As suggested in OpenJDK issue tracker this can be worked around with defining source on Javadoc plugin:

<plugin>
    <groupId>org.apache.maven.plugins</groupId>
    <artifactId>maven-javadoc-plugin</artifactId>
    <configuration>
        <source>8</source>
    </configuration>
</plugin>

Adding <detectJavaApiLink>false</detectJavaApiLink> to the Maven javadoc pluging configuration fix the error

I needed the bit from Carlos Santos to make this really work. The complete config that incorporates his answer is:

<plugin>
  <groupId>org.apache.maven.plugins</groupId>
  <artifactId>maven-javadoc-plugin</artifactId>
  <configuration>
    <source>8</source>
    <detectJavaApiLink>false</detectJavaApiLink>
  </configuration>
</plugin>

javadoc produces links to packages you use, e.g. to classes documented in .../javase/11/docs/api. While your comments are in an unnamed module, the targets are not, and javadoc can't combine those two. It produces either a package-list or an element-list file, so you can't mix unnamed modules (packages) with named modules.

I didn't find a way to limit the links that javadoc tries to produce; so you may have to use modules for your own project. This seems ridiculous to me, just to make javadoc happy. I guess this is just one of the reasons that so many people stick to Java 8.

I was able to get my own project to work by using a new version of the compiler plugin and setting the release property to 8.

<plugin>
	<artifactId>maven-compiler-plugin</artifactId>
	<version>3.8.1</version>
</plugin>

<properties>
	<maven.compiler.release>8</maven.compiler.release>
</properties>

I was facing the same issue. I was using Java 11.0.3 and org.apache.maven.plugins:maven-javadoc-plugin:2.10.4:jar. Updating the maven-javadoc-plugin version to 3.2.0 worked perfectly for me.

We can use <detectOfflineLinks>false</detectOfflineLinks> in the configuration.