JDK 11+ and Javadoc

Question

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/         


        

Answer 1

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

Answer 2

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>

Answer 3

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>

Answer 4

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.

Answer 5

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>

Answer 6

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.