Which module should I require in Java 9 to use JPA?

Question

I'm testing Java 9 with a project which requires JPA (javax.persistence.* classes). When I add the module-info.java and declare my module, all classes under javax.persistece package become unavailable.

I searched a lot, but I couldn't find the module to require to use JPA in a Java 9 module project.

UPDATE As Alan suggested, I ran

$ jar --describe-module --file=javax.persistence-api-2.2.jar

No module descriptor found. Derived automatic module.

[email protected] automatic
requires java.base mandated
contains javax.persistence
contains javax.persistence.criteria
contains javax.persistence.metamodel
contains javax.persistence.spi

But still with this module-info.java

module my.module {

    requires java.persistence;

}

I get "module-info.java:[3,18] module not found: java.persistence".

UPDATE 2 This is my project structure:

.
├── pom.xml
└── src
    ├── main
    │   ├── java
    │   │   ├── my
    │   │   │   └── module
    │   │   │       └── MyBean.java
    │   │   └── module-info.java
    │   └── resources
    └── test
        ├── java
        └── resources

The pom.xml has the javax.persistence-api dependency.

Testing repo: https://github.com/heruan/java9-jpa

Answer 1

With maven, you can use a dependency like

<dependency>
    <groupId>javax.persistence</groupId>
    <artifactId>javax.persistence-api</artifactId>
    <version>2.2</version>
</dependency>

with maven-compiler-plugin as updated to work with jdk9 detailed here.

Similar with dependency with gradle

compile group: 'javax.persistence', name: 'javax.persistence-api', version: '2.2'

which is based out of the javaee/jpa-spec. This would facilitate the

requires java.persistence 

as an automatic module as proposed to be the name intended for the module here.

---

Adding to the details, this is defined in the META-INF/MANIFEST.MF as :

Manifest-Version: 1.0
Bundle-Description: Java(TM) Persistence 2.2 API jar
Automatic-Module-Name: java.persistence
...

Note- The way to figure out the module name as suggested by Alan is precise, but no advertising and I still prefer using a class of some package and then let IntelliJ(2017.2.4) do that resolution for me when I say 'import class' and then 'add requires'. ;)

Answer 2

I don't think that JPA has been published as a module yet but you should be able to use it as an automatic module. Can you use jar --file=<jarfile> --describe-module to see what module name is derived for the JPA JAR file.