I've spent some time to migrate my project written in Groovy to Java 10. Now it's possible to compile and run it. But still it doesn't use any benefits of Java 9 modularity.
Googling about Groovy and Java 9 modules gives almost nothing.
So is it possible to migrate Groovy project to use JDK 10 with Project Jigsaw modules?
Well, after a few days of experiments I come up with the answer - yes, it is possible to use Groovy with Project Jigsaw modules.
But it needs some additional effort.
Let's say we have following file structure:
├── build
├── jigsaw
│ └── module
│ └── test
│ └── Application.groovy
├── lib
│ └── groovy.all.jar
└── module-info.java
module-info.java
module main {
requires groovy.all;
}
Application.groovy
package jigsaw.module.test
class Application {
static void main(String[] args) {
println "Hello module!"
}
}
First of all we need to compile module-info.java file with javac instead of compiling all files using groovyc because groovy treats module file as closure.
Let's do it:
javac -d build --module-path lib/ module-info.java
--module-path will include our groovy.all.jar as automatic module with name derived from JAR-file name.
Next we need to compile Application.groovy
groovyc -d build jigsaw/module/test/Application.groovy
It goes smoothly.
After compilation we have module-info.class (aka module descriptor) and Application.class.
├── build
│ ├── jigsaw
│ │ └── module
│ │ └── test
│ │ └── Application.class
│ └── module-info.class
├── jigsaw
│ └── module
│ └── test
│ └── Application.groovy
├── lib
│ └── groovy.all.jar
└── module-info.java
Now let's try to run our compiled module.
java --module-path build:lib --module main/jigsaw.module.test.Application
And this is what we get
Error occurred during initialization of boot layer
java.lang.module.FindException: Unable to derive module descriptor for lib/groovy.all.jar
Caused by: java.lang.module.InvalidModuleDescriptorException: Provider class moduleName=groovy-all not in module
And what does it mean? I don't know. After a lot of googling I found something similar.
So we need to manually remove from JAR these files:
- /META-INF/services/org.codehaus.groovy.source.Extensions
- /META-INF/services/org.codehaus.groovy.runtime.ExtensionModule
Finally our Java module is able to start
java --module-path build:lib --module main/jigsaw.module.test.Application
Hello module!
All manipulations were done using Oracle JDK 10 and Groovy 2.4.15.