We followed https://dzone.com/articles/a-javafx-helloworld-using-java-9s-project-jigsaw-i example to make a module and expose the package containing a main module.
How to structure the modules in IntelliJ is not entirely clear yet.
Each module must define a module-info.java. Example
module com.mycompany.helloworld {
requires javafx.base;
requires javafx.graphics;
requires javafx.controls;
exports com.mycompany.helloworld;
}
A module can be looked at as a good old java-jar. The main difference with Java 8 is that you can choose which packages to expose and use, defining a more fine-grained access control.
- module: the module definition file starts with this keyword followed by its name and definition
- requires: is used to indicate the modules it depends on; a module name has to be specified after this keyword
- transitive: is specified after the requires keyword; this means that any module that depends on the module defining requires transitive <modulename> gets an implicit dependence on the <modulename>
- exports: is used to indicate the packages within the module available publicly; a package name has to be specified after this keyword
- opens: is used to indicate the packages that are accessible only at runtime and also available for introspection via Reflection APIs; this is quite significant to libraries like Spring and Hibernate, highly rely on Reflection APIs; opens can also be used at the module level in which case the entire module is accessible at runtime
- uses: is used to indicate the service interface that this module is using; a type name, i.e., complete class/interface name, has to specified after this keyword
- provides … with ...: they are used to indicate that it provides implementations, identified after the with keyword, for the service interface identified after the provides keyword
See also http://www.baeldung.com/project-jigsaw-java-modularity