I've been trying to write a Java 9 module, but no matter what I do, I get the error "package is empty or does not exist". I've tried searching online for the expected directory layout, and tried every variation on directory layout I can think of, but nothing works.
For example, here is one layout I tried
bar.foo/module-info.java
module bar.foo {
exports bar.foo;
}
bar.foo/bar/foo/wtf.java
package bar.foo;
public class wtf {
}
However, compilation still gives the same error as usual.
> javac bar.foo/module-info.java
bar.foo/module-info.java:2: error: package is empty or does not exist: bar.foo
exports bar.foo;
^
1 error
The command instead that should work is :
javac bar.foo/module-info.java bar.foo/bar/foo/wtf.java
The reason being, you're trying to compile a class which requires a package to exist i.e. bar.foo in your case. But since you haven't created one, the compiler throws the mentioned error.
It's not about the directory layout but the .class evaluated by the compiler. Providing your other class(bar.foo/bar/foo/wtf.java) creates the wtf.class within that package and hence the compiler would succeedingly compile the module-info.class as well.