Exports

Inside your module-info.java file you declare which packages are "exported" from that module.

module reality {
    exports earth;
    exports sea;
    exports sky;
}

Any packages that do not have an exports declaration are "unexported packages."

The classes in unexported packages will not be visible to other modules even if those classes are public.

// Because the "backrooms" package is not exported
// from the "reality" module, other modules cannot
// observe classes within it.
package backrooms;

public class YellowCarpet {
}

package sky;


// But classes within other packages of
// the "reality" module can see it just fine.
public class Cloud {
    private final YelloCarpet fabricOfExistence
        = new YellowCarpet();

    // ...
}