Requires

Code within modules can only use classes defined in packages that are part of its module or are in exported packages of modules it "requires."

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

module human {
    // Code within this "human" module
    // will have access to classes in
    // the "earth," "sea," and "sky" packages.
    requires reality;
}

Modules can both require other modules and export packages for other modules to use.

module human {
    requires reality;

    exports sadness;
}

These requires are not allowed form "cycles." This means that cat cannot require dog if dog also requires cat, indirectly or otherwise.

module dog {
    requires cat;
}

// Apologies to any hit Nickelodeon shows
// but this is unacceptable.
module cat {
    requires dog;
}