I think you're after the load() method/property of Rhino's global object/scope

load(file1.js);

load(file2.js);

load(file3.js);



methodFromFileOne();

var bar = methodFromFileTwo();

var etc = dotDotDot();

This will load a javascript source file, similar to how include/require will in PHP. Once you load a file, you'll be able to call and function or use any object defined in the loaded file.

This is how things work when you're using the Rhino shell, which is the only context I know (your question mentioned the Java SDK, which is outside my area of experience)