So that phrase specifically meant you can't use CFML member functions on Java arrays, but you usually can pass a Java array to a BIF that expects a CFML array.

Maybe try this: https://trycf.com/gist/f61fa9bf51ccfad8e4e7888647629fdd/acf2021?theme=monokai

cfmlArray = ["a", "b", "c"]
javaArray = cfmlArray.toArray()

writeDump([
    cfml = [
        array = cfmlArray,
        class = cfmlArray.getClass().getName(), // coldfusion.runtime.Array <-- they are completely different types of object
        methods = arrayMap(cfmlArray.getClass().getMethods(), (method) => method.getName()) // therefore they have completely different methods
    ],
    java = [
        array = javaArray,
        class = javaArray.getClass().getName(), // java.lang.Object[] <-- they are completely different types of object
        methods = arrayMap(javaArray.getClass().getMethods(), (method) => method.getName()) // therefore they have completely different methods
    ]
])

When one says just "array" one is being imprecise. They are actually objects of two completely different types of class. So... like... obviously (?) one can only call the methods for the class the object is a type of? It's not about "you can't call member functions on a java array". It's "you can't call the member functions of a

coldfusion.runtime.Array

on an object that isn't a

coldfusion.runtime.Array

. Now... the way CFML member functions are implemented are not quite as straight fwd as that because... ugh... CFML sux, basically... but for the purposes of this discussion that's how you need to understand it.

I could implement a class

me.adamcameron.util.Array

, and it's an array, but that doesn't mean you can call methods from

coldfusion.runtime.Array

or

java.lang.Object[]

. You can only call its own methods, ie the ones defined in the

me.adamcameron.util.Array

class.