Kotlin: What can I do when a Java library has an overload of both primitive and boxed type?

Question

For example, FastUtil's IntArrayList has a push method that accepts both int (primitive) and Integer (boxed), but Kotlin sees these both as the same function push(Int), therefore I cannot use the function at all as the function is ambiguous.

What should I do when a Java library has overloads for both the primitive and boxed type?

(p.s. I am aware that I can use the add(int) method. I am in search of what to do if I come across such a problem in the future.)

Answer 1

Consider these methods in Java:

void f(int x) { }
void f(Integer y) { }

In Kotlin, they are seen as

f(x: Int)
f(x: Int!)

^{The second method has a parameter of platform type, meaning it might be nullable, corresponding to Integer.}

First one can be simply called with Kotlin Int passed:

f(5) // calls f(int x)

To call the second one, you can cast the argument to nullable Int?, thus selecting the overload:

f(5 as Int?) // calls f(Integer y)

Answer 2

Have you tried writing a Java class to serve as an intermediary? That is, write your own java class with the method you want Kotlin to see, then call that method from your Kotlin code.