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

Answer 1

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.

Answer 2

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)