Kotlin/Java interop method overloading pitfall

Given a Java library that defines overloaded methods for primitive and boxed types:

class X {
    public void m(int value) { ... }
    public void m(Integer value) { ... }
    ...
}

Kotlin cannot resolve a call to the overloaded method, because it does not distinguish between primitive and heap allocated types.

This code:

val x = X()
x.m(10)

Results in a compile-time error:

... TBD ...

A workaround we've found is to define a Java class with unambiguous static methods that forward to one of the overloaded methods. E.g.

class XDisambiguation {
    public static void mInt(X x, int i) { x.put(i); }
    public static void mInteger(X x, Integer i) { x.put(i); }
}

Then in Kotlin we can call either XDisambiguation.mInt(x, i) or XDisambiguation.mInteger(x, i) as required.

We'd usually hide the static calls with convenient extension methods on X.

npryce/kotlin-java-interop-overloading-pitfall.md