How should I pass and return unsigned int by value from Java to C/C++ in jna

Question

My C++ function

extern "C" {
   DECLSPEC unsigned int STDCALL doNumberThing(unsigned int some_number);
}

My Java Interface

package com.myplace.nativeapi;

import com.sun.jna.Library;
import com.sun.jna.Memory;
import com.sun.jna.Pointer;

interface NativeAPI extends Library {
    int doNumberThing(int some_number);
}

Obviously this has a problem when dealing with values that are only valid for one or the other of the mismatched types (int vs unsigned int); what is the recommended way to get around this? One answer elsewhere recommends "IntByReference", but unless I've misunderstood, they're talking about the long*, not the actual unsigned int being passed by value.

(This is trimmed down example code, if there's a syntax error, let me know in the comments and I'll update the question)

Answer 1

JNA provides the IntegerType class , which can be used to indicate an unsigned integer of some particular size. You'll have to use a Java long to hold a native unsigned int in primitive form, since its values may be outside the range of Java int , but in general you can pass around the IntegerType object and only pull the primitive value out as needed.

public class UnsignedInt extends IntegerType {
    public UnsignedInt() {
         super(4, true);
    }
}