PointersAndArrays.md

Using Pointers and Arrays

Primitive array arguments (including structs) are represented by their corresponding Java types. For example:

// Original C declarations
void fill_buffer(int *buf, int len);
void fill_buffer(int buf[], int len); // same thing with array syntax

// Equivalent JNA mapping
void fill_buffer(int[] buf, int len);

NOTE: If the parameter is to be used by the native function outside the scope of the function call, you must use Memory or an NIO direct Buffer. The memory provided by a Java primitive array will only be valid for use by the native code for the duration of the function call.

Arrays of C strings (the char* argv[] to the C main, for example), may be represented by String[] in Java code. JNA will automatically pass an equivalent array with a NULL final element.