Abstract: A Java native interface code generator is disclosed to facilitate mixed language programming, by making native code programmed in a native language accessible to Java application programs. A programmer generates a native interface definition for native code, preferably using a neutral Interface Definition Language (IDL) to describe native code components (functions, data structures, constants and other user-defined data types), for which native mappings are to be generated. The Java native interface code generator supports complex data types, including nested data structures and multi-dimensional arrays. The Java native interface code generator reads and parses the user-derived native interface definition and generates Java Classes, data conversion code stubs and related header files. The Java Classes consist of classes of native methods, as well as classes for complex data types, which are called from Java.