# Compile C code to call JNI and link C callbacks implementations to Java extern methods
	private fun ensure_linking_callback_methods(ccu: CCompilationUnit)
	do
		var callbacks = callbacks_used_from_java.callbacks
		if callbacks.is_empty then
			ccu.body_decl.add "static int nit_ffi_with_java_registered_natives = 1;\n"
			return
		end

		ccu.body_decl.add "static int nit_ffi_with_java_registered_natives = 0;\n"

		var jni_methods = new Array[String]
		for cb in callbacks do
			jni_methods.add_all(cb.jni_methods_declaration(self))
		end
		for cb in callbacks_used_from_java.types do
			jni_methods.add_all(cb.jni_methods_declaration(self))
		end

		var cf = new CFunction("void nit_ffi_with_java_register_natives(JNIEnv* env, jclass jclazz)")
		cf.exprs.add """
	nit_ffi_with_java_registered_natives = 1;

	jint n_methods = {{{jni_methods.length}}};
	JNINativeMethod methods[] = {
		{{{jni_methods.join(",\n\t\t")}}}
	};
	jint res = (*env)->RegisterNatives(env, jclazz, methods, n_methods);
	if (res != JNI_OK) {
		PRINT_ERROR("RegisterNatives failed\\n");
		(*env)->ExceptionDescribe(env);
		exit(1);
	}
		"""
		ccu.add_local_function cf
	end