jni native function overload signature

Question

I am trying to use function overload when declaring JNI native functions.

The Java method is :

public native static void methodaaa(String type, int errorCode);
public native static void methodaaa(String type, byte[] byts);

Without overload, the code is shown as below:

JNIEXPORT void JNICALL Java_com_xxx_yyy_JavaCallCpp_methodaaa(JNIEnv* env, jobject thiz, jstring type, jint errorCode){}

And this works just fine.

Then I tried to add overload :

JNIEXPORT void JNICALL Java_com_xxx_yyy_JavaCallCpp_methodaaa(JNIEnv* env, jobject thiz, jstring type, jint errorCode){}

JNIEXPORT void JNICALL Java_com_xxx_yyy_JavaCallCpp_methodaaa(JNIEnv* env, jobject thiz, jstring type, jbyteArray buffer){}

And this give me the error :

conflicting types for Java_com_xxx_yyy_JavaCallCpp_methodaaa

Then I did some research and it seems like I need to add a "__" to the end of the functions that I want to overload and also append the arguments Name mangling.

So I tried:

JNIEXPORT void JNICALL Java_com_xxx_yyy_JavaCallCpp_methodaaa__Ljava_lang_String_I(JNIEnv* env, jobject thiz, jstring type, jint errorCode){}

JNIEXPORT void JNICALL Java_com_xxx_yyy_JavaCallCpp_methodaaa__Ljava_lang_String_B(JNIEnv* env, jobject thiz, jstring type, jbyteArray buffer){}

But it still not work, the error is :

No implementation found for native Lcom/xxx/yyy/JavaCallCpp;.methodaaa:(Ljava/lang/String;I)V

Is anybody know that how to write the JNICALL function name with a jstring as parameter or what I am doing wrong here?

Any advice will be appreciated, thanks :)

Update:

I found the link here :

http://docs.oracle.com/javase/7/docs/technotes/guides/jni/spec/design.html

and then tried to modify my code :

JNIEXPORT void JNICALL Java_com_xxx_yyy_JavaCallCpp_methodaaa__Ljava_lang_String_2I(JNIEnv* env, jobject thiz, jstring type, jint errorCode){}

JNIEXPORT void JNICALL Java_com_xxx_yyy_JavaCallCpp_methodaaa__Ljava_lang_String_2B(JNIEnv* env, jobject thiz, jstring type, jbyteArray buffer){}

But, still I am getting the same error :

No implementation found for native Lcom/xxx/yyy/JavaCallCpp;.methodaaa:(Ljava/lang/String;I)V

Answer 1

Don't attempt to figure out JNI method signatures yourself. Use the output of javah. It is never wrong.