How can I pass 2 byte[] from JNI to Java

Question

I have a java method, like this:

public static native void receiveCallback(byte[] value1, byte[] value2);

In JNI I can reach the class and I can reach the method, but my parameter list is incorrect. I am trying to call the method like this:

jmethodID testJavaMethod = (java_environment)->GetMethodID(clazz, "receiveCallback","([B[B");

I then get a NoSuchMethod exception at runtime.

I followed multiple SO questions, including this one JNI - How to callback from C++ or C to Java?, but I'm still stuck.

Any suggestions?

Thanks.

Still same exception: java.lang.NoSuchMethodError: no method with name='receiveCallback' signature='([B[B)V' in class L…../LibClass; — TooManyEduardos, Mar 09 '15 at 21:39
The way you've written it, "receiveCallback" looks like it's an abstract method. That can't work. Can you post more of your code? — user2543253, Mar 10 '15 at 11:23
The method is not abstract. I added the way the method exists in java. The purpose is to just pass these 2 const char* values from c to java. — TooManyEduardos, Mar 10 '15 at 14:45

score 1 · Answer 1 · answered Mar 10 '15 at 15:45

If you want to call back into Java, the implementation must be in Java. You need

public static void receiveCallback(byte[] value1, byte[] value2) {
    // do something with value1 and value2
}

And to get the id of a static method you need to use "GetStaticMethodID". Also to call it you will have to use "CallStaticVoidMethod()".

1 Answers1