Question

Currently in my application I am using C++(core implementation) and java(services and presentation). Now in my C++ core I am getting an exception, which I am catching in JNI code and creating a throwable object of it, and throwing it to java layer. So that it can be further processed.

For catching exception on jni I am using following code,

catch (namespace::MyException& excep) {
    jclass ex = jenv->FindClass("namespace/MyException");
    jmethodID constructor;
    jthrowable object;
    jobject obj;
    if (ex)
    {
            constructor = jenv->GetMethodID(ex, "<init>", "(Ljava/lang/String;Ljava/lang/String;I;I)V");
            if(!constructor)
            {
                SWIG_JavaThrowException(jenv, SWIG_JavaRuntimeException, (char*) excep.what());
                return $null;
            }

            jstring str = jenv->NewStringUTF(excep.what());
            jstring str2 = jenv->NewStringUTF(excep.GetStackTraceAsString());
            obj = jenv->NewObject(ex, constructor, str, str2,excep.GetCat(),excep.GetCate());

            object = static_cast<jthrowable>(obj);
            jenv->DeleteLocalRef(str);
            jenv->DeleteLocalRef(str2);
            jenv->Throw(object);
    }
    return $null;
}

The C++ signature for my MyException Class is

MyException(string str1, string str2, int cat1, int cat2);

But in my Jni code I am not able to get methodId For MyException CTOR.

Can any one tell me what could have gone wrong in JNI code. What I suspect is that There is some Problem in parameterList in GetMethodId().

Answer 1

You should not have any semicolons between primitives in your signature. It should be like this:

(Ljava/lang/String;Ljava/lang/String;II)V

Notice the II, not I;I.

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Edit

You can always run javap -s <package.name.ClassName> on your built classes.