How do I convert jstring to wchar_t *

Question

Let\'s say that on the C++ side my function takes a variable of type jstring named myString. I can convert it to an ANSI string as follows:

Answer 1

I know this was asked a year ago, but I don't like the other answers so I'm going to answer anyway. Here's how we do it in our source:

wchar_t * JavaToWSZ(JNIEnv* env, jstring string)
{
    if (string == NULL)
        return NULL;
    int len = env->GetStringLength(string);
    const jchar* raw = env->GetStringChars(string, NULL);
    if (raw == NULL)
        return NULL;

    wchar_t* wsz = new wchar_t[len+1];
    memcpy(wsz, raw, len*2);
    wsz[len] = 0;

    env->ReleaseStringChars(string, raw);

    return wsz;
}

EDIT: This solution works well on platforms where wchar_t is 2 bytes, some platforms have a 4 byte wchar_t in which case this solution will not work.

Answer 2

If we are not interested in cross platform-ability, in windows you can use the MultiByteToWideChar function, or the helpful macros A2W (ref. example).

Answer 3

JNI has a GetStringChars() function as well. The return type is const jchar*, jchar is 16-bit on win32 so in a way that would be compatible with wchar_t. Not sure if it's real UTF-16 or something else...

Answer 4

Just use env->GetStringChars(myString, 0); Java pass Unicode by it's nature