Passing array of strings from .c file to java dll via JNI

Question

I trying to get C# to instanciate a class in my java program. I have had a number of simpler examples working but I've hit the problem that my java class takes a string array as the constructor.

My question is how in a.c file do you create an string array that can then be passed through to the java class?

At the minute I've managed to pass across a single jString object.

Heres the method in my.c file.

jobject newClassInstance()
{

    jmethodID MID_init;
    jobject obj;
    jstring name;
    jobjectArray ret;

    MID_init = (*env)->GetMethodID (env, jClass, "<init>", "([Ljava/lang/String;)V");
    if (!MID_init) {
        printf("Error: dllClass.<init>() not found\n");
        return NULL;
    }

    name = (*env)->NewStringUTF(env,"Moo");




    obj = (*env)->NewObject(env, jClass, MID_init, name);
    if (!obj) {
        printf("Error: failed to allocate an object\n");
        return NULL;
    }
    return obj;
}

Please let me know if you need anymore information.

Kind Regards

Ash

Answer 1

• First create the array of strings.
• Create every Element String.
• Call Java Initializer with Array object.

Sample Code:

jobjectArray stringArray;
jString tmp;
char *stringA = "Test1";
char *stringB = "Test2";
jclass clsString; 
jint size = 2;

clsString = (*env)->FindClass(env, "java/lang/String");
stringArray = (*env)->NewObjectArray(env, size, clsString, 0);

tmp = (*env)->NewStringUTF(env, stringB);
(*env)->SetObjectArrayElement(env, stringArray, 0, tmp);

tmp = (*env)->NewStringUTF(env, stringA);
(*env)->SetObjectArrayElement(env, stringArray, 1, tmp);

obj = (*env)->NewObject(env, jClass, MID_init, stringArray);