CODEWITHSUNDEEP
java-native-interface
Avinash
Avinash

Reputation: 51

Create ArrayList<String> Object in JNI

I have a callback method in Java which is called by a native thread. One of the parameter of callback is an ArrayList object.

I am not able to get classref for ArrayList and its methods. Tried with "Ljava/util/ArrayList" but in vain. Please suggest a solution. thanks in advance

Upvotes: 5

Views: 3848

Answers (2)

ademar111190
ademar111190

Reputation: 14505

I don't understood right, but i think you need anything like it:

void methodToCallJava(std::vector<YourClassCpp*> itens) {
    JNIEnv* env;
    YourSavedJVM->AttachCurrentThread(&env, NULL);
    jclass clazzDelegate = env->FindClass("your/delegate/class");
    jclass clazzYourClassJava = env->FindClass("your/class/java");
    jmethodID methodIdDelegate = env->GetMethodID(clazzDelegate, "delegateMethod", "(Ljava/util/ArrayList;)V");
    jobjectArray arrayListFromCpp = nullptr;
    jsize arrayListFromCppLength = itens.size();
    if (arrayListFromCppLength > 0)
        arrayListFromCpp = env->NewObjectArray(arrayListFromCppLength, clazzYourClassJava, methodToCreateJavaObjectFromCppObject(env, itens.at(0)));
    for (jsize c = 1; c < arrayListFromCppLength; c = c + 1)
        env->SetObjectArrayElement(arrayListFromCpp, c, methodToCreateJavaObjectFromCppObject(env, itens.at(c)));
    env->CallVoidMethod(this->delegate, methodIdDelegate, arrayListFromCpp);
}

Upvotes: 1

maba
maba

Reputation: 48075

The class reference would be:

jclass cls = (*env)->FindClass(env, "java/util/ArrayList");

OR

jclass cls = (*env)->FindClass(env, "Ljava/util/ArrayList;");

You have an extra L in front of the java/util/ArrayList. In that case you also need to append a ;.

Upvotes: 1

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