JNI int,String array parameter, return value

int array를 parameter로 넘겨기 예제(java->jni)

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java file

public class Test {
    static {
        System.loadLibrary("test");
    }

    public static void func1(int arr[]) {
        native_func1(core);
    }

 private native static void native_func1(int arr[]);

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cpp file

static void native_func1(JNIEnv* env, jobject obj, jintArray arr) {
    int size = env->GetArrayLength(arr);

    jint *value = env->GetIntArrayElements(arr, NULL);

    for (int i = 0; i < size; i++) {
        value[i] = i;
    }
 
    env->ReleaseIntArrayElements(arr, value, 0);
    return;
}

static const JNINativeMethod g_methods[] = { 

    { "native_func1", "([I)V", (void*)native_func1 }, 

}; 

  

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//배열 생성 

int[] arr = new int[4];

//배열 전달

Test.func1(arr);

String array를 return value로 받기(jni->java)

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java file

static jobjectArray native_func2(JNIEnv* env, jobject obj) {

    char *temp[4] = { "apple, "banana", tomato", "melon"};

    jobjectArray ret = (jobjectArray)env->NewObjectArray(4, env->FindClass("java/lang/String"),

            env->NewStringUTF(""));

    for (int i = 0; i < 4; i++) {

        env->SetObjectArrayElement(ret, i, env->NewStringUTF(temp[i]));

    }

    return ret;

}

static const JNINativeMethod g_methods[] = {

    { "native_func2", "()[Ljava/lang/String;", (jobjectArray*)native_func2 },

};

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java file

public class Test {
    static {
        System.loadLibrary("test");
    }

    public static String[] func2() {

        return native_func2();

    }

    private native static String[] native_func2();

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String[] str = new String[4];

str = Test.func2();