Android NDK获取ArrayList错误

Question

JNIEXPORT jobject JNICALL Java_com_example_androidhellojni_FooFragmentTab_getUserList(JNIEnv *env, jobject obj)
{
    jint i;
    jclass cls_arraylist = (*env)->FindClass(env, "java/util/ArrayList");
    jmethodID init_arraylist = (*env)->GetMethodID(env, cls_arraylist, "<init>", "()V");
    jobject obj_arraylist = (*env)->NewObject(env, cls_arraylist, init_arraylist, "");
    if (obj_arraylist == NULL) LOGD("obj_arrlist fail");
    jmethodID arraylist_add = (*env)->GetMethodID(env, cls_arraylist, "add", "(Ljava/lang/Object;)Z");
    if (arraylist_add == NULL) LOGD("arraylist_add fail");

    jclass cls_int = (*env)->FindClass(env, "java/lang/Integer");
    jmethodID init_int = (*env)->GetMethodID(env, cls_int, "<init>", "(I)V");

    for (i = 0; i < 10; i++) {
        jobject obj_int = (*env)->NewObject(env, cls_int, init_int, i);
        (*env)->CallObjectMethod(env, obj_arraylist, arraylist_add, obj_int);
    }

    return obj_arraylist;
}

这是我从 C 获取 return ArrayList 到 Java(Android) 的示例代码，但编译后运行存在一些错误消息，如：

art/runtime/check_jni.cc:65]     JNI DETECTED ERROR IN APPLICATION: the return type of CallObjectMethod does not match boolean java.util.ArrayList.add(java.lang.Object)
art/runtime/check_jni.cc:65]     in call to CallObjectMethod
art/runtime/check_jni.cc:65]     from java.util.ArrayList com.example.androidhellojni.FooFragmentTab.getUserList()

Answer 1

错误消息非常清楚地说明了问题所在：

the return type of CallObjectMethod does not match boolean java.util.ArrayList.add(java.lang.Object)

Call<type>Method中的type是指方法的类型，而不是方法参数的类型。方法的类型是 boolean，不是 Object.

因此您应该使用 CallBooleanMethod 来调用 arraylist_add。

Android NDK获取ArrayList错误

Android NDK get ArrayList error

android

arraylist

android-ndk