的Android NDK获得ArrayList的错误

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; 
} 

这是我的示例代码从C得到回报的ArrayList到Java（Android版），但编译和运行存在一些错误信息，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

该错误消息很明确的问题是什么：

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

type在Call<type>Method中引用方法的类型，而不是方法参数的类型。该方法的类型是boolean，它不是Object。

因此，您应该使用CallBooleanMethod致电arraylist_add。