NewObject的上呼叫无效的间接引用

本文介绍了NewObject的上呼叫无效的间接引用的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！ 问题描述

好了，我有天然code以下。 我试图返回FilePermissionInfo从一个数组，填充（）由stat返回的一些数据。 问题是，我得到以下错误，当被NewObject的第一次调用：

OK, so I have the native code below. I'm trying to return an array of FilePermissionInfo from it, populated with some data returned by stat(). The problem is that I get the following error when NewObject is called the first time:

06-15 20：25：17.621：W / dalvikvm（2287）：无效的间接引用   0x40005820在德codeIndirectRef 06-15 20：25：17.621：E / dalvikvm（2287）：   VM终止执行

06-15 20:25:17.621: W/dalvikvm(2287): Invalid indirect reference 0x40005820 in decodeIndirectRef 06-15 20:25:17.621: E/dalvikvm(2287): VM aborting

这是奇怪的，因为只有参考对象我是JC​​LASS（对于FilePermissionInfo），我把它转化为一个全球性的参考。

It's odd, because the only reference object I have is the jclass (for FilePermissionInfo) and I turn it to a global reference.

在code是：

JNIEXPORT jobjectArray JNICALL Java_com_mn_rootscape_utils_NativeMethods_getFilesPermissions( JNIEnv* env, jobject thizz, jobjectArray filePathsArray ) { jobjectArray result; int size = (*env)->GetArrayLength(env, filePathsArray); jboolean isCopy; jclass filePermInfoCls = (*env)->FindClass(env, kFilePermissionInfoPath); if(!filePermInfoCls) { LOGE("getFilesPermissions: failed to get class reference."); return NULL; } gFilePermInfoClass = (jclass)(*env)->NewGlobalRef(env, filePermInfoCls); LOGI("got gFilePermInfoClass"); jmethodID filePermInfoClsConstructor = (*env)->GetMethodID(env, gFilePermInfoClass, "<init>", kFilePermInfoConstructorSig); if(!filePermInfoClsConstructor) { LOGE("getFilesPermissions: failed to get method reference."); return NULL; } struct stat sb; LOGI("starting..."); result = (jobjectArray)(*env)->NewObjectArray(env, size, gFilePermInfoClass, NULL); for(int i = 0; i != size; ++i) { jstring string = (jstring) (*env)->GetObjectArrayElement(env, filePathsArray, i); const char *rawString = (*env)->GetStringUTFChars(env, string, &isCopy); if(stat(rawString, &sb) == -1) { LOGE("stat error for: %s", rawString); } LOGI("%ld %ld %ld %ld %ld %ld %ld %ld", sb.st_dev, sb.st_mode, sb.st_nlink, sb.st_uid, sb.st_gid, sb.st_atime, sb.st_mtime, sb.st_ctime); jobject permInfo = (*env)->NewObject(env, gFilePermInfoClass, filePermInfoClsConstructor, (long)sb.st_dev, (long)sb.st_mode, (long)sb.st_nlink, (long)sb.st_uid, (long)sb.st_gid, (long)sb.st_atime, (long)sb.st_mtime, (long)sb.st_ctime, "", "", 1, ""); LOGI("xxx1"); (*env)->SetObjectArrayElement(env, result, i, permInfo); LOGI("xxx2"); (*env)->ReleaseStringUTFChars(env, string, rawString); LOGI("xxx3"); } (*env)->DeleteLocalRef(env, filePermInfoCls); return result;

}

Java类的构造函数签名和路径是：

The Java class constructor signature and path are:

const char* kFilePermissionInfoPath = "com/mn/rootscape/utils/FilePermissionInfo"; const char* kFilePermInfoConstructorSig = "(JJJJJJJJLjava/lang/String;Ljava/lang/String;ZLjava/lang/String;)V";

请注意，如果我叫上NewObject的默认构造函数那么它工作正常。

Please note that if I call NewObject on the default constructor then it works fine.

推荐答案

好了，找到了。 正是有了的jstring 参数有问题。事实证明，你不能将空字符串（甚至NULL为此事）作为的jstring 。 相反，我用（* ENV） - ＆GT; NewStringUTF（ENV，NULL）以创建一个空的jstring 。

OK, found it. It was a problem with the jstring parameters. It turns out you cannot pass empty strings (or even NULL for that matter) as a jstring. Instead I used (*env)->NewStringUTF(env, NULL) to create a NULL jstring.

似乎现在的工作确定。

由于这个问题产生的有点高活性，我张贴下面的最终解决方案。请注意， nullString 变量被释放在其范围结束（或当您使用它做）：

Since this question generated somewhat a high activity, I'm posting the final solution below. Note that the nullString variable is being deallocated at the end of its scope (or when you're done using it):

jstring nullString = (*env)->NewStringUTF(env, NULL); ... jobject permInfo = (*env)->NewObject(env, gFilePermInfoClass, filePermInfoClsConstructor, (jbyte)permsOwner, (jbyte)permsGroup, (jbyte)permsOthers, (jlong)sb.st_uid, (jlong)sb.st_gid, (jlong)sb.st_atime, (jlong)sb.st_mtime, (jlong)sb.st_ctime, nullString, nullString, (jboolean)1, nullString); ... (*env)->DeleteLocalRef(env, nullString);