如果GetStringUTFChars返回副本，你应该调用ReleaseStringUTFChars吗？ [英] Should you call ReleaseStringUTFChars if GetStringUTFChars returned a copy?

问题描述

Rob Gordon的Essential JNI：Java Native Interface一书包含以下代码示例，用于将jstring转换为C字符串：

The book "Essential JNI: Java Native Interface" by Rob Gordon contains the following code example to convert a jstring to a C string:

const char* utf_string;
jboolean isCopy;
utf_string = env->GetStringUTFChars(str, &isCopy);
/* ... use string ... */
if (isCopy == JNI_TRUE) {
    env->ReleaseStringUTFChars(str, utf_string);
}

请注意，它只调用 ReleaseStringUTFChars 如果 isCopy 为真。

Note that it only calls ReleaseStringUTFChars if isCopy is true.

但书 Java Native Interface：程序员指南和规范（备用链接： http://192.9.162.55/docs/books/jni/html/objtypes.html#5161 ）说：

But the book Java Native Interface: Programmer's Guide and Specification (alternate link: http://192.9.162.55/docs/books/jni/html/objtypes.html#5161) says:

无论GetStringChars是否将
设置为* isCopy，ReleaseString-Chars调用都是
必需的JNI_TRUE或JNI_FALSE。
ReleaseStringChars释放
副本或取消实例，取决于
，取决于GetStringChars是否有
返回副本。

The ReleaseString-Chars call is necessary whether GetStringChars has set *isCopy to JNI_TRUE or JNI_FALSE. ReleaseStringChars either frees the copy or unpins the instance, depending upon whether GetStringChars has returned a copy or not.

我认为这是戈登书中的错误是正确的吗？

I am correct in assuming this is a bug in Gordon's book?

推荐答案

是的，你的假设是正确的（你应该总是调用ReleaseStringUTFChars）。

Yes, your assumption is correct (you should always call ReleaseStringUTFChars).

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