如果 GetStringUTFChars 返回了一个副本，你应该调用 ReleaseStringUTFChars 吗?

Should you call ReleaseStringUTFChars if GetStringUTFChars returned a copy?(如果 GetStringUTFChars 返回了一个副本，你应该调用 ReleaseStringUTFChars 吗?)

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，如果 isCopy 为真，它只会调用 ReleaseStringUTFChars.

Note that it only calls ReleaseStringUTFChars if isCopy is true.

但是本书Java Native Interface: Programmer's Guide and Specification(替代链接: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:

ReleaseString-Chars 调用是GetStringChars 是否有必要将 *isCopy 设置为 JNI_TRUE 或 JNI_FALSE.ReleaseStringChars 要么释放复制或取消固定实例，具体取决于根据 GetStringChars 是否有是否返回副本.

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 Gordon 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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