IntStream何时实际关闭？ SonarQube S2095对IntStream是误报吗？ [英] When is an IntStream actually closed? Is SonarQube S2095 a false positive for IntStream?

问题描述

我使用Java 8流代替许多旧式for循环来迭代一堆结果并生成摘要统计信息。例如：

I am using Java 8 streams in place of many old style for loops to iterate through a bunch of results and produce summary statistics. For example:

int messages = IntStream.rangeClosed(0, 7).map(ids::get).reduce(Integer::sum).getAsInt();

注意：我知道还有其他方法可以进行上面显示的计数。我这样做是为了说明我的问题。

我正在使用SonarQube 5.3和Java 3.9插件。在该配置中，上面的代码行违反了squid规则S2095：资源应该关闭。这是我期望看到AutoCloseable（例如，FileInputStream）被打开但从未关闭的结果。

I am using SonarQube 5.3 with the Java 3.9 plugin. In that configuration, the above line of code gives me a violation of squid rule S2095: "Resources should be closed." That's the result I would expect to see if an AutoCloseable (e.g., a FileInputStream) was opened but never closed.

所以这是我的问题：终端操作 reduce 关闭流吗？应该是？或者这是鱿鱼规则中的误报？

So here's my question: does the terminal operation reduce close the stream? Should it? Or is this a false positive in the squid rule?

推荐答案

它没有关闭，因为 AutoCloseable 界面仅适用于 try-with-resources 。但是对于 IntStream ，这个关闭操作是完全没必要的，因为它在 AutoCloseable 接口 javadoc ：

It isn't closed, because AutoCloseable interface works only inside try-with-resources. But this close operation is totally unnecessary for IntStream as it said in AutoCloseable interface javadoc:

然而，当使用java.util.stream.Stream等设施时，
支持我/ O-based和非基于I / O的表单，try-with-resources
块在使用非基于I / O的表单时通常是不必要的。

However, when using facilities such as java.util.stream.Stream that support both I/O-based and non-I/O-based forms, try-with-resources blocks are in general unnecessary when using non-I/O-based forms.

所以是：S2095是IntStream的误报。希望通过 SONARJAVA-1478 确定这一点

So yes S2095 is a false positive for IntStream. That will be hopefully fixed by SONARJAVA-1478

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