流上的终端操作是否关闭源？ [英] Do terminal operations on streams close the source?

问题描述

考虑以下代码：

Path directory = Paths.get(/* some directory */);
Files.list(directory).forEach(System.out::println);

终端操作（如 forEach ）关闭已打开的基础文件？

Does a terminal operation (like forEach) close the underlying file that has been opened?

请参阅 Files.list ：

返回的流封装了DirectoryStream。如果需要及时处理文件系统资源，则应使用try-with-resources构造来确保在流操作完成后调用流的close方法。

The returned stream encapsulates a DirectoryStream. If timely disposal of file system resources is required, the try-with-resources construct should be used to ensure that the stream's close method is invoked after the stream operations are completed.

如果它没有调用 Stream.close（），那会是什么？然后是生成可维护代码时调用它的最佳替代方法？

If it doesn't call Stream.close(), what would then be the best alternative to call it while producing maintainable code?

推荐答案

终端运营商不会自动关闭流。考虑以下代码：

Terminal operators do NOT close the stream automatically. Consider this code:

Stream<Path> list = Files.list(directory).onClose(() -> System.out.println("Closed"));
list.forEach(System.out::println);

这不打印关闭。

但是，以下打印已关闭：

However, the following does print "Closed":

try (Stream<Path> list = Files.list(directory).onClose(() -> System.out.println("Closed"))) {
    list.forEach(System.out::println);
}

所以最好的方法是使用try-with-resources机制。

So the best way to do it is to use the try-with-resources mechanism.

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