如何从 System.in / System.console() 构建 Java 8 流?
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How to build a Java 8 stream from System.in / System.console()?
提问by Georgy Ivanov
Given a file, we can transform it into a stream of strings using, e.g.,
给定一个文件,我们可以使用例如,将其转换为字符串流
Stream<String> lines = Files.lines(Paths.get("input.txt"))
Can we build a stream of lines from the standard input in a similar way?
我们可以以类似的方式从标准输入构建一个行流吗?
回答by Georgy Ivanov
A compilation of kocko's answer and Holger's comment:
kocko 的回答和 Holger 的评论的汇编:
BufferedReader in = new BufferedReader(new InputStreamReader(System.in));
Stream<String> stream = in.lines().limit(numberOfLinesToBeRead);
回答by Adrian
you can use just Scanner
in combination with Stream::generate
:
您可以仅Scanner
与Stream::generate
以下组合使用:
Scanner in = new Scanner(System.in);
List<String> input = Stream.generate(in::next)
.limit(numberOfLinesToBeRead)
.collect(Collectors.toList());
or (to avoid NoSuchElementException
if user terminates before limit is reached):
或(避免NoSuchElementException
用户在达到限制之前终止):
Iterable<String> it = () -> new Scanner(System.in);
List<String> input = StreamSupport.stream(it.spliterator(), false)
.limit(numberOfLinesToBeRead)
.collect(Collectors.toList());
回答by Konstantin Yovkov
Usually the standard input is read line by line, so what you can do is store all the read line into a collection, and then create a Stream
that operates on it.
通常标准输入是逐行读取的,所以你可以做的就是将所有读取的行存储到一个集合中,然后创建一个对其Stream
进行操作的集合。
For example:
例如:
List<String> allReadLines = new ArrayList<String>();
BufferedReader in = new BufferedReader(new InputStreamReader(System.in));
String s;
while ((s = in.readLine()) != null && s.length() != 0) {
allReadLines.add(s);
}
Stream<String> stream = allReadLines.stream();