如何逐行读取标准输入？ [英] How to read from standard input line by line?

问题描述

从标准输入逐行阅读的Scala配方是什么？类似于等效的java代码：

What's the Scala recipe for reading line by line from the standard input ? Something like the equivalent java code :

import java.util.Scanner; 

public class ScannerTest {
    public static void main(String args[]) {
        Scanner sc = new Scanner(System.in);
        while(sc.hasNext()){
            System.out.println(sc.nextLine());
        }
    }
}

推荐答案

最直接的方法只使用 readLine（），它是 Predef 的一部分。然而，这需要检查最终的空值是否相当丑陋：

The most straight-forward looking approach will just use readLine() which is part of Predef. however that is rather ugly as you need to check for eventual null value:

object ScannerTest {
  def main(args: Array[String]) {
    var ok = true
    while (ok) {
      val ln = readLine()
      ok = ln != null
      if (ok) println(ln)
    }
  }
}

这是如此冗长，你宁愿使用 java.util.Scanner 。

this is so verbose, you'd rather use java.util.Scanner instead.

我认为更漂亮方法将使用 scala.io.Source ：

I think a more pretty approach will use scala.io.Source:

object ScannerTest {
  def main(args: Array[String]) {
    for (ln <- io.Source.stdin.getLines) println(ln)
  }
}

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