How to read from standard input line by line?

Question

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());         }     } } 

Answer 1

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)     }   } } 

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

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)   } }