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 cla         


        

Answer 1

A recursive version (the compiler detects a tail recursion for improved heap usage),

def read: Unit = {
  val s = scala.io.StdIn.readLine()
  println(s)
  if (s.isEmpty) () else read 
}

Note the use of io.StdIn from Scala 2.11 . Also note with this approach we can accumulate user input in a collection that is eventually returned -- in addition to be printed out. Namely,

import annotation.tailrec

def read: Seq[String]= {

  @tailrec
  def reread(xs: Seq[String]): Seq[String] = {
    val s = StdIn.readLine()
    println(s)
    if (s.isEmpty()) xs else reread(s +: xs) 
  }

  reread(Seq[String]())
}