如何在 Scala 中获取用户的输入？

From the Scala maling list (formatting and links were updated):

Short answer:

readInt

Long answer:

If you want to read from the terminal, check out Console.scala. You can use these functions like so:

Console.readInt

Also, for your convenience, Predef.scala automatically defines some shortcuts to functions in Console. Since stuff in Predef is always and everywhere imported automatically, you can use them like so:

readInt

please try

scala> readint

please try this method

In Scala 2.11 use

scala.io.StdIn.readLine()

instead of the deprecated Console.readLine.

Here is a standard way to read Integer values

val a = scala.io.StdIn.readInt()
println("The value of a is " + a)

similarly

def readBoolean(): Boolean

Reads a Boolean value from an entire line from stdin.

def readByte(): Byte

Reads a Byte value from an entire line from stdin.

def readChar(): Char

Reads a Char value from an entire line from stdin.

def readDouble(): Double

Reads a Double value from an entire line from stdin.

def readFloat(): Float

Reads a Float value from an entire line from stdin.

def readInt(): Int

Reads an Int value from an entire line from stdin.

def readLine(text: String, args: Any*): String

Prints formatted text to stdout and reads a full line from stdin.

def readLine(): String

Reads a full line from stdin.

def readLong(): Long

Reads a Long value from an entire line from stdin.

def readShort(): Short

Reads a Short value from an entire line from stdin.

def readf(format: String): List[Any]

Reads in structured input from stdin as specified by the format specifier.

def readf1(format: String): Any

Reads in structured input from stdin as specified by the format specifier, returning only the first value extracted, according to the format specification.

def readf2(format: String): (Any, Any)

Reads in structured input from stdin as specified by the format specifier, returning only the first two values extracted, according to the format specification.

def readf3(format: String): (Any, Any, Any)

Reads in structured input from stdin as specified by the format specifier, returning only the first three values extracted, according to the format specification.

Similarly if you want to read multiple user inputs from the same line ex: name, age, weight you can use the Scanner object

import java.util.Scanner


// simulated input
val input = "Joe 33 200.0"
val line = new Scanner(input)
val name = line.next
val age = line.nextInt
val weight = line.nextDouble

abridged from Scala Cookbook: Recipes for Object-Oriented and Functional Programming by Alvin Alexander

object InputTest extends App{


println("Type something : ")
val input = scala.io.StdIn.readLine()
println("Did you type this ? " + input)


}

This way you can ask input.

scala.io.StdIn.readLine()

readLine() lets you prompt the user and read their input as a String

val name = readLine("What's your name? ")

Simple Example for Reading Input from User

val scanner = new java.util.Scanner(System.in)


scala> println("What is your name") What is your name


scala> val name = scanner.nextLine()
name: String = VIRAJ


scala> println(s"My Name is $name")
My Name is VIRAJ

Also we can use Read Line

val name = readLine("What is your name ")
What is your name name: String = Viraj

In Scala 2:

import java.io._
object Test {
// Read user input, output
def main(args: Array[String]) {


// create a file writer
var writer = new PrintWriter(new File("output.txt"))


// read an int from standard input
print("Enter the number of lines to read in: ")
val x: Int = scala.io.StdIn.readLine.toInt


// read in x number of lines from standard input
var i=0
while (i < x) {
var str: String = scala.io.StdIn.readLine
writer.write(str + "\n")
i = i + 1
}


// close the writer
writer.close
}
}

This code gets input from user and outputs it:

[input] Enter the number of lines to read in: 2
one
two


[output] output.txt
one
two

You can take a user String input using readLine().

import scala.io.StdIn._


object q1 {
def main(args:Array[String]):Unit={
println("Enter your name : ")
val a = readLine()
println("My name is : "+a)
}
}

Or you can use the scanner class to take user input.

import java.util.Scanner;


object q1 {
def main(args:Array[String]):Unit={
val scanner = new Scanner(System.in)
println("Enter your name : ")
val a = scanner.nextLine()
println("My name is : "+a)
}
}

Using a thread to poll the input-readLine:


// keystop1.sc


// In Scala- or SBT console/Quick-REPL: :load keystop1.sc
// As Script: scala -savecompiled keystop1.sc


@volatile var isRunning = true
@volatile var isPause = false


val tInput: Thread = new Thread {
override def run: Unit = {
var status = ""
while (isRunning) {
this.synchronized {
status = scala.io.StdIn.readLine()
status match {
case "s" => isRunning = false
case "p" => isPause = true
case "r" => isRunning = true;isPause = false
case _ => isRunning = false;isPause = false
}
println(s"New status is: $status")
}
}
}
}


tInput.start


var count = 0
var pauseCount = 0


while (isRunning && count < 10){
println(s"still running long lasting job! $count")
if (count % 3 == 0) println("(Please press [each + ENTER]: s to stop, p to pause, r to run again!)")
count += 1
Thread sleep(2000) // simulating heavy computation
while (isPause){
println(s"Taking a break ... $pauseCount")
Thread sleep(1000)
pauseCount += 1
if (pauseCount >= 10){
isPause = false
pauseCount = 0
println(s"Taking a break ... timeout occurred!")
}
}
}
isRunning = false
println(s"Computation stopped, please press Enter!")
tInput.join()
println(s"Ok, thank you, good bye!")