Read input from console in Kotlin

This post will discuss how to read input from the console in Kotlin.

1. Using `Scanner`

A simple solution is to use the Scanner class for reading input from the console. It splits the input into tokens using whitespace as a separator, which then can be converted into different data types with the corresponding .next*() functions:

import java.util.Scanner

fun main() {

val scanner = Scanner(System.`in`)

println(scanner.nextLine()) // read the whole line

println(scanner.nextInt()) // get the next integer token

println(scanner.next()) // get the next string token

println(scanner.nextDouble()) // get the next double token

println(scanner.nextLong()) // get the next long token

scanner.close() // finally, close the scanner

}

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2. Using `BufferedReader`

We can achieve better performance using the BufferedReader class. The idea is to read the whole line as a string using the readLine() function, and convert it into different data types using the standard conversion functions provided by the String class.

import java.io.BufferedReader

import java.io.IOException

import java.io.InputStreamReader

fun main() {

try {

val br = BufferedReader(InputStreamReader(System.`in`))

println(br.readLine()) // read the whole line

println(br.readLine().toDouble()) // get double

println(br.readLine().toLong()) // get long

br.close() // finally, close the stream

} catch (e: IOException) {

e.printStackTrace()

}

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If the input is an integer, we can directly call the read() function, as shown below.

import java.io.BufferedReader

import java.io.IOException

import java.io.InputStreamReader

fun main() {

try {

val br = BufferedReader(InputStreamReader(System.`in`))

println(br.read()) // get integer

br.close() // close the stream

} catch (e: IOException) {

e.printStackTrace()

}

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3. Using `Console`

Finally, we can get access to the character-based console to read input from it. The System.console() function returns the Console object associated with the current Java virtual machine.

fun main() {

val console = System.console()

if (console != null) {

println(console.readLine()) // read the whole line

println(console.readLine().toDouble()) // get double

println(console.readLine().toInt()) // get integer

}

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That’s all about reading input from the console in Kotlin.

Read input from console in Kotlin

1. Using Scanner

2. Using BufferedReader

3. Using Console

Share this:

1. Using `Scanner`

2. Using `BufferedReader`

3. Using `Console`