Read a string from standard input in Java

This post will discuss how to read a string from standard input (System.in) using Scanner and BufferedReader in Java. Since a single line of input may contain multiple values, split the line into string tokens.

1. Using `Scanner`

A simple solution is to use the Scanner class for reading a line from System.in. A Scanner breaks its input into tokens using a delimiter pattern, which by default matches whitespace.

import java.util.Arrays;

import java.util.Scanner;

class Main

{

// Read a string from the standard input using `Scanner`

public static void main(String[] args)

{

Scanner scanner = new Scanner(System.in);

String[] tokens = scanner.nextLine().split(" ");

System.out.println(Arrays.asList(tokens));

scanner.close();

}

Download Code

We can also use StringTokenizer with the Scanner in place of String.split() to split the input as StringTokenizer is much faster.

import java.util.StringTokenizer;

import java.util.Scanner;

import java.util.List;

import java.util.ArrayList;

class Main

{

// Read a string from the standard input using `Scanner`

public static void main(String[] args)

{

List<String> tokens = new ArrayList<>();

Scanner scanner = new Scanner(System.in);

StringTokenizer st = new StringTokenizer(scanner.nextLine());

while (st != null && st.hasMoreElements()) {

tokens.add(st.nextToken());

}

System.out.println(tokens);

scanner.close();

}

Download Code

We can also use the Scanner.next() method to convert the resulting tokens into string values, as shown below. Here, hasNext() returns true if this scanner has another token left.

import java.util.ArrayList;

import java.util.List;

import java.util.Scanner;

class Main

{

public static void main(String[] args)

{

List<String> tokens = new ArrayList<>();

Scanner scanner = new Scanner(System.in);

while (scanner.hasNext()) {

tokens.add(scanner.next());

}

System.out.println(tokens);

scanner.close();

}

Download Code

2. Using `BufferedReader`

Although Scanner is very convenient for parsing the input, we can speed up things a little by using the BufferedReader and StringTokenizer combo in Java, which is much faster than the Scanner.

In the following program, readLine() reads a line of text which is terminated by any one of a carriage return ('\r'), line feed ('\n'), or a '\r\n'.

import java.io.BufferedReader;

import java.io.IOException;

import java.io.InputStreamReader;

import java.util.ArrayList;

import java.util.List;

import java.util.StringTokenizer;

class Main

{

// Read a string from the standard input using `BufferedReader`

public static void main(String[] args)

{

List<String> tokens = new ArrayList<>();

BufferedReader br = null;

try {

br = new BufferedReader(new InputStreamReader(System.in));

StringTokenizer st = new StringTokenizer(br.readLine());

while (st != null && st.hasMoreElements()) {

tokens.add(st.nextToken());

}

System.out.println(tokens);

}

catch (IOException e) {

System.out.println(e);

}

Download Code

That’s all about reading a string from standard input in Java.

Read a string from standard input in Java

1. Using Scanner

2. Using BufferedReader

Share this:

1. Using `Scanner`

2. Using `BufferedReader`