Very simple input reception in Java

I hadn't written it for a while, so I completely forgot. It is a memo that receives input by brain death.

Common items

Call the Scanner with the import statement.


import java.util.*;

Pass to the Scanner class.


Scanner sc = new Scanner(;

Receiving strings

Let $ S $ be a character string.


String S =;
String S = sc.nextLine();

However, next recognizes the input value up to the line feed, and nextLine recognizes up to the blank. For example

S_1 S_2 S_3

Is input, next reads $ S_1 $ $ S_2 $, and nextLine reads $ S_1 $.

Reading numbers

Let $ x $ be a number. It seems that parsing with ʻInteger.parseInt () is about twice as fast.


int x = Integer.parseInt(sc.nextLine());
int x = sc.nextInt();

Read array

Let $ V_1, V_2, \ cdots V_n $ be the array V.


Integer V[] = new Integer[N];
for (int i=0; i<N; i++) {
    V[i] = sc.nextInt();

Readability is low if:


String a = sc.nextLine();
String[] b = a.split(" ");
int[] c = Stream.of(b).mapToInt(Integer::parseInt).toArray();

Read List

Let $ V_1, V_2, \ cdots V_n $ be ListV.


ArrayList<String> V = new ArrayList<String>();
for (int i=0; i<N; i++) {
    V[i] = sc.nextInt();

It seems that you can expect higher speed by making your own Scanner.

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