[백준] 9086 문자열

https://www.acmicpc.net/problem/9086

9086번: 문자열

 

방법1

import java.util.Scanner;

public class Main {
    public static void main(String[] args){
        Scanner sc = new Scanner(System.in);
        StringBuilder sb = new StringBuilder();

        int n = sc.nextInt();
        for(int i = 0; i<n; i++){
            String word = sc.next();
            int idx = word.length()-1;
            sb.append(word.charAt(0));
            sb.append(word.charAt(idx)+ "\n");
        }
        System.out.println(sb);
    }
}

 

잘못된 풀이

import java.util.Scanner;

public class Main {
    public static void main(String[] args){
        Scanner sc = new Scanner(System.in);
        String word = sc.next();
        int idx = word.length()-1;
        System.out.println(word.charAt(0) + word.charAt(idx));
    }
}

입출력값

word
219

word.charAt(0) + word.charAt(idx)를 연산하면 숫자가 출력되는 이유?

char 2개를 더한 아스키코드값이 나오므로 각각 출력해준다.

 

방법2

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;

public class Main {
    public static void main(String[] args) throws IOException {
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
        int n = Integer.parseInt(br.readLine());

        for(int i=0; i<n; i++){
            String word = br.readLine();
            int idx = word.length()-1;

            System.out.println(String.valueOf(word.charAt(0)) + String.valueOf(word.charAt(idx)));
        }
    }
}

String.valueOf()와 toString()의 차이점.