[Java]프로그래머스 Lv. 0 대문자와 소문자

https://school.programmers.co.kr/learn/courses/30/lessons/120893

프로그래머스

나의 풀이

class Solution {
    public String solution(String my_string) {
        StringBuilder sb = new StringBuilder();
        for (char c : my_string.toCharArray()){
            if (Character.isLowerCase(c)) c = Character.toUpperCase(c);
            else c = Character.toLowerCase(c);
            sb.append(c);
        }
        return sb.toString();
    }
}

다른 풀이

class Solution {
    public String solution(String s) {
        String answer = "";

        for(int i=0;i<s.length();i++){
            if(s.charAt(i)>=97 && s.charAt(i)<=122){
                answer += (char)(s.charAt(i)-32);
            } else if(s.charAt(i)>=65 && s.charAt(i)<=90){
                answer += (char)(s.charAt(i)+32);
            } else {
                answer += s.charAt(i);
            }
        }

        return answer;
    }
}

import java.util.stream.Collectors;

class Solution {
    public String solution(String myString) {
        return myString.chars().mapToObj(operand -> String.valueOf((char) (Character.isLowerCase(operand) ? Character.toUpperCase(operand) : Character.toLowerCase(operand)))).collect(Collectors.joining());
    }
}