import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.util.StringTokenizer;
public class SwapAlphabet {
public static void main(String[] args) throws IOException {
BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
StringTokenizer st = new StringTokenizer(br.readLine());
StringBuffer word = new StringBuffer(st.nextToken());
for (int i = 0; i < word.length(); i++) { // A: 65, a: 97, 32 차이 / Z: 90, z:122
if (65 <= word.charAt(i) && word.charAt(i) < 91)
word.replace(i, i + 1, Character.toString((char) (word.charAt(i) + 32)));
else if (97 <= word.charAt(i) && word.charAt(i) < 123)
word.replace(i, i + 1, Character.toString((char) (word.charAt(i) - 32)));
}
System.out.println(word.toString());
}
}
아스키 코드값 확인
해결 과정