题解 | #字符串加解密#

import java.util.Scanner;

// 注意类名必须为 Main, 不要有任何 package xxx 信息
public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        String encryptStr = sc.nextLine();
        char[] charArray = encryptStr.toCharArray();
        for (int i = 0; i < charArray.length; i++) {
            System.out.print(encryptChar(charArray[i]));
        }
        System.out.println();

        String decryptStr = sc.nextLine();
        charArray = decryptStr.toCharArray();
        for (int i = 0; i < charArray.length; i++) {
            System.out.print(decryptChar(charArray[i]));
        }
    }

    public static char encryptChar(char c) {
        if (c >= 'a' && c < 'z') {
            return (char) (c - 'a' + 'A' + 1);
        } else if (c >= 'A' && c < 'Z') {
            return (char) (c - 'A' + 'a' + 1);
        } else if (c >= '0' && c < '9') {
            return (char) (c + 1);
        } else if (c == 'z') {
            return 'A';
        } else if (c == 'Z') {
            return 'a';
        } else if (c == '9') {
            return '0';
        } else {
            return c;
        }
    }

    public static char decryptChar(char c) {
        if (c > 'a' && c <= 'z') {
            return (char) (c - 'a' + 'A' - 1);
        } else if (c > 'A' && c <= 'Z') {
            return (char) (c - 'A' + 'a' - 1);
        } else if (c > '0' && c <= '9') {
            return (char) (c - 1);
        } else if (c == 'A') {
            return 'z';
        } else if (c == 'a') {
            return 'Z';
        } else if (c == '0') {
            return '9';
        } else {
            return c;
        }
    }
}