题解 | #字符串加解密#

import java.util.Scanner;

public class Main {
    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        String en = in.nextLine(); //待加密字符串
        String de = in.nextLine(); //待解密字符串
        System.out.println(encrypt(en));
        System.out.println(decrypt(de));


    }

    public static String encrypt(String en) {
        char[] chars = en.toCharArray();
        for (int i = 0; i < chars.length; i++) {
            chars[i] = encryptWord(chars[i]);
        }
        return new String(chars);
    }

    public static char encryptWord(char c) {
        if (Character.isLetter(c)) {
            if (c == 'Z') {
                return 'a';
            }
            if (c == 'z') {
                return 'A';
            }
            c += 1;
            if (c >= 'a' && c <= 'z') {
                return Character.toUpperCase(c);
            }
            return Character.toLowerCase(c);
        }

        if (c == '9') {
            return '0';
        }
        c += 1;
        return c;
    }
    
    public static String decrypt(String en) {
        char[] chars = en.toCharArray();
        for (int i = 0; i < chars.length; i++) {
            chars[i] = decryptWord(chars[i]);
        }
        return new String(chars);
    }

    public static char decryptWord(char c) {
        if (Character.isLetter(c)) {
            if (c == 'a') {
                return 'Z';
            }
            if (c == 'A') {
                return 'z';
            }
            c -= 1;
            if (c >= 'a' && c <= 'z') {
                return Character.toUpperCase(c);
            }
            return Character.toLowerCase(c);
        }

        if (c == '0') {
            return '9';
        }
        c -= 1;
        return c;
    }

}