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 in = new Scanner(System.in);
        String s1 = in.nextLine();
        String s2 = in.nextLine();
	  
        System.out.println(encrypt(s1));
        System.out.println(decrypt(s2));

    }

    // 加密
    public static String encrypt(String str) {
        char[] ch = str.toCharArray();
        for (int i = 0; i < ch.length; i++) {
            if (Character.isUpperCase(ch[i])) {
                ch[i] = (char) ('a' + ((Character.toLowerCase(ch[i]) - 'a' + 1) % 26));
            } else if (Character.isLowerCase(ch[i])) {
                ch[i] = (char) ('A' + ((Character.toUpperCase(ch[i]) - 'A' + 1) % 26));
            } else if (Character.isDigit(ch[i])) {
                if (ch[i] == '9') {
                    ch[i] = '0';
                } else {
                    ch[i] = (char) (ch[i] + 1);
                }
            }
        }
        return String.valueOf(ch);
    }
    // 解密
    public static String decrypt(String str) {
        char[] ch = str.toCharArray();
        for (int i = 0; i < ch.length; i++) {
            if (Character.isUpperCase(ch[i])) {
                ch[i] = (char) ('a' + ((Character.toLowerCase(ch[i]) - 'a' - 1 + 26) % 26));
            } else if (Character.isLowerCase(ch[i])) {
                ch[i] = (char) ('A' + ((Character.toUpperCase(ch[i]) - 'A' - 1 + 26) % 26));
            } else if (Character.isDigit(ch[i])) {
                if (ch[i] == '0') {
                    ch[i] = '9';
                } else {
                    ch[i] = (char) (ch[i] - 1);
                }
            }
        }
        return String.valueOf(ch);
    }
}