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 s1 = sc.nextLine();
        String s2 = sc.nextLine();
        System.out.println(encode(s1));
        System.out.println(decode(s2));
    }

    private static String encode(String str) {
        StringBuilder sb = new StringBuilder();
        for(int i=0; i<str.length(); i++){
            char c = str.charAt(i);
            if(c>='0' && c<='8') sb.append( (char)(c+1) );
            else if(c == '9') sb.append('0');
            else if(c == 'z') sb.append('A');
            else if(c == 'Z') sb.append('a');
            else if(c>='a' && c<='y') sb.append( (char)(toUpperCase(c)+1) );
            else if(c>='A' && c<='Y') sb.append( (char)(toLowerCase(c)+1) );
            else sb.append(c);
        }
        return sb.toString();
    }

    private static String decode(String str) {
        StringBuilder sb = new StringBuilder();
        for(int i=0; i<str.length(); i++){
            char c = str.charAt(i);
            if(c>='1' && c<='9') sb.append( (char)(c-1) );
            else if(c == '0') sb.append('9');
            else if(c == 'a') sb.append('Z');
            else if(c == 'A') sb.append('z');
            else if(c>='b' && c<='z') sb.append( (char)(toUpperCase(c)-1) );
            else if(c>='B' && c<='Z') sb.append( (char)(toLowerCase(c)-1) );
            else sb.append(c);
        }
        return sb.toString();
    }

    public static char toUpperCase(char c1) {
        int a = (int) c1;//将接收到的小写字符c1转换成int类型的数据给a
        int b = a - 32;  //a-32得出小写对应大写的ascll数值
        char bb = (char)b;//最后将b转换成char类型字符给bb
        return bb;        //返回bb；就是返回大写的字符
    }

    public static char toLowerCase(char c1) {
        int a = (int) c1;//将接收到的小写字符c1转换成int类型的数据给a
        int b = a + 32;  //a+32得出大写写对应小写的ascll数值
        char bb = (char)b;//最后将b转换成char类型字符给bb
        return bb;        //返回bb；就是返回字母小写的字符
    }
}