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 str1 = in.next(); // 加密前的字符串
        String str2 = in.next(); // 加密后的字符串

        System.out.println(jmString(str1));
        System.out.println(jmBackString(str2));

    }

    // 加密方法
    private static String jmString(String str1){
        
       char[] schar = str1.toCharArray();
       char[] result = new char[schar.length];
       for(int i = 0; i < schar.length ; i++){

            if(Character.isUpperCase(schar[i])){ // 大写字母时

                 if('Z' ==  schar[i]){
                     result[i] = 'a'; 
                 } else {
                    result[i] = (char)(schar[i] + 33  );
                 }
                 
            } else if(Character.isLowerCase(schar[i])){ // 小字母时

              if('z' ==  schar[i]){
                     result[i] = 'A'; 
                 } else {
                    result[i] = (char)(schar[i] - 31);
                 }

            } else if(Character.isDigit(schar[i])){ // 数字
                 if('9' == schar[i] ){
                    result[i] = '0'; 
                 } else {
                     result[i] = (char) (Integer.valueOf(schar[i]) + 1 );
                 }

            } else {
                result[i] = schar[i];
            }

       }
  
        return String.valueOf(result);
    }

     // 解密方法
    private static String jmBackString(String str1){
        
       char[] schar = str1.toCharArray();
       char[] result = new char[schar.length];
       for(int i = 0; i < schar.length ; i++){

            if(Character.isUpperCase(schar[i])){ // 大写字母时

                 if('A' ==  schar[i]){
                     result[i] = 'z'; 
                 } else {
                    result[i] = (char)(schar[i] + 31 );
                 }
                 
            } else if(Character.isLowerCase(schar[i])){ // 小字母时

              if('a' ==  schar[i]){
                     result[i] = 'Z'; 
                 } else {
                    result[i] = (char)(schar[i] - 33);
                 }

            } else if(Character.isDigit(schar[i])){ // 数字
                 if('0' == Integer.valueOf(schar[i])){
                    result[i] = '9'; 
                 } else {
                     result[i] = (char) (Integer.valueOf(schar[i]) - 1 );
                 }

            } else {
                result[i] = schar[i];
            }

       }
  
        return String.valueOf(result);
    }
}