题解 | #字符串加解密#

主要用字符串每个字符挨个判断

public class Main{
    public static void main(String[] args){
        Scanner sc = new Scanner(System.in);
        while(sc.hasNext()){
            String str1 = sc.nextLine();
            System.out.println(encrypt(str1));
            String str2 = sc.nextLine();
            System.out.println(decrypt(str2));
        }

    }
    public static String encrypt(String str){
        StringBuffer sb = new StringBuffer();
        for(int i=0;i<str.length();i++){
            char ch = str.charAt(i);
            if(ch>='a'&&ch<'z'){
                sb.append((char)(ch-'a'+'A'+1));
            }
            else if(ch=='z'){
                sb.append('A');
            }
            else if(ch>='A'&&ch<'Z'){
                sb.append((char)(ch-'A'+'a'+1));
            }
            else if(ch=='Z'){
                sb.append('a');
            }
            else if(ch>='0'&&ch<'9'){
                sb.append((char)(ch+1));
            }
            else if(ch=='9'){
                sb.append('0');
            }
        }
        return sb.toString();
    }
    public static String decrypt(String str){
        StringBuffer sb = new StringBuffer();
        for(int i=0;i<str.length();i++){
            char ch = str.charAt(i);
            if(ch>'a'&&ch<='z'){
                sb.append((char)(ch-'a'+'A'-1));
            }
            else if(ch=='a'){
                sb.append('Z');
            }
            else if(ch>'A'&&ch<='Z'){
                sb.append((char)(ch-'A'+'a'-1));
            }
            else if(ch=='A'){
                sb.append('z');
            }
            else if(ch>'0'&&ch<='9'){
                sb.append((char)(ch-1));
            }
            else if(ch=='0'){
                sb.append('9');
            }
        }
        return sb.toString();
    }
}