import java.util.Scanner; public class Main{ public static void main(String[] args){ Scanner sc = new Scanner(System.in); StringBuilder sb = new StringBuilder(); String s = sc.next(); sb.append(s); sb.reverse(); String result = sb.toString(); if(s.equals(result)){ System.out.println("YES"); }else{ System.out.println("NO"); } } }java可以用StringBuilder来解决。