LeetCode - Rotate String

We are given two strings, A and B.

A shift on A consists of taking string A and moving the leftmost character to the rightmost position. For example, if A = 'abcde', then it will be 'bcdea' after one shift on A. Return True if and only if A can become B after some number of shifts on A.

Example 1:
Input: A = 'abcde', B = 'cdeab'
Output: true

Example 2:
Input: A = 'abcde', B = 'abced'
Output: false
Note:

A and B will have length at most 100.

class Solution {
    public boolean rotateString(String A, String B) {
        if(A == null || B == null || A.length() != B.length()){
            return false;
        }
        if(A.length() == 0 && B.length() == 0){
            return true;
        }

        int n = A.length();
　　　　　//轮数
        for(int i = 0; i< n; i++){
            boolean find = true;
　　　　　　　//每一个元素
            for(int j = 0; j < n; j++){
                int a = A.charAt(j);
                int newIndex = (n - i + j) % n;
                int b = B.charAt(newIndex);
                if(a != b){
                    find = false;
                    break;
                }
            }
            if(find){
                return true;
            }
        }
        return false;
    }
}