Leetcode 344. Reverse String

public class Solution {    public String reverseString(String s) {        StringBuilder sb = new StringBuilder(s);        int low = 0, high = s.length()-1;                while (low < high) {            char tmp = sb.charAt(low);            sb.setCharAt(low, sb.charAt(high));            sb.setCharAt(high, tmp);            low++;            high--;        }                return sb.toString();    }}