Reverse String

Write a function that takes a string as input and returns the string reversed.

Example 1:

Input: "hello"
Output: "olleh"

Example 2:

Input: "A man, a plan, a canal: Panama"
Output: "amanaP :lanac a ,nalp a ,nam A"

class Solution {
    public String reverseString(String s) {
        if(s == null || s.length() == 0)
            return s;
        
        char[] charArr = s.toCharArray();
        
        int i = 0, j = charArr.length-1;
        
        while(i < j){
            char tmp = charArr[i];
            charArr[i] = charArr[j];
            charArr[j] = tmp;
            i++;
            j--;
        }
        
        return new String(charArr);
    }
}