Reverse Words in a String III

Given a string, you need to reverse the order of characters in each word within a sentence while still preserving whitespace and initial word order.

Example 1:

Input: "Let's take LeetCode contest"
Output: "s'teL ekat edoCteeL tsetnoc"

Note: In the string, each word is separated by single space and there will not be any extra space in the string.

class Solution {
    public String reverseWords(String s) {
        if(s == null || s.length() == 0)
            return s;
        String []words = s.split(" ");
        StringBuilder result = new StringBuilder();
        for(String word : words){
            String newWord = reverseWord(word);
            result.append(newWord);
            result.append(" ");
        }
        return result.toString().substring(0, result.toString().length() - 1);
    }
    private String reverseWord(String word){
        char []arr = word.toCharArray();
        for(int i = 0, j = arr.length - 1; i <= j; i++, j--){
            char temp = arr[i];
            arr[i] = arr[j];
            arr[j] = temp;
        }
        return new String(arr);
    }
}