ADevGuide 
This Java solution for LeetCode 557, Reverse Words in a String III, shows how to reverse each word while preserving the original word order and spaces.
Problem Statement
Given a string s, reverse the order of characters in each word within a sentence while still preserving whitespace and initial word order.
Explanation
Input:
s = “Let’s take LeetCode contest”
Output:
“s’teL ekat edoCteeL tsetnoc”
Characters of every word is reversed.
Constraints
1 <= s.length <= 5 * 104s contains printable ASCII characters.s does not contain any leading or trailing spaces.- There is at least one word inÂ
s. - All the words inÂ
s are separated by a single space.
Test Cases
Test Case 1
Input:
s = “God Ding”
Output:
“doG gniD”
Solution
Leetcode Link
https://leetcode.com/problems/reverse-words-in-a-string-iii/