LeetCode-Reverse Words in a String

public class Solution {
    public String reverseWords(String s) {
        if(s == null || s.length() == 0){
            return s;
        }
        Stack<String> stack = new Stack<>();
        StringBuilder sb = new StringBuilder();
        for(int i=0; i<s.length(); i++){
            char c = s.charAt(i);
            if(c != ‘ ‘){
                sb.append(c);
            }
            if((i == s.length() - 1 || c == ‘ ‘) && sb.length() != 0){
                stack.push(sb.toString());
                sb.delete(0,sb.length());
            }
        }
        int count = 0;
        while(!stack.isEmpty()){
            if(count == stack.size()-1){
                sb.append(stack.pop());
            }
            else{
                sb.append(stack.pop()+" ");
            }
        }
        return sb.toString();
    }
}