Length of Last Word

Given a string s consists of upper/lower-case alphabets and empty space characters ' ', return the length of last word in the string.

If the last word does not exist, return 0.

Note: A word is defined as a character sequence consists of non-space characters only.

For example, 
Given s = "Hello World",
return 5.

public class Solution {    public int lengthOfLastWord(String s) {        if(s.equals(" ") || s.equals("") || s==null) return 0;/*      String ss=s.trim();        int index=ss.lastIndexOf(' ');        int res=ss.length()-index-1;        return res;*/        if(s.trim().equals("")) return 0;        String []arr=s.split(" ");        String last=arr[arr.length-1];        return last.length();    }}