/***
 * 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.length() == 0)
            return 0;
        s = s.trim();
        for (int i = s.length(); i > 0; i--){
            if (s.charAt(i - 1) == ' ')
                return s.length() - i;
        }
        return s.length();
    }
}

add LengthofLastWord.java