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.

Example
Given s = “Hello World”, return 5.

public class Solution {
    /**
     * @param s A string
     * @return the length of last word
     */
    public int lengthOfLastWord(String s) {
        if (s == null | s.isEmpty()) return 0;

        // trim right space去除右边的空格
        int begin = 0,end = s.length();
        while(end>0&&s.charAt(end-1)==' '){
            end--;
        }
        for(int i=0;i<end;i++){
            if(s.charAt(i)==' '){
                begin=i+1;
            }
        }
        return end-begin;
        //计算最后一个单词的长度
    }
}