32.翻转单词顺序列

题目描述：写程序将“student. a am I”反转成“I am a student”

public class Solution {    public String ReverseSentence(String str) {        if(str==null){            return null;        }        if(str.trim().equals("")){            return str;        }        String[] strArray = str.split(" ");        StringBuffer sb = new StringBuffer();        for(int i=strArray.length-1;i>=0;i--){            if(i==0){                sb.append(strArray[i]);            }else{                sb.append(strArray[i]);                sb.append(" ");            }        }        return sb.toString();    }}