(String)将一个String里面的单词反转

e.g.  i love java    return   java love i

 public static String reverseStr(String str) {
		 String[] strs=str.split(" ");
		 StringBuilder sb=new StringBuilder();
		 for(int i=strs.length-1;i>=0;i--) {
			 sb.append(strs[i]+" ");
		 }
		 return sb.toString();
	 }