給定一個字符串，逐個翻轉字符串中的每個單詞

示例:

輸入:
"the sky is blue",

輸出:
"blue is sky the".

 public  String reverseWords(String s) {
    	StringBuilder sb = new StringBuilder();
    	if(s == null || "".equals(s.trim())){
    		return "";
    	}else{
    		String [] strs = s.trim().split("\\s+");
    		int len = strs.length-1;
    		for(int i=len;i>=0;i--){
    			if(i == 0){
    				sb.append(strs[i]);
    			}else{
    				sb.append(strs[i]+" ");
    			}
    		}
    		return sb.toString();
    	}
    }

trim()去除字符串兩頭空格，split()的用法