//判断是否单双号，S单号，D双号
  	public static String checkCarLicense(String carLicense) {
  		for (int i = 0; i < carLicense.length(); i++) {
  			String lastnum=carLicense.substring(carLicense.length()-(i+1),carLicense.length()-i);
		    System.out.println(lastnum);
			boolean isnum=isNum(lastnum);//判断是不是数字
			if(isnum) {
				//是数字，判断单双
				int temp = Integer.valueOf(lastnum);
				if(temp==0){
					int a=0;
				}
				if(temp%2!=0){
					//单数
					return "S";
				}else{
					return "D";
				}
			}
		}
  		//全是字母，基本不可能
  		return null;
  	}
  	 public static boolean isNum(String str){
         Pattern pattern = Pattern.compile("[0-9]*");
         Matcher isNum = pattern.matcher(str);
         if( !isNum.matches() ){
             return false;
         }
         return true;
  	 }