运用正则表达式之后代码量减少

  String qq="123456789";System.out.println(qq.matches("[1-9]\\d{5,19}"));

输入qq号

 public static void main(String[] args) {String qq="123456789";System.out.println(checkqq(qq));}public static boolean checkqq(String qq){int len=qq.length();if(len>20||len<6){}if()