Java的構造函數最後一個變量賦值

public class User 
{ 
    private final String _first_name; 
    private final String _last_name; 
    private final String _org_ID; 
    private final TimeZone _time_zone; 
    private final InternetAddress _email; 
    private final Date _last_login; 
    private final Date _creation_date; 


     public User(final String org_ID, 
          final String username, 
          final String first_name, 
          final String last_name, 
          final List<String> roles, 
          final TimeZone time_zone, 
          final InternetAddress email, 
          final Date last_login, 
          final Date creation_date) 
     { 
      this(null, org_ID, username, first_name, last_name, roles, time_zone); 

      this._email = email; 
      this._last_login = last_login; 
      this._creation_date = creation_date; 
     }

編譯器給出了分別在3個變量賦值了以下錯誤：「變量_EMAIL可能已經被分配」Java的構造函數最後一個變量賦值

是編譯器無法分辨變量未設置在打電話給第一個ctor？我在這裏錯過了什麼？

來源

2010-07-28 J. Andrew Laughlin