如何创建用户定义的集合

public class User { public User ( ) { } public User ( String userName , String password ) { this.userName = userName; this.password = password; } private String password; public String Password { get { return password; } set { password = value; } } private String userName; public String UserName { get { return userName; } set { userName = value; } } 

 public class UsersCollection : CollectionBase , IEnumerable , IEnumerator { private int index = -1; public UsersCollection ( ) { this.index = -1; } public void Add ( User user ) { /* * Example for applying business Logic * */ if ( user != null ) { throw new Exception ( "Your passed User Object is null" ); } if ( user.Password.Length < 8 ) { throw new Exception ( "User's password can not be less than 8 characters" ); } /* * Normal behaviour of a Collection */ this.List.Add ( user ); } public void Remove ( User user ) { this.List.Remove ( user ); } public User this [ int index ] { get { return ( User ) this.List [ index ]; } set { this.List [ index ] = value; } }  #region IEnumerable Members IEnumerator IEnumerable.GetEnumerator ( ) { return this; }  #endregion  #region IEnumerator Members public Object Current { get { return this.List [ index ]; } } public bool MoveNext ( ) { this.index++; return ( this.index < this.List.Count ); } public void Reset ( ) { this.index = -1; }  #endregion public void Save ( UsersCollection collection ) { try { /* * Insert all items of */ } catch ( Exception e ) { /* * if you get an error in between Rollback */ throw e; } finally { } } }