在C＃中的对象列表中使用RemoveAll不删除项目

Question

我有一个消息列表。 我想浏览一下列表并执行以下操作：

1. 如果SenderID = 100，则将ShowInSenderInbox和ShowInSenderOutbox值设置为零。
2. 如果ReceiverID = 100，则将ShowInReceiverInbox值设置为零。 一旦满足以上两个条件，那么我要检查以下内容：
3. 如果ShowInSenderInbox == 0 && ShowInSenderOutbox == 0 && ShowInReceiverInbox == 0，则从列表中删除该项目。

当前，我的代码将ShowInSenderInbox，ShowInSenderOutbox和ShowInReceiverInbox的值相应地设置为零。 但是，它不会从列表中删除与条件3匹配的项目。

这是完整的代码：

public class Message
{
   public int MessageID { get; set; }
   public int SenderID { get; set; }
   public int ReceiverID { get; set; }
   public int ShowInSenderInbox { get; set; }
   public int ShowInSenderOutbox { get; set; }
   public int ShowInReceiverInbox { get; set; }
}

public bool GetItem(Message I)
{           
   if (I.SenderID == 100)
   {
      I.ShowInSenderInbox = 0;
      I.ShowInSenderOutbox = 0;
   }
   else if (I.ReceiverID == 100)
   {
      I.ShowInReceiverInbox = 0;
   }

   if (I.ShowInSenderInbox == 0 && I.ShowInSenderOutbox == 0 && I.ShowInReceiverInbox == 0)
   {
      return true;
   }
   else
   {
      return false;
   }                             
}


List<Message> messages = new List<Message>() {
    new Message { MessageID=1, SenderID=100, ReceiverID=200, ShowInSenderInbox=1, ShowInSenderOutbox=1, ShowInReceiverInbox=1 },
    new Message { MessageID=2, SenderID=101, ReceiverID=300, ShowInSenderInbox=1, ShowInSenderOutbox=1, ShowInReceiverInbox=1 },
    new Message { MessageID=3, SenderID=102, ReceiverID=100, ShowInSenderInbox=1, ShowInSenderOutbox=0, ShowInReceiverInbox=0 },
    new Message { MessageID=4, SenderID=100, ReceiverID=101, ShowInSenderInbox=0, ShowInSenderOutbox=1, ShowInReceiverInbox=0 },
    new Message { MessageID=5, SenderID=200, ReceiverID=300, ShowInSenderInbox=1, ShowInSenderOutbox=0, ShowInReceiverInbox=0 },
    new Message { MessageID=9, SenderID=100, ReceiverID=400, ShowInSenderInbox=1, ShowInSenderOutbox=1, ShowInReceiverInbox=1 },
    new Message { MessageID=11, SenderID=400, ReceiverID=100, ShowInSenderInbox=1, ShowInSenderOutbox=1, ShowInReceiverInbox=0 },
    new Message { MessageID=21, SenderID=80, ReceiverID=150, ShowInSenderInbox=1, ShowInSenderOutbox=0, ShowInReceiverInbox=1 },
    new Message { MessageID=23, SenderID=100, ReceiverID=300, ShowInSenderInbox=1, ShowInSenderOutbox=1, ShowInReceiverInbox=0 },
    new Message { MessageID=28, SenderID=50, ReceiverID=90, ShowInSenderInbox=1, ShowInSenderOutbox=0, ShowInReceiverInbox=1 },
    new Message { MessageID=29, SenderID=100, ReceiverID=900, ShowInSenderInbox=1, ShowInSenderOutbox=1, ShowInReceiverInbox=1 },
    new Message { MessageID=22, SenderID=500, ReceiverID=900, ShowInSenderInbox=0, ShowInSenderOutbox=0, ShowInReceiverInbox=0 },
    new Message { MessageID=39, SenderID=409, ReceiverID=500, ShowInSenderInbox=0, ShowInSenderOutbox=0, ShowInReceiverInbox=0 },
    new Message { MessageID=41, SenderID=105, ReceiverID=900, ShowInSenderInbox=0, ShowInSenderOutbox=0, ShowInReceiverInbox=0 }
 };

( from item in messages
  where item.SenderID == 100 || item.ReceiverID == 100
  select item )
               .ToList()
               .RemoveAll( I => GetItem(I) );

http://www.geocities.ws/sonnyk2015/dosscreen2.png

Answer 1

只需添加此行：

messages.RemoveAll(i => i.ShowInSenderInbox == 0 && i.ShowInSenderOutbox == 0 && i.ShowInReceiverInbox == 0);