事件不叫C＃

Question

我目前正在製作一個NFC圖書館，當我成功讀取一張卡片時，我需要舉辦一個活動。

在我MainProject我調用庫這樣的：

reader = new NfcReader(); 
    if (reader.Initialize()) 
    { 
     reader.UidReceived += (s, args) => 
      DisplayText(String.Format("UID received: {0}", args.Uid)); 
    } 

我的圖書館：

public class NfcReader 
{ 
    private SCardMonitor monitor; 
    public event EventHandler<NfcReaderEventArgs> UidReceived; 

    public bool Initialize() 
    { 
     // When a card is inserted, an event is raised 
     // then I want to read the Uid of the card 
     monitor = new SCardMonitor(new SCardContext(), SCardScope.System); 
     monitor.CardInserted += (s,a) => GetUid(a.ReaderName); 
     return true; 
    } 

    private void GetUid(string readerName) 
    { 
     string uid = MyUidGetter(readerName); 
     OnUidReceived(uid); 
    } 

    private void OnUidReceived(string uid) 
    { 
     var handler = UidReceived; 
     if (handler == null) 
     { 
      handler(this, new NfcReaderEventArgs(uid)); 
     } 
    } 
} 

通過handler(this, new NfcReaderEventArgs(uid));調試步驟，但DisplayText方法不會被調用。有任何想法嗎？

Answer 1

我想這是一個錯誤，你檢查處理程序爲空？ ;）

也許你的Initialize返回false。調試器完全通過，因爲它不會調用任何東西。這是由if確定的。

我建議您使用handler！= null來確保Initialize返回true。