值'1'不適用於'索引'

Question

這是我嘗試運行程序時收到的錯誤。 （請原諒，我的世界的背景下，這就是我試圖創建的重要組成部分）

下面是我試圖執行

int oldCount; 

    string RecentPlayer; 
    string val; 

    public void SetBalloonTip() 
    { 

     NewPlayerMessage.BalloonTipTitle = "A Player Has Joined!"; 

     NewPlayerMessage.BalloonTipText = RecentPlayer + " has joined your server " + ConfigKey.ServerName.GetString(); 
     NewPlayerMessage.BalloonTipIcon = ToolTipIcon.Info; 

    } 

    private void PlayerListUpdates_Tick(object sender, EventArgs e) 
    { 
       oldCount = playerList.Items.Count - 1; 
       if (oldCount < playerList.Items.Count) 
       { 
        if (playerList.Items.Count > 0) 
        { 
         RecentPlayer = playerList.Items[playerList.Items.Count].ToString(); 

         val = playerList.Items[playerList.Items.Count].ToString(); 
         NewPlayerMessage.Visible = true; 
         SetBalloonTip(); 
         NewPlayerMessage.ShowBalloonTip(50000); 

        } 

       } 
       else { 
        return; 
     } 

    } 

Answer 1

解決方案中的C＃代碼1 ：你需要記住，數組索引始終以Zero開始，以Count-1

結束替換此：

playerList.Items[playerList.Items.Count] 

這一點：

playerList.Items[playerList.Items.Count-1] 

OR

解決方案2：只需使用oldCount變量持有價值playerList.Items.Count - 1

替換此：

playerList.Items[playerList.Items.Count] 

With This：

playerList.Items[oldCount]