VB System.NullReferenceException是未處理由用戶代碼

Question

下面是代碼：

Private Sub GeckoWebBrowser1_Navigated(sender As Object, e As Gecko.GeckoNavigatedEventArgs) Handles GeckoWebBrowser1.Navigated 
    ToolStripTextBox1.Text = GeckoWebBrowser1.Url.OriginalString 
    **Parent.Text = GeckoWebBrowser1.Site.Name.ToString** 
    ''GeckoWebBrowser1.DocumentTitle.ToString 
    ''GeckoWebBrowser1.Site.Name.ToString() 
End Sub 

如果我啓動程序VB說我System.NullReferenceException是由粗線用戶代碼未處理。

Answer 1

好吧，我擁有它。我把定時器

Parent.Text = GeckoWebBrowser1.Site.Name.ToString

，因爲應用程序不會得到一個站點名稱前的網站加載

Answer 2

試圖改變你的代碼：

Private Sub GeckoWebBrowser1_Navigated(sender As Object, e As Gecko.GeckoNavigatedEventArgs) Handles GeckoWebBrowser1.Navigated 
    ToolStripTextBox1.Text = GeckoWebBrowser1.Url.OriginalString 
    if GeckoWebBrowser1 isnot nothing AndAlso GeckoWebBrowser1.Site isnot nothing then 
    Parent.Text = GeckoWebBrowser1.Site.Name.ToString 
    ''GeckoWebBrowser1.DocumentTitle.ToString 
    ''GeckoWebBrowser1.Site.Name.ToString() 
    end if 
End Sub