.ToString错误（vb.net）

Question

For some reason, this is not working for me , and I'm not sure. I'm trying to make a Set Home Page button for my webbrowser, and this is the code to check if a page is set, and then goto the page:

    Dim HomepageInfo As String
    If IO.File.Exists(Environment.SpecialFolder.ApplicationData & "\Homepage.Info") = True Then
        HomepageInfo = IO.File.ReadAllText(Environment.SpecialFolder.ApplicationData & "\Homepage.Info")
        WebBrowser1.Url = HomepageInfo.ToString
    Else
        'Create a File with a Default Homepage (www.google.com)
        IO.File.WriteAllText(Environment.SpecialFolder.ApplicationData & "\Homepage.Info", "www.google.com")
    End If

And this is showing as an error: HomepageInfo.ToString, and the error is: "Value of type 'String' cannot be converted to 'System.Uri'."

Thanks for any help!

Answer 1

WebBrowser.Url property accepts an uri object not a string:

Property Value Type: System.Uri A Uri representing the URL of the current document.

So you have to use an instance of Uri class:

Provides an object representation of a uniform resource identifier (URI) and easy access to the parts of the URI.

Code:

Dim HomepageInfo As String
If IO.File.Exists(Environment.SpecialFolder.ApplicationData & "\Homepage.Info") = True Then
    HomepageInfo = IO.File.ReadAllText(Environment.SpecialFolder.ApplicationData & "\Homepage.Info")
    WebBrowser1.Url = New Uri(HomepageInfo.ToString)
Else
    'Create a File with a Default Homepage (www.google.com)
    IO.File.WriteAllText(Environment.SpecialFolder.ApplicationData & "\Homepage.Info", "www.google.com")
End If

Answer 2

尝试像这样使用

WebBrowser1.Url = new Uri(HomepageInfo.ToString);

Answer 3

Quite simple: Your WebBrowser1.Url is not a string, but an URL - an URL is NOT a string, but behaves idfferently, eg options for checking he validity of an URL.

You can construct a new URL to circumvent this problem: WebBrowser1.Url = new Uri(HomepageInfo.ToString)

But this might fail, of the given string is not a valid URL.