Value of type string cannot be converted to system.uri?

Question

I am building a simple web browser in VB 2013, in Windows 8.1. I used a video on youtube to guide me through the process of creating this browser. 

When my coding was done, I pressed Local Machine and got a build error. The error is located in the area where the code wants the WebView to Navigate to a URL via TextBox.text. The error message I got: The value of type string cannot be converted to system.uri. 

Here is my code:

Private Sub TextBox_TextChanged(sender As Object, e As TextChangedEventArgs) Handles TextBox.TextChanged
        WebView.Navigate(TextBox.Text)

Please, use easy to understand language lol.

Answer 1

Public Class Form1

    Private Sub Button1_Click(sender As System.Object, e As System.EventArgs) Handles Button1.Click
        Dim uriString As String = "ylabnez.xsb/retddg"
        'Dim uriString As String = "http://www.google.com"

        If Uri.IsWellFormedUriString(uriString, UriKind.Absolute) Then
            Dim MyURI As Uri = New Uri(uriString)
            MessageBox.Show("Success converting " & uriString & " to a valid URI", "All is well", MessageBoxButtons.OK, MessageBoxIcon.Information)
        Else
            MessageBox.Show("Cannot convert " & uriString & " to a valid URI", "Error", MessageBoxButtons.OK, MessageBoxIcon.Error)
        End If
    End Sub
End Class

try as is and then comment out the nonsense on and uncomment the google one

Answer 2

The error message I got: The value of type string cannot be converted to system.uri. 

What type of object is WebView?  If it's a WebBrowser object then this is the method you are using. 
http://msdn.microsoft.com/en-us/library/40x214wa(v=vs.110).aspx

A string should be a valid type for the argument for this method - if you are getting an error then perhaps the string that is being passed is not a valid uri.  You can do the conversion explicitly using
        WebView.Navigate(New Uri(TextBox1.Text))

To test if the string can be converted to a valid uri then see here:
http://msdn.microsoft.com/en-us/library/ms131572(v=vs.110).aspx
http://msdn.microsoft.com/en-us/library/system.uri.trycreate(v=vs.110).aspx

Th

Answer 3

Hi,

 I just wanted to add that you can`t do this in the TextBox1.TextChanged event. Every time you type a character in the textbox or remove a character from it then the TextBox1.TextChanged event is triggered and it tries to navigate to the webpage and if you don`t have the URL all typed in then it will give you an error.

For example say i want to go to "www.Google.com". As soon as i type the first "w" it will trigger the TextChanged event and when the WebBrowser tries navigating to "w" it will throw an error.

Also you should name your textbox to something that will identify it like "TextBox_URL" or something so that you can easily tell which textbox is for what.

Answer 4

I am building a simple web browser in VB 2013, in Windows 8.1. I used a video on youtube to guide me through the process of creating this browser. 

When my coding was done, I pressed Local Machine and got a build error. The error is located in the area where the code wants the WebView to Navigate to a URL via TextBox.text. The error message I got: The value of type string cannot be converted to system.uri. 

Here is my code:

Private Sub TextBox_TextChanged(sender As Object, e As TextChangedEventArgs) Handles TextBox.TextChanged
        WebView.Navigate(TextBox.Text)

Please, use easy to understand language lol.

After typing a URL in the TextBox and pressing Enter this code only validates the TextBox contains text before it uses a function to check the URL against your Domain Name Server. If the URL doesn't exist the try/catch statement is necessary as the code "Dim host As IPHostEntry = Dns.GetHostEntry(TBox1Text)" will crash the app because the TextBoxs text is not a valid URL. I didn't spend the time to catch the proper sockets exception but it works good enough for me.

Also in your code I see you are using TextBox which is a a keyword (I think that's what its called) for the control TextBox. You should not use keywords for actual names of controls or anything else. Don't use Form for a Forms name or PictureBox for a PictureBoxs name, etc. Or Dim Integer as Integer or anything like that. Use Form1 or PictureBox1 or TextBox1 or some other names.

Option Strict On

Imports System.Net

Public Class Form1

    Private Sub Form1_Load(sender As Object, e As EventArgs) Handles MyBase.Load
        Me.CenterToScreen()
    End Sub


    Private Sub TextBox1_KeyDown(sender As Object, e As KeyEventArgs) Handles TextBox1.KeyDown
        If e.KeyCode = Keys.Enter Then
            If TextBox1.Text <> "" Then
                If ValidateHostName(TextBox1.Text) = True Then
                    WebBrowser1.Navigate(TextBox1.Text)
                Else
                    MessageBox.Show("TextBox1 contains an invalid URL." & vbCrLf & "Please enter a valid URL in the TextBox and try again.")
                End If
            End If
        End If
    End Sub

    Private Function ValidateHostName(ByRef TBox1Text As String) As Boolean
        Dim Value As Boolean = False
        Try
            Dim host As IPHostEntry = Dns.GetHostEntry(TBox1Text)
            Dim ip As IPAddress() = host.AddressList
            If ip.Count = 0 Then
                Value = False
            Else
                Value = True
            End If
        Catch ex As Exception
        End Try
        Return Value
    End Function

End Class

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Please BEWARE that I have NO EXPERIENCE and NO EXPERTISE and probably onset of DEMENTIA which may affect my answers! Also, I've been told by an expert, that when you post an image it clutters up the thread and mysteriously, over time, the link to the image will somehow become "unstable" or something to that effect. :) I can only surmise that is due to Global Warming of the threads.