I have loaded datatable to listview.Now when i try to do a selected index and retrieve data to display in respective text box. I find some error "input string format incorrect".
but when i directly load from folder it works fine.
When i try to trace the error ---
Data that retrieved from Datatable.Im not able to find the index of the row.
But from folder and listed in ListView.Index value is found.
So far:
Dim breakfast As ListView.SelectedListViewItemCollection = Me.LOV.SelectedItems
For Each item1 In breakfast
index += Double.Parse(item1.SubItems(1).Text)
Next
"Input string format incorrect" means that the Double.Parse() Method throws an exception: The given string (item1.SubItems(1).Text) is not a valid number and cannot be casted into a double.
Use Double.TryParse to avoid an exception here.
From this post it seems below will be your answer
Private Sub listView_ItemCreated(sender As Object, e As ListViewItemEventArgs)
' exit if we have already selected an item; This is mainly helpful for
' postbacks, and will also serve to stop processing once we've found our
' key; Optionally we could remove the ItemCreated event from the ListView
' here instead of just returning.
If listView.SelectedIndex > -1 Then
Return
End If
Dim item As ListViewDataItem = TryCast(e.Item, ListViewDataItem)
' check to see if the item is the one we want to select (arbitrary) just return true if you want it selected
If DoSelectDataItem(item) = True Then
' setting the SelectedIndex is all we really need to do unless
' we want to change the template the item will use to render;
listView.SelectedIndex = item.DisplayIndex
If listView.SelectedItemTemplate IsNot Nothing Then
' Unfortunately ListView has already a selected a template to use;
' so clear that out
e.Item.Controls.Clear()
' intantiate the SelectedItemTemplate in our item;
' ListView will DataBind it for us later after ItemCreated has finished!
listView.SelectedItemTemplate.InstantiateIn(e.Item)
End If
End If
End Sub
Private Function DoSelectDataItem(item As ListViewDataItem) As Boolean
Return item.DisplayIndex = 0
' selects the first item in the list (this is just an example after all; keeping it simple :D )
End Function
Related
I am trying to get the selected text in a ListBox to show in a list box.
I have a button that when I click, will show the text of a Selected item in a ListBox.
I've already tried getting the list box to show the text in a textbox using Listbox.SelectedItem:
Listbox1.SelectedItem = Textbox1.Text
When I do this, I get the error:
System.NullReferenceException: 'Object variable or With block variable
not set.'
Your description is somewhat upside-down.
It's not clear whether you want to set a ListBox.SelectedItem using the Text of a TextBox or you want to set a TextBox.Text with the text of the SelectedItem of a ListBox.
The code says one thing, the description another. The error you have is probably caused by a null SelectedItem (you haven't selected anything).
But, if you want to set a TextBox.Text with the ListBox.SelectedItem text, you can use the GetItemText() method. This method has a plus, it won't raise an exception if the Listbox has no selected Items (the SelectedItem is null (nothing)).
TextBox1.Text = ListBox1.GetItemText(ListBox1.SelectedItem)
The opposite:
You can use the ListBox FindString() and FindStringExact() methods to locate an item in the control's collection corresponding to a given string.
The former finds the first items in the ListBox that starts with the specified string, the latter matches only the whole string.
The search can begin from a specific index. It's not case sensitive.
listBox1.SelectedIndex = listBox1.FindString(textBox1.Text, 0)
' or
listBox1.SelectedIndex = listBox1.FindStringExact(textBox1.Text, 0)
You can continue the search specifying, as the starting point, the index of the item previously found:
private int lboxSearchIndex = -1;
Private Sub ButtonSearch_Click(sender As Object, e As EventArgs) Handles ButtonSearch.Click
lboxSearchIndex = listBox1.FindString(textBox1.Text, lboxSearchIndex)
listBox1.SelectedIndex = lboxSearchIndex
End Sub
Setting the SelectedItem is like using the FindStringExact() method.
Only a full match will set the item, but it's case sensitive.
Listbox1.Text=textbox1.text
Let me know its help you
I'm working on a project that requires I iterate through a list of controls on a tabpage to find all of the checkboxes. Then depending on the state of the box (checked or unchecked) select individual variables (filenames) to then perform either a batch rename or delete of files on the filesystem (cb.checked = perform action).
I have managed to create the "for each" for the iteration of the controls (thanks google) but I'm struggling to figure out how to pick the variables. They are all named differently, obviously, as are the checkboxes. Also the checkboxes are statically assigned to the form/tabpage. Here's what I have at the moment.
Public Sub delBut_code(ByRef fname As String)
If (Sanity = 1) Then
For Each cb As Control In Form1.Controls
If TypeOf cb Is CheckBox AndAlso DirectCast(cb,
CheckBox).Checked Then
If My.Computer.FileSystem.FileExists(fname) Then
My.Computer.FileSystem.DeleteFile(fname)
End If
End If
Next
MessageBox.Show("All Actions Completed Successfully")
Else
MessageBox.Show("Please select a File To Delete")
End If
End Sub
and here is an example of some of the variables:
Dim castle As String = selPath & "\zm_castle_loadingmovie.txt"
Dim factory As String = selPath &
"\zm_factory_load_factoryloadingmovie.txt"
Dim island As String = selPath & "\zm_island_loadingmovie.txt"
N.B selpath collects a user entered folder path and can be ignored here
I would really appreciate any pointers.
First, you can do much better with the loop:
Public Sub delBut_code(ByRef fname As String)
If Sanity <> 1 Then
MessageBox.Show("Please select a File To Delete")
Exit Sub
End If
Dim checked = Form1.Controls.OfType(Of CheckBox)().Where(Function(c) c.Checked)
For Each box As CheckBox in checked
Try
'A file not existing is only one reason among many this could fail,
' so it needs to be in a Try/Catch block.
' And once you're using a Try/Catch block anyway,
' the FileExists() check becomes a slow and unnecessary extra trip to the disk.
My.Computer.FileSystem.DeleteFile(fname)
Catch
'Do something here to let the user know it failed for this file
End Try
Next
MessageBox.Show("All Actions Completed")
End Sub
But now you need to know how have the right value in that fname variable. There's not enough information in the question for us to fully answer this, but we can give some suggestions. There a number of ways you could do this:
Set the Tag property in the Checkboxes when you build the string variables. Then fname becomes DirectCast(box.Tag, String).
Inherit a custom control from CheckBox to use instead of a normal Checkbox that has an additional String property for the file name. Set this property when you build the string variables.
Name your string variables in a way that you can derive the string variable name from the CheckBox variable name, and then use a Switch to pick the right string variable from each box.Name.
Keep a Dictionary(Of CheckBox, String) that maps the Checkboxes to the right string values.
But without knowing more context of the application, I hesitate to recommend any of these over the others as best for your situation.
I'm trying to assign text from "comp" in the form "home" to a textbox with the name "d1" in the form "home".
but this needs to be done with a counter in the form "home".
The code is in a module.
What I've tried=
home.controls("d" & home.counter).text = home.comp.text
I keep getting an error:
use the new keyword to create an object instance ==> the textbox exists in the form
check to determine if the object is null before calling the method ==> the textbox is empty
get general help for this exception
You could use Controls.Find:
Dim controls = home.Controls.Find("d" & home.counter, True)
If controls.Length > 0 Then
Dim txt = TryCast(controls(0), TextBoxBase)
If txt IsNot Nothing Then
txt.Text = home.comp.text
End If
End If
However, normally i would not use this approach since it's error-prone. Why don't you provide a public property in the Home-form that you can access? This property would get/set the TextBox' Text.
For example:
Public Property HomeCompText As String
Get
Return txtHomeComp.Text
End Get
Set(value As String)
txtHomeComp.Text = value
End Set
End Property
Now you can use this clear, safe and maintainable code:
home.HomeCompText = home.comp.text
You could even change the underlying control.
Please, can anyone help me with this problem:
I have a name(s) of control(s) in string format (str) and I want to set property (in code) of that controls using that string-name.
I try something like this but it doesn't work. Actually, I have a problem with expression. When I put exactly the name it works but when i use variable in string format it doesn't.
Dim str as String
str="k3"
Dim g As Image = CType(str, Image)
g.Source = New BitmapImage(New Uri("/APP;component/Icons/hero.png", UriKind.Relative))
This works:
Dim g As Image = CType(k3, Image)
While this does not:
Dim g As Image = CType(str, Image)
I think I understand what you are trying to do, to declare an object by a string...
Essentially for this to work you will need a custom function that returns the Object Type that you are seeking...
You will need to loop through each control and check the name of the control as a comparison, e.g. If oControl.Name.ToString = sString then Return oControl
Example
' A function to return a Control by the Control's name...
Public Function GetControlByName(ByVal oForm As Form, ByVal sName As String) As Control
Dim cReturn As New Control
Dim ctrl As Control
For Each ctrl In oForm.Controls
cReturn = ctrl
If ctrl.Name.ToString = sName Then
Return ctrl ' this is what we want!
End If
Next
Return cReturn
End Function
' Example Usage
Dim oButton As Button = GetControlByName(Me, "Button44")
If oButton.Name.ToString = "Button44" Then
MessageBox.Show("I have found your Button!")
Else
MessageBox.Show("Your button was NOT Found!")
End If
Obviously there is room for error with this function, because if sName is NOT found, then it will return the last ctrl found, therefore, you will need to ensure that the control you seek is indeed found, via the If statement as provided in the example above...
Furthermore, it may not loop through controls inside of containers, menus, etc, but I'm not sure on that, so you will need to check to ensure it's not having that problem...
(The Me in the statement will most likely be used more often than not, though Me could be the name of the form you are searching if you are running the code outside of the form you are searching the form with the function.)
FINALLY, to answer your question, you will need to change Control to Image, and Set CReturn as a New Image, and then use Return ctrl.BackgroundImage (etc) to return the image..
I have two comboboxes. The data sorce of combobox1 is a list of string that is fixed. Combobox2's data sorce will be a list of string that depends on the selection of combobox1. This is very similar to a common case as follows: first enter your contry, then depending on your enter, the second combobox will show you the list of universities in the country.
'Change selection of first combobox
Private Sub cbxClient_SelectedIndexChanged(sender As Object, e As EventArgs) Handles cbxClient.SelectedIndexChanged
Try
If cbxClient.SelectedIndex <> -1 Then
GetAccount()
End If
Catch
Throw
End Try
End Sub
'Based on selection of first combobox, update the data sorce of second combobox
Private Sub GetAccount()
Try
m_listAccount.Clear()
Dim strClient As String = cbxClient.SelectedItem.ToString
For i As Integer = 0 To m_listDS.Count - 1
If m_listDS(i).Client.Tostring = strClient Then
m_ds = m_listDS(i)
Exit For
End If
Next
If Not m_ds Is Nothing Then
For Each row As DataRow In m_ds.Tables("Account").Rows
m_listAccount.Add(row("account").ToString)
Next
End If
cbxAccount.DataSource = m_listAccount
Catch ex As Exception
End Try
End Sub
My problem is that though m_listAccount updates (has the correct information), the choices shown in cbxAccount are not updated according to m_listAccount (has the wrong information). I do not understand why this happens.
Note: Assume that old string in m_listAccount is {"old1"} (the list only has 1 string) and after updating, the string in m_listAccount is {"new"}. Through break points, I get the following:
cbxAccount.DataSorce={"new"}
cbxAccount.SelectedItem={"old1"}
In the form, cbxAccount shows "old1" string.
Try this,
cbxAccount.DataSource = Nothing
cbxAccount.DataSource = m_listAccount
If you are just updating the same list object, the datasource might not automatically update, but should if the pointer changes to the datasource.
Or you could try,
m_listAccount.AcceptChanges()
If m_listAccount is a DataTable
Doesn't look like you're actually calling the databind method, i.e.
cbxAccount.DataBind()
Try putting that just after you set the data source.