Adding And Removing Items From The List And Tree Views
Mar 10, 2009
I am trying to learn how to work with the different controls in Visual Studio for VB.Net in particular the List View and Tree Views. I don't have any code to show as I am not working on anything in particular just messing around with it to learn what the different controls do that weren't covered in my Intro to VB.Net class last semester.I would like a clearer explanation on how to actually use code for these controls. In particular adding and removing items from the List and Tree Views using code.
I have used list views for a project. I have used sum items on the items. The sub items are prices of products. I will need to use these sub items to come up with a total.Also, i have used to listviews, for a smoother look and feel. You click the product which then is removed from the list view and added to the second one. Would this also "move" the sub item across to the other list view?
i'm creating a web form and i want a user to be able to make certain selections and then add the selections to a text box or listbox.Basically i want them to be able to type someone name in a text box ... check some check boxes and for it up date either a text for or a list box with the result on button click...
I have button that adds items to a list box and a button that removes it...the one that adds it works great but when i select an item to remove it doesn't remove it..i don't know if there's something wrong with the code or not..
Private Sub btn_Remove_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btn_Remove.Click list_MyOrder.Items.RemoveAt(list_MyOrder.SelectedIndex) prices(list_MyOrder.SelectedIndex) = 0 MsgBox("Select any item to remove") End Sub
I have a generic list that I'm removing items out of using List.Remove(Object). I have been removing items but whenever I get to the fifth item I'm removing it fails and does not remove it from the list. It doesn't seem to matter what I'm removing but everytime I try to remove five items it fails on the fifth item.
If I have 3 times selected and when I click "submit" for example I want all my selected items to be removed, but when I try to do this only my first selected item is removed.
ListBox.Items.Remove(ListBox.SelectedItems)
How do I remove all 3 items from the list box at the same time?
Public Structure ReportOrderType Public ReportName As String Public ReportDate As Date Public SaveFile As String End Structure [Code] ....
Basically, I have a list of reports. In one place they get ordered, and later on the program looks to see which ones have come back -- see if the .SaveFile exists on disk. If it exists, then that report gets processed, and then I want to remove that item from the list of reports-on-order. However, I get an error message back that by doing the .Remove(R), I've changed the list itself & things won't go well with the rest of the For Each loop, which makes some sense.
When I get to this routine, the list of ordered reports will be something from a couple of dozen or less, and some number of them (perhaps zero, perhaps all, probably a few) will exist & be processed & then should be removed from the list. How should I go about accomplishing this? This is my first time working with List(of t) as a Visual Basic tool; everything I've used in the past has been with arrays, and I can do this there.
The ListBox gets populated correctly. After it is populated, i have a CommandButton and on the click event of the button, i want to remove selected items from the ListBox. So in the click event of the CommandButton, i have written the following code:
lstItems.Items.Remove(lstItems.SelectedItem)
After selecting an item from the ListBox and when i click the CommandButton, i get an error as "Items collection cannot be modified when the DataSource property is set".
I've searched on the Internet and I can't find a solution to this simple problem. I've also looked on Microsoft's MUCH improved MSDN site and haven't found a solution, so here it goes. I'm trying to remove an entry from a list of class and it doesn't get removed. Here's a sample of the code I'm trying: (I renamed the class and variable names to make it a simple example)
Dim lstClass As New List(Of TheClass) Dim mClass As TheClass I tried this first mClass.filename = "The Entry to Delete" lstClass.Remove(mClass)
I've gotten a listbox control to populate with a list of installed fonts, but I need to be able to click a button and remove the selected item from the listbox. How do I do this? Every time I try, an exception is thrown.
Here is the code:
Public Class Form1 Dim fonts as New Drawing.Text.InstalledFontCollection Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
I am using a DataGridView bound to a BindingSource which is itself bound to a List of objects. This all works well until I remove objects from the list. If I am scrolled down to the bottom of the DataGridView and then remove a bunch of items from the list it is bound to it generates a DataError exception because the length changed and the rows I am looking at no longer exist... I changed my code to handle that error, but now instead of popping up a message it SLOWLY erases the data in each of the newly invalid rows at the end of the table (I think each time it does one it generates a new DataError, which is why it is so slow).
How do I prevent this? I want to be able to dynamically (and programmatically) add and remove items from the table without the possibility of this error... I assumed this would be handled automatically as part of the data binding process but I guess not.
I am attempting to read the results from a SQL query into a List(Of) and I can see the List.count while adding items to the List increments, however in another part of my code when I am attempting to read the List the List.Count returns 0. My List is as follows:
In VS 2008, VB.Net, I am successful connecting to a local SQL Server (version 8) and seeing all tables/views/procedures in Server Explorer. The local OS is Win XP Pro SP3. I created an ODBC data source to a remote SQL server (also version 8) with a database of the same structure as the local one. The connection tests out ok. The remote computer runs Windows Server 2000 SP4. In the VS 2008 Server Explorer I add this ODBC source. When I click on the plus-signs to expand items, neither the tables nor the views show anything, whereas the full list of procedures appears. Is it the old SQL Server version? Is it the old Server OS version? Something else alltogether?
This is what I'm sure will be the first of many noob-ish questions from yours truly... I'm studying as a mature student for a Computing Degree (encompassing web design, hardware, programming and systems analysis). The programming seems to be my weak spot this year. I enjoyed C++ last year, doing basic console applications, but progamming visually with VB in Visual Studio 2008 I'm struggling!
In VS 2008, VB.Net, I am successful connecting to a local SQL Server and seeing all tables/views/procedures.I created an ODBC data source to a remote SQL server with a database of the same structure as the local one.The connection tests out ok. In the VS 2008 Server Explorer I add this source. When I click on the plus-signs to expand items, neither the tables nor the views show anything, whereas the full list of procedures appears.How can I see the lists of tables and views in Server Explorer for an ODBC source?
I wish to make a project where a teacher views a list box with a list of students of a class. When he selects a name from the first list box the second listbox would change its data to show the grades for that one student.
Private Sub RemoveCurrentKey(ByVal name As String) Dim key As RegistryKey = Registry.CurrentUser.OpenSubKey("Software\", True) key.DeleteSubKeyTree(name) End Sub
But it simply wont remove the key tree, How do I remove the whole tree?
I'm learning how to add items from a list box to a combo box. I'm trying to follow what's going on in the function loop and comparing a boolean and selected index. I can see that it's comparing the item chosen to each item already in the combo box to make sure that it's not already there. If function finds that it's not in the list it sends back that it is true that the item is not in the list.
It then continues to the statement that adds item to the list. The code for the double click event is working fine and items are getting added to combo box. However, the code for the add button isn't functional. I'm not seeing why it doesn't work? I coded out the original code, and replaced with something I thought might work but it still isn't functional. [Code]
I have some code that adds items to a List(of Object).
Here's my original code
Dim BeaconStoryList as New List(Of My.StoryType) Dim BeaconStory as New My.StoryType Dim NewStories() as New Foriegn.StoryType = GetStories
[Code]....
But as soon as the code assigned "Chicken" to BeaconStory.Title, then BeaconStoryList(0).Title would also change to "Chicken".
With my second version of the code this did not happen.
It's as though it was placing pointers into the elements of the array rather than values. If that is the case, however, then why does my second version of the code work - I'm still passing in the same thing - aren't I?
I'm using the free version on Visual Basic 2008 (through school).The assignment is to populate a list box from user input text. The textbook only talks about populating a list of known items.ex animalListBox.Items.Add("dog") Which works just fine, however, we don't know what the user will input.
I'm still learning VB.net and there is a bit of code I have added which is an array and I want to add a list of items to the array. If that makes sense. I have 6 classes two have arrays.
Here is the code from one of the classes Public Function getItems() As Array Return _LevelItems End Function
How would I add the item list to this? Where do I put it? Like underneath it or in the items class? That code is in the Level class.
I have a small program that talks to a server, grabs the content from a website using a php webscraping program and then places the results in a listbox as a string. My problem is taking this string and creating a list from it. Each item in the string is followed by a | (pipe). I have included the code that I've tried below:
Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click Dim str As String Dim start As Integer = 1
I have this code to return a list of fund sources for our organization.
Dim FundSourceList As New List(Of FundSource) Dim fs As New FundSource If results.Count > 0 Then[code].....
The problem is that when I loop through the resulting FundSourceList all it shows is the last value. For example, if I have three fund sources (state, federal, athletic), then when I use this code to loop through all I get listed is athletic, athletic, athletic.
For Each FundSource In FundSources Debug.Print(FundSource.FundDescription) Next
So I change the code to this. I moved the creation of the fs variable inside the loop.
Dim results = From result In dsResult.Tables(0) Select result Dim FundSourceList As New List(Of FundSource) If results.Count > 0 Then[code]....
This works fine but now I'm creating a new class over and over again. It seems a little inefficient to me. Can I not create the class outside the loop and use it over and over again?
