How can I empty a collection in .NET? Let me specify that I don't want to destroy the collection , I just don't want it to have the objects it had before (so I can refill it from scratch) .
View 3 Repliesthe vars outside the procedure
Dim rentalRecords As New ArrayList() ' The arraylist containing the records
Dim carRecords As New ArrayList()
Dim currentRecordIndex As Integer ' The index of the current record
[code]....
How can i check if a string collection is empty? I tried
VB.NET
My.Settings.IPBank.Count = 0
But it said
Quote:
Object reference not set to an instance of an object.
I have a list of user names (we'll call 'original list') one object is returning. I have a list of user names (we'll call 'filtration list') another object is returning. I am testing a method that returns all of the items from the original list not in the filtration list. Ideally what I want is something like:
Assert.That(returnedList, Has.No.Members.In(filtrationList))
So far the only thing I can do is iterate over the filtrationList and do
Assert.That(returnedList, Has.None.EqualTo(filteredUser))
treeView control which has been plaguing me for the last few days.
I'm not exactly sure what is causing this problem to arise, so I will just explain what my program is trying to do.
I am building an application which will have plugin support. I have created a Plugin interface, which is implemented by each plugin, as well as a host interface, which is implemented only by the host application.
Each plugin has an Action subroutine, and when finished, it is supposed to call the ExecutionComplete subroutine in the host interface.
Now, onto the problem. I have a treeView on the host form, which has several nodes in it. If I create a button on the form which displays a message box with treeView.nodes.count, it shows up fine, and everything works as expected. If I attempt to display the same messagebox from the ExecutionComplete subroutine, it also gives the correct number of nodes.
This is where things get a little weird. I have implemented a save feature into my program, so you can save and load data. For some weird reason, if you have loaded the data from a file, rather than adding each node manually, it now returns an empty node collection ONLY if I try to access it from ExecutionComplete. If I try to access the nodes from a button, it still returns the correct values!
What could it possibly be about the ExecutionComplete subroutine that makes it return a value any different than what is returned when the exact same code is placed in a button click event? And why does it only happen when I've loaded the data from a file? I just don't understand how loading it from a file is any different than them adding the nodes manually. The nodes are definitely being added, as I can see them, and the button click event can also see them. Also, ExecutionComplete is obviously able to read the contents of the treeView, because it works just fine if the user has set up the treeView manually.
I'm trying to get images to display in a WPF ListView styled like a WrapPanel as described in this old ATC Avalon Team article: How to Create a Custom View. When I try to populate the ListView with a LINQ-to-Entities queried collection of ADO.NET Entity Framework objects I get the following exception:
[Code]...
Is it good practice to store sub-collections of item X inside a parent collection of item X for caching 'filter-queries' which are performed on the parent collection? (They won't be used together (as in color AND type).) Or is it also ok to just Loop over the collection and return the correct entities in a temporary collection?
[Code]...
I have the following classes:
Product, Service and OrderItem
Product and Service must inherit OrderItem. So basically I want to store OrderItem object in my shopping cart and these object are store in a list.
Public MustInherit Class OrderItem
Private m_enuItemType As TypeOfItem = TypeOfItem.None
Private m_strUserID As Integer[code].....
I have been researching for a couple of days now and to no avail. Does Anyone know how to make a custom collection that take advantage of the collection editor? I would like to be able to have 3 Color Values, 1 Boolean and 1 String.
View 15 RepliesIm making a program that reads from an ini file and then prints it in the form I have a problem when Im trying to open the compiled file the form is just blanc and there isnt any text its like it isnt reading from my code
here is the code
Imports System
Imports System.Collections
Imports Microsoft.Win32
Imports icsharpcode.sharpziplib.zip
[code]....
is there a way to show in datagrid only those row that has column that is empty, im using this code
Me.DataGridView1.DataSource = ds.Tables("0").Copy() but it shows all the data from my table.
What is the best datagridview event to use these codes I want to check column 0 is empty or has some value
If e.ColumnIndex = 0 Then
If DataGridView1.CurrentCell.Value = "" Then
MsgBox("Empty Value")
[code]....
How can i hide a picturebox if it contains NOTHING
Dim a As Integer
Dim PicString(26) As Image
Dim PicBox() As PictureBox = {Box1, Box2, Box3, Box4, Box5, Box6, Box7, Box8, Box9, Box10, Box11, Box12, Box13, Box14, Box15, Box16, Box17, Box18, Box19, Box20, Box21, Box22, Box23, Box24, Box25, Box26}
[code]....
This does not work... The PicBox(c) = Nothing ... is not a valid command.
My app is functionally fine. Although, after the login, it throws up this error:
"Argument 'Path' is Nothing or empty". If I click continue, it proceeds without any problem. I looked up on msdn forums and realized that I need to add a valid argument 'path'. Here is the link to the msdn page I looked at:
[URL]
ive been searching round the net but the only examples i can find are for vb6 which i know nothing about, i want to be able to scan a folder and all sub folders with in it and delete any folders which are empty.
This is all the code ive put together so far:
vb Dim folder2scan as string = Folderbrowser.selectedpath
If IO.Directory.GetFileSystemEntries(folder2scan).Length = 0 Then
End If
Im making a program that reads from an ini file and then prints it in the form I have a problem when Im trying to open the compiled file the form is just blanc and there isnt any text its like it isnt reading from my code
here is the code
Imports System
Imports System.Collections
Imports Microsoft.Win32
[Code]....
I am trying to empty my input buffer when I open up the serial port using this code but its not working any suggestions? Mainly just look at the last line [code]
View 6 RepliesI am using VS 2008 to upload a zip file created earlier in the program, the ZIP file is created where expected on the FTP server but it is empty
View 2 RepliesWhen listbox is added to by the user a number of empty RTF files are created and saved with a string variable SavePath1,SavePath2 and SavePath3. The user can then add date to 3RichText boxes and save the data. The data can then be cleared from the RichText boxes, anotheraddition to the listbox and fill the RTB and save. I need to trap the RTBs being filled and the clear button being pressed before the data is saved. To do this I need to test for empty files and tell the user the data has not yet been saved.
View 1 RepliesIm trying to create an empty element in an xml file but still want to be able to close other elements without changing the empty element.What XMLTextWrite does to empty elements:
<Data>
<Feed>
<EmptyElement />
</Feed>
<Data>
When i use the text writer i cant use <writer>.StartEndElement() it starts to screw with my empty element. When im still having my program write inside feed. Here some code your you to drool over.
My example
Dim Settings As New XmlWriterSettings()
Settings.Indent = True
[code]....
I'm trying to add a progressBar to my form but it always shows full or empty, it never shows anything in between like 20%, 30% etc. Here is my
ProgressBar1.Minimum = 0
ProgressBar1.Maximum = 2
ProgressBar1.Step = 1
[code].....
I am currently writing an application, where the user clicks a button, it scans for empty folders and then puts them in a listbox.The user can then then select the folders in the listbox and click delete. how to i get the scan button to find the empty folders?
View 6 RepliesI'm trying to understand why my print preview is not showing the contents of the file (I've double checked that the file is in the correct directory and is not empty)
Imports System.IO
Imports System.Drawing.Printing
Public Class Form1
[Code].....
I've been searching around a lot to figure this out. I found some code that sort of works:
VB.NET
If String.IsNullOrEmpty(CStr(Me.dgvList.Rows(i).Cells(0).Value)) Then
End If
[code].....
Empty values in byte array at the end of one packet are replaced by beginning values of the next packet sent in TCP connection. How may I avoid this?
View 4 Repliesive been searching the whols google, and i couldnt find a ny solution.. i was wondering if someone here can help me out, i am loading a listbox items from a .txt files, and sometimes there are empty lines, there is a way i can delete them?
View 10 RepliesI'm trying to add a service company from a vb form to an SQL table. It works as long as I enter something in every field on the form. If not I get a syntax error so I thought I should check that the field values were not null
I've tried to add a sub to check for blanks but it's not working
btw the table will allow nulls for all fields
Private Sub btnSubmit_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnSubmit.Click
Try
[Code].....
I have a DataGridView that has some columns with dates. It binds to an in-memory Datatable which gets loaded from an string array of data passed back from the backend Some of the rows returned have nulls for the date columns. Solution 1: If I define the Date column in the DataTable as "string" I can easily convert those nulls to empty strings and display it in the grid as empty strings (desired results). However, if the user clicks on the date column header to sort by date, it doesn't order the rows as you want. You get a purely string sort order. Not acceptable
[Code]...
I'm trying to support Basic.NET on my framework so I'm trying to convert C# 4 code to Basic.NET 10. Microsoft is committed to "co-evolve" these two but I'm having a problem with collection initialization... I found that I can initialize a collection much like in C#:
[Code]...
I've got the following ADO.NET Entity Framework Entity Data Model:I want to find all the Policyholders with both a Service of a given Id and also a Keyword of a given Status.
This LINQ Does Not Work:
Dim ServicesId As Integer = ...
Dim KeywordStatus As Integer = ...
Dim FoundPolicyholders = From p As Policyholder In db.PolicyholderSet.Include("Keywords").Include("Services") _
Where p.Services.Id = ServicesId _
And p.Keywords.Status = KeywordStatus _
Select p
The Where clause cannot search the p.Services and p.Keywords EntityCollections in that way.
[Code]...