I'm writing a program to be used by my library as a step by step checklist when adding new materials (books) to the collection.
Option Explicit On
Option Strict On
Public Class frmCircCounter
Public ReadOnly Property Items As CheckedListBox.ObjectCollection
'confirms all boxes have been checked, and clears them
Private Sub btnClear_Click(sender As Object, e As EventArgs) Handles btnClear.Click
'If
' End If
End Sub
Private Sub CheckedListBox4_SelectedIndexChanged(sender As Object, e As EventArgs) Handles CheckedListBox4.SelectedIndexChanged
'I'm not sure what this is for the internet told me to add this?
InitializeComponent()
'establishes the arrary displayed in the checklistbox
Dim strProperPackage() As String = {"Call Number and Authors Last name?", "Sub-Category Sticker?", "Plastic Wrapping on the Cover if needed?"}
'displays it... or it should!!!?
clbProperPackage.Items.AddRange(strProperPackage)
End Sub
End Class
I expect to have the array displayed in the CLB upon execution
Try looping through your array and add each item into it.
For Each item As String In strProperPackage
clbProperPackage.Items.Add(item)
Next
Your script will not execute the correct way because your using selected index changed but this will only run when a item has been selected in the list.
The best way to test this is by creating a new button and assigning this code to that button. With the button, the script will execute on click.
Public sub btnAccept (sender as object, e and eventargs) handles btnAccept.click
Dim strProperPackage() As String = {"Call Number and Authors Last name?", "Sub-Category Sticker?", "Plastic Wrapping on the Cover if needed?"}
'displays it... or it should!!!? clbProperPackage.Items.AddRange(strProperPackage)
End Sub
Related
I wrote a code to demonstrate the issue:
Public Class Form1
Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
doSomething()
End Sub
Dim controlArr() As Object = {NumericUpDown1, NumericUpDown2, NumericUpDown3, NumericUpDown4, CheckBox1, CheckBox2, CheckBox3, CheckBox4}
Private Sub doSomething()
Dim testStr As String = ""
For Each control In controlArr
Select Case control.GetType
Case GetType(NumericUpDown)
control.value = 1
Case GetType(CheckBox)
control.checked = True
End Select
Next
End Sub
End Class
When I run the code I receive Null Referenece Exception "Object reference not set to an instance of an object", the error disapears when I declare the controlArr array inside DoSomething subroutine. Anyway I would prefer having it declared outside since I am using it in many functions. I would like to understand it better so if you provided me with a topic I could read up on I would be very grateful. Thank you very much for your help.
The issue is that declarations are processed before the constructor. That means that this line:
Dim controlArr() As Object = {NumericUpDown1, NumericUpDown2, NumericUpDown3, NumericUpDown4, CheckBox1, CheckBox2, CheckBox3, CheckBox4}
is executed before the code that creates all the controls on the form and assigns them to those fields. As such, all the fields are Nothing at the time that code is executed and so your array contains a whole lotta nothin'. There's no issue creating objects to initialise fields like that and that code does successfully create an array. It's just that you are implicitly setting every element of that array to Nothing so that's what you get to use later on.
If you want to reference any control then you have to wait until after the form's controls are created. That means, at the earliest, after the call to InitializeComponent in the constructor. More generally, you should do it in the Load event handler, e.g.
Dim controlArr As Object()
Private Sub Form1_Load(sender As Object, e As EventArgs) Handles Form1.Load
controlArr = {NumericUpDown1, NumericUpDown2, NumericUpDown3, NumericUpDown4, CheckBox1, CheckBox2, CheckBox3, CheckBox4}
End Sub
I'm developing a WPF application for my company, and everything needs to look the same way corresponding to our company's look. Therefore I have to make a custom folder explorer, which will feature a treeview of the current directory.
In order to make it easier, I've made the following class, which is basically a TreeViewItem that stores a DirectoryInfo and automaticely browses subfolders when expanded (not to browse everything at once and make the software faster). Here is my code :
Private Class TreeViewPlus
Inherits TreeViewItem
Public dir As IO.DirectoryInfo
Public Sub New()
End Sub
Public Sub New(dir As DirectoryInfo)
Me.dir = dir
Try
If Not dir.EnumerateDirectories Is Nothing Then 'If there are subdirectories, I add an empty item to enable the expansion
Me.Items.Add(New TreeViewPlus)
End If
Catch ex As Exception
End Try
End Sub
Private Sub TreeViewPlus_Expanded(sender As Object, e As RoutedEventArgs) Handles Me.Expanded
Me.Items.Clear()
Try
For Each folder In dir.EnumerateDirectories()
Dim item As TreeViewPlus = New TreeViewPlus(folder)
item.Name = Text.RegularExpressions.Regex.Replace(folder.FullName, "[^a-zA-Z0-9]", "")
item.Header = folder.Name
Me.Items.Add(item)
Next
Catch ex As Exception
End Try
End Sub
End Class
And here is the code where I initialize the first directories: (TRV_Arbre is the name of my TreeView)
Sub New()
...
For Each Drive As IO.DriveInfo In IO.DriveInfo.GetDrives
Dim item As TreeViewPlus = New TreeViewPlus(Drive.RootDirectory)
item.Header = Drive.Name
TRV_Arbre.Items.Add(item)
Next
...
End Sub
The Issue I've got is that the first level of items correctly expand, but not the following ones.
See here : https://youtu.be/E6BJbKal5Sk
I've already debugged my code a little, and it correctly creates the different Items.
Can anyone help me for this ? Thanks in advance.
There is a simple way to solve this problem and that is to Override the OnExpanded Sub on the Base TreeViewItem class instead of implementing your own Expanded method. Then in the end you execute MyBase.OnExpanded(e) method which seems to contain the correct update events to send out to whomever listens. In this case your TreeView.
Protected Overrides Sub OnExpanded(e As RoutedEventArgs)
Me.Items.Clear()
Try
For Each folder In dir.EnumerateDirectories()
Dim item As TreeViewPlus = New TreeViewPlus(folder)
item.Name = Text.RegularExpressions.Regex.Replace(folder.FullName, "[^a-zA-Z0-9]", "")
item.Header = folder.Name
Me.Items.Add(item)
Next
Catch ex As Exception
End Try
MyBase.OnExpanded(e)
End Sub
I have been looking for the specified code all day long, browsing through the MSDN libraries from microsoft, but I wasn't able to find or come up with a solution:
Question: How can I add a string to an existing array?
I have been trying this
Dim Items() As String
Items = ListBox1.Items.Cast(Of String).ToArray
Array.Reverse(Items)
Me.ListBox1.Items.Clear()
Me.ListBox1.DataSource = Items
**Items.add("Add This to my array")**
But this doesn't work unfortunately.
My code is loading a populated listbox into an array (reverses the entries, and then cleans the listbox before populating it with the array).
How can I add to this array now?
Try this.....
Public Class Form1
Private Sub Form1_Load(sender As Object, e As EventArgs) Handles MyBase.Load
Dim Items As List(Of String)
Items = ListBox1.Items.Cast(Of String).ToList
Items.Reverse()
Items.Add("Add This to my array")
Me.ListBox1.Items.Clear()
Me.ListBox1.DataSource = Items
End Sub
End Class
almost identical code (slightly rearranged), using a List instead of an array
I have attached code for reference. I am trying to create database for my project details. I have currently 2 forms:
main form
project detail form
Main form used to switch various forms
Project detail forms are meant for add / edit / load project details
My main form in visual basic look like this.
Public Class Form1
Private Sub Form1_Load(sender As Object, e As EventArgs) Handles MyBase.Load
End Sub
Private Sub Bt_Project_Details_Click(sender As Object, e As EventArgs) Handles Bt_Project_Details.Click
Me.Hide()
Project_Details_Form.Show()
End Sub
End Class
My project detail form look like this.
Public Class Project_Details_Form
Private Sub Project_Details_Form_Load(sender As Object, e As EventArgs) Handles MyBase.Load
'TODO: This line of code loads data into the 'Project_Data_Set.Project_Data_Table' table. You can move, or remove it, as needed.
Me.Project_Data_TableTableAdapter.Fill(Me.Project_Data_Set.Project_Data_Table)
End Sub
Private Sub Bt_Load_Project_Click(sender As Object, e As EventArgs) Handles Bt_Load_Project.Click
End Sub
Private Sub Bt_Cancel_Click(sender As Object, e As EventArgs) Handles Bt_Cancel.Click
Me.Hide()
Form1.Show()
End Sub
Private Sub BindingNavigatorAddNewItem_Click(sender As Object, e As EventArgs) Handles BindingNavigatorAddNewItem.Click
Project_Data_TableBindingSource.AddNew()
End Sub
Private Sub Project_Data_TableBindingNavigatorSaveItem_Click(sender As Object, e As EventArgs) Handles Project_Data_TableBindingNavigatorSaveItem.Click
Me.Validate()
Me.Project_Data_TableBindingSource.EndEdit()
Me.TableAdapterManager.UpdateAll(Me.Project_Data_Set)
End Sub
Private Sub BindingNavigatorDeleteItem_Click(sender As Object, e As EventArgs) Handles BindingNavigatorDeleteItem.Click
Project_Data_TableBindingSource.RemoveCurrent()
End Sub
Private Sub FillByToolStripButton_Click(sender As Object, e As EventArgs)
Try
Me.Project_Data_TableTableAdapter.FillBy(Me.Project_Data_Set.Project_Data_Table)
Catch ex As System.Exception
System.Windows.Forms.MessageBox.Show(ex.Message)
End Try
End Sub
End Class
Now I am facing a few problems:
Whenever I run the program, try to enter first entry data being saved but with empty value. The data enter next time being stored properly. How can make my first entry visible?
In below code:
Private Sub BindingNavigatorAddNewItem_Click(sender As Object, e As EventArgs) Handles BindingNavigatorAddNewItem.Click
Project_Data_TableBindingSource.AddNew()
End Sub
I am using AddNew(). This working fine, but problem is even I don't enter data like date, name kept empty, data recorded in their position is store empty only. I would like to say if any of project data set is empty give error message (since it mandatory for user to enter those data)
Is there any other method where i can assign value individually .
Like my Project database contain project name, customer name etc. if i say new button pressed clear all field. Once form filled individual value being record once save button pressed
Private Sub BindingNavigatorAddNewItem_Click(sender As Object, e As EventArgs) Handles BindingNavigatorAddNewItem.Click
Project_Data_TableBindingSource.AddNew()
End Sub
im just wondering on how can i pass value of a variable to another form from a different form
I have a form called frmSearch then I have another form called frmMain from frmSearch i have a varible A which is publicly declared and i wanted the value of A to frmMain i've tried the following
frmMain
dim B = frmSearch.A
but everytime i checked the value of B it always returns a blank string
also when i checked the value of frmSearch.A it also returns nothing even though it returns a value when i checked it in frmSearch
please help im really stuck
thanks in advance
Accessing a field of a form shouldn't be a problem. Just make sure that at the time you are reading the field it is already assigned.
Public Class Form1
Private Sub Button1_Click(sender As System.Object, e As System.EventArgs) Handles Button1.Click
Dim form = New Form2
Debug.Assert(form.A Is Nothing)
form.ShowDialog()
Debug.WriteLine(form.A(0))
End Sub
End Class
Public Class Form2
Public A As String()
Private Sub Form2_Load(sender As System.Object, e As System.EventArgs) Handles MyBase.Load
A = {"abc", "aaa"}
End Sub
End Class