Ok, I am trying to pass data from one form to another form using the overload constructor method. I could just use public variables or properties, but would like to use the overload method.
Here is the code section from my first form that calls the second form...
Private Sub dgvAllWO_CellDoubleClick(sender As Object, e As System.Windows.Forms.DataGridViewCellEventArgs) Handles dgvAllWO.CellDoubleClick
Dim I As Integer
I = dgvAllWO.Rows(e.RowIndex).Cells.Item(0).Value
Dim frmWO(I) As New frmWorkOrder
End Sub
Here I have the code from the other form...
Public Class frmWorkOrder
Public Sub New(ByVal ID As Integer)
InitializeComponent()
End Sub
Public Sub New()
InitializeComponent()
End Sub
End Class
After doing that, i now get an error on 'NEW' on this line of code on my first form.
Dim frmWO(I) As New frmWorkOrder
Error 1 Arrays cannot be declared with 'New'
Why is this happening? After overloading the constructor my form class is turned into an array? Im not sure what is happening here. I am grateful for any help or direction you can give me. Thanks in advance.
In VB New is the constructor, so you need to pass the value to the constructor like this:
Dim frmWO As New frmWorkOrder(I)
If frmWO is an array, then something like this:
frmWO(I) = New frmWorkOrder(I)
This line:
Dim frmWO(I) As New frmWorkOrder
should be
Dim frmWO As New frmWorkOrder(I)
Related
I feel comfortable when instantiating a class, then using it within the same function, but now I need to instantiate a class from a toolbar button:
Dim pll As New Polyline()
Debug.WriteLine("TSB_Polyline_Click:: a new polyLine is born : " & pll.Count)
pll.AddPoint(0, 0)
And then I need to run the pll.AddPoint from my class method in another sub:
Public Sub MyEvent(sender as object, e as myEvent) Handles myEvent
Dim x as Double, y as Double
pll.AddPoint(x,y)
There I have my error (System.NullReferenceException: 'Object reference not set to an instance of an object.'), pll = Nothing (no error in my constructor, my class worked from the toolbar button_Click)
I tried to declare pll public and shared:
Public Shared pll As Polyline
And even to import it:
Imports oGIS.Polyline
Nothing works. My Class is instanciated in the first Sub (toolbar button), but somehow dies when leaving the Sub...
Is there any other solution that doing it using VB6 instead of VB.Net ?
I am a bit desesperate, I found no such topic anywhere on Google...
If you need to access a variable in more than one method then it should be declared outside all of them. It should be Private if you don't need to access it outside the type it's declared in and it should only be Shared if you specifically need all instances of the class accessing the same object. In your case, Private and not Shared is the obvious choice:
Private pll As Polyline
You now set that field in the first method and get it in the second.
I am guessing a partial look at your class would be something like this...
Public Class Polyline
Public ReadOnly Property CountOfPoints As Integer
Get
Return ListOfPoints.Count
End Get
End Property
Public Property ListOfPoints As New List(Of Point)
Public Sub AddPoint(x As Integer, y As Integer)
Dim p As New Point(x, y)
ListOfPoints.Add(p)
End Sub
End Class
Declare a class level (in this case the class is a Form) variable which can be seen and used by any method in your form.
Public Class Form1
Private LocalPolyLine As Polyline
'This is a local list, not part of the class
'It is a list of the number of instances of the class you have created
Private ListOfLines As New List(Of Polyline)
Private Sub Button1_Click(sender As Object, e As EventArgs) Handles Button1.Click
'Pretend this is a button on your toolbar used to create a new line
'Each time you click this button you have a completely new line with no points
LocalPolyLine = New Polyline
'If you want to keep track of how many lines you have...
ListOfLines.Add(LocalPolyLine)
End Sub
Private Sub AddPoint(x As Integer, y As Integer)
Debug.Print($"Number of Lines is {ListOfLines.Count}")
Debug.Print($"Number of points on current line {LocalPolyLine.CountOfPoints}")
LocalPolyLine.AddPoint(x, y)
Debug.Print($"Number of points on current line {LocalPolyLine.CountOfPoints}")
End Sub
'To see all the points on the line...
Private Sub ViewPoints()
For Each p In LocalPolyLine.ListOfPoints
Debug.Print($"The coordinates of the point are {p.X},{p.Y}")
Next
End Sub
End Class
I am newbie here. I need your help. I am trying to develop a tool where I want to implement multi-threading in vb.net. I am stuck in a place which I could not resolve. Let me explain you.
I have created a custom class as below:
Public Class TestClass
'Few private Members of my class
Private a As String,b As String
Public Structure abc
Dim xx as object
Dim yy as object
Dim zz as object
End Structure
Public aa(10) As abc
'Now I needed to override the constructor as the initialization of
'instance of this class can be made in two different ways due to
'requirement
Public Sub New(ByVal xy As String,ByRef yz As Object)
'Some internal method to initialize the object
Me.a=xy
Me.b=xy
End Sub
'Another way to create the instance
Public Sub New(ByVal xy As String,ByVal yz As String)
'Some internal method to initialize the object
Me.a=xy
Me.b=yz
End Sub
'Now a public method which I want to call using threading
Public Sub TestSub()
'Do something with Me.a,Me.b and aa(some index)
End Sub
End Class
Now in a different module I am creating the instance of this class as below:
Dim X1 As New TestClass("Some String",<Some Object reference>)
Dim X2 As New TestClass("Some String","Some String")
Now I have declared a sub in the same module like below
Sub DoMyStuff(ByRef A1 As TestClass)
A1.TestSub()
End Sub
After all This I want to create a thread and run the sub "DoMyStuff" by Passing a reference of X1
To Do this I have Imported System Threading:
Imports System.Threading
Inside Module after initialization of X1 and X2 I have written:
Dim T1 as New Threading.Thread(AddressOf DoMyStuff)
T1.Start(X1)
Here I am getting error: Overload Resolution Failed because no 'New' can be called with this arguments: 'Public Sub New(Start As System.Threading.ParameterizedThreadStart, maxStackSize As Integer)': Method 'Public Sub DoMyStuff(ByRef A1 As TestClass)' does not have a signature compatible with delegate 'Delegate Sub ParameterizedThreadStart(obj As Object)'. 'Public Sub New(Start As System.Threading.ThreadStart, maxStackSize As Integer)': Method 'Public Sub DoMyStuff(ByRef A1 As TestClass)' does not have a signature compatible with delegate 'Delegate Sub ThreadStart()'.
If I am writing like this,
Dim T1 As Threading.Thread
T1 = (AddressOf DoMyStuff)
T1.Start(X1)
I am getting the error: 'AddressOf' expression can not be converted to 'System.Threading.Thread' because 'System.Threading.Thread' is not a delegate type.
Might be I am missing some thing, which I am unable to find. I am not so much good in Delegate type concept. Also this is my first project with implementation of Threading. Looked for answers in Google but unable to understand to sort out. Your help highly solicited.
Thanks
Edit:
I have checked your reference Michael Z. and its really helpful. First of all a big Thank you for that :)
However, I am unable to understand a thing in there. If you help me out there, I would be highly grateful. As per my understanding, I have changed my code as below:
Public Delegate Sub Test2(ByRef A1 as TestClass)
Public T1 as Test2 = New Test2(AddressOf DoMyStuff)
Public Sub DoMyStuff(ByRef A1 as TestClass)
A1.TestSub()
End Sub
Now I have Declared in my module as follows:
Dim T as Threading.Thread = New Threading.Thread(AddressOf DoStuff)
Here I am unable to understand how to write the DoStuff sub as in your example you were working with TextBox1 which is an object in UI, so you wrote:
Public Sub DoStuff()
If TextBox1.InvokeRequired Then
TextBox1.Invoke(T1,"Hello")
End If
End Sub
But here I need to work with an object which is custom made i.e. X1 or X2. Also I need to pass the reference of the object in the Thread so that the method TestSub can work with the created object either X1 or X2. Totally lost here :(
Please correct me if anywhere I am wrong to understand your reference, otherwise if correctly understood, can you Please help me out here. Appreciate your help in advance.
Thanks
Firstly, ensure you're calling this from a method:
Dim T1 as New Threading.Thread(AddressOf DoMyStuff)
T1.Start(X1)
Next remove the ByRef in the method parameter like so Sub DoMyStuff(A1 As TestClass)
Essentially make your second Module look like:
Module Module2
Dim X1 As New TestClass("Some String", "asd")
Dim X2 As New TestClass("Some String", "Some String")
Sub TestCall
Dim T1 as New Thread(AddressOf DoMyStuff)
T1.Start(X1)
End Sub
Private Sub DoMyStuff(A1 As TestClass)
A1.TestSub()
End Sub
End Module
And you can call it like so:
TestCall()
Try using a simple Call method;
Call New Threading.Thread(AddressOf DoMyStuff).Start(X1)
Looking at what you wanting, there seems no reason to assign this to a variable?
Also - remember, when working with multiple contructors, you need to ensure the [TYPES] you pass in are correct and expected (this could be why your current process isn't working).
See this link for a similar issue.
So i am making a virtual os and im making a new user function.In the Login form i used a combobox for Selecting users and i'm stuck at creating a method to add the input for the new user to the combobox collection. this is what i have right now
Public Class NewUser
Private Sub FlatButton2_Click(sender As Object, e As EventArgs) Handles FlatButton2.Click
Form1.UserName(1) = FlatTextBox1.Text
Form1.FlatComboBox1.Items.Add = FlatTextBox1.Text
End Sub
End Class
i know its not much yet. but when i excecute this code it gives an error:Argument not specified for parameter 'item' of 'Public Function Add(item As Object) As Integer.
i really dont get how to fix this error.
Can someone help me please?
Add isn't a property, it's a method on ComboBox.ObjectCollection with one parameter, an Object. You need to invoke it like so
Form1.FlatComboBox1.Items.Add(FlatTextBox1.Text)
See the documentation for more info.
Public Class notifierMain
Public Class Contacts
Inherits List(Of row)
Public Sub New()
Dim r As New row()
Me.Add(r)
End Sub
Public Class row
Public Sub Validate()
Dim curType As String = Me.GetType().ToString
End Sub
End Class
End Class
Public Class MyContacts
Inherits contacts
End Class
Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
Dim c As MyContacts = New MyContacts()
c(0).Validate()
End Sub
End Class
When I debug this winforms application I get curType = "notifier.notifierMain+Contacts+row"
I want to the Validate function to know it is in MyContacts. How do I do this?
You're tostring()'ing gettype which returns a property called full name.
just check the .Name after get type and that'll have the result you want.
btw: this is a weird example, if you want validate() to return the name of the class you'll have to declare it as a function.
:)
The Me.GetType() is always going to return the type of the class it is enclosed in.
You will need to change Validate to a function and pass in the type of object being validated, but then you might as well call c(0).GetType() outside if the validation anyway!
See MSDN documentation for GetType
You can explore your generic type as shown in this MSDN article:
http://msdn.microsoft.com/en-us/library/b8ytshk6.aspx
Hope this helps.
I am trying to create a settings class.
The Property Test() is a list of strings.
When I add a string such as: t.test.Add("asasasAAAAA")
I want it to autmatically turn lowercase.
For some reason it is not. Any Ideas?
p.s.
using t.test.Add(("asasasAAAAA").ToLower) will not work for what I need.
Thank you.
Public Class Form1
Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
Dim t As New Settings
t.test.Add("asasasAAAAA")
t.test.Add("aBBBBBAAAAA")
t.test.Add("CCCCCsasAAAAA")
End Sub
End Class
Public Class Settings
Private strtest As New List(Of String)
Public Property test() As List(Of String)
Get
Return strtest
End Get
Set(ByVal value As List(Of String))
For i As Integer = 0 To value.Count - 1
value(i) = value(i).ToLower
Next
strtest = value
End Set
End Property
End Class
ashakjs
That's the reason: set accessor of your property is actually never called.
when you use t.test.Add("asasasAAAAA") you are actually calling a get accessor, which returns a list, after that specified string is added to this list, so .ToLower function is never called.
Simple way to fix this:
Dim list as New List(Of String)
list.Add("asasasAAAAA")
list.Add("aBBBBBAAAAA")
list.Add("CCCCCsasAAAAA")
t.test = list
Alternatively, you can implement your own string list (easiest way - inherit from Collection (Of String)), which will automatically convert all added string to lower case.
What you are trying to do and what you are doing don't match. To do what you want, you need to create your own collection class extending the generic collection - or provide a custom method on your settings class which manually adjusts the provided string before adding it to the local (private) string collection.
For an example of the second option, remove the public property of the settings class which exposes the list of string and use a method like the following:
Public Sub Add(ByVal newProp As String)
strtest.Add(newProp.toLower())
End Sub