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.
Related
what is the correct way to call function outside the class, below code is also working
tried an alternate way by using delegate but couldn't figure out to pass function with parameters from Form class to classname so that form function can be called.
Public class form1
Private Sub Button1_Click(sender As Object, e As EventArgs) Handles Button1.Click
dim cl as new classname
cl.run()
end sub
function testmsg(txt as string)
msgbox(txt)
end function
end class
public class classname
public sub run()
txt = "xyz"
if(condition = true) then call form1.testmsg(byref txt as string)
end sub
end class
You can at any time, and in any place, and from a form, a class object, or even just standard vb module call/use a function (or in your case, it should be a sub).
Just mark any routine (sub/function) in the form as public.
eg:
Public function testmsg(txt as string)
msgbox(txt)
end function
NOw, in any other form, class or in fact any place you have code, you can thus go:
FormA.TestMsg("hi from form B")
so, there are no restrictions here. And any form wide scoped variables marked as public can also be used:
eg:
Public Class FormA
Public Zoo As String
Public Function TestMsg(txt As String)
MsgBox(txt)
End Function
Public Sub ShowZoo()
MsgBox("value of zoo = " & Zoo)
End Sub
End Class
So above is FormA
Now, any code from any ohter form, class or whatever can do this:
FormA.TestMsg("hi from form B")
FormA.Zoo = "this is zoo value"
FormA.ShowZoo()
So, just mark any variable as public (it in effect becomes a public property of that form).
And, just mark any function/Sub as pubic (it in effect becomes a public "method" of that form.
Here's my problem.
I'm making a project in VB.NET that (currently) exists out of 1 class (let's call it User.vb here) and 2 WinForms (frmDisplay & frmMain).
Let's say User.vb is currently looking like this:
Public Class User
Private mName As String
Public Sub New(ByVal name As String)
Me.Name = name
End Sub
Public Property Name As String
Get
Return mName
End Get
Set(value As String)
mName = value
End Set
End Property
End Class
Let's also say the form frmDisplay is just a form with a textfield txtString and a button btnSend.
Public Class frmDisplay
Dim usr As New User()
Private Sub btnSend_Click(sender As Object, e As EventArgs) Handles btnSend.Click
usr.Name = txtString.Text
frmMain.Show()
Me.Hide()
End Sub
End Class
On the form frmMain I want to reach the value in the property Name that I stored in the class User on the first form.
The basic idea is (I know it doesn't work):
Public Class frmMain
Private Sub frmMain_Load(sender As Object, e As EventArgs) Handles MyBase.Load
lblStoredString.Text = usr.Name << This is where I'm stuck
End Sub
End Class
I googled my problem and read many posts, but I just can't seem to understand it. Maybe you guys can help me. I am new to VB.NET and WinForm-stuff (about 3 months of exp.), but I have done some programming in the past in C# with webapplications.
Every bit of help is greatly appreciated.
Thanks a lot in advance!
Will there only ever be one User.Name that you are interested in throughout the app?
If yes, then change the class to:
Public Class User
Public Shared Name As String
End Class
Then you can use User.Name from any form (or anywhere in the application) to get/set that value.
Note that you can still wrap the field in a property if you like:
Public Class User
Private Shared _Name As String
Public Shared Property Name As String
Get
Return _Name
End Get
Set(value As String)
If (value.Trim <> "") Then
_Name = value.Trim
End If
End Set
End Property
End Class
My focus is ASP.NET, and I prefer C#, but I'll chime in. There are numerous ways of providing data between the forms. The first one that comes to mind is to use a cache of some kind. The idea is that once the cache is made available to your program, you can add the value to the cache when the button is clicked, and then safely read the value whenever you need it. This can be a static class with a Dictionary, or you can look into using the functionality provided by the System.Web.Caching namespace. http://www.codeproject.com/Articles/8977/Using-Cache-in-Your-WinForms-Applications has an example.
Another way would be to use a shared data source. The concept is similar to the caching, but this would allow you to pass more complex relational data between your forms, assuming your real goal is more complicated than you describe. Here is a walkthrough for that: https://msdn.microsoft.com/en-us/library/ms171925.aspx.
You could be quick and dirty, and write the values to a text file at some location, and then read the values from the second form.
The simplest way is probably to define a custom constructor for the second form, and pass the values you need when you instantiate the second form. This is best suited if the values from the first form can be considered "parameters" to the instance of the second form. Passing a textbox value from one form to another in windows application
Declare the usr variable Friend
Public Class frmDisplay
Friend usr As New User()
It will then be available from the other form
Public Class frmMain
Private Sub frmMain_Load(sender As Object, e As EventArgs) Handles MyBase.Load
lblStoredString.Text = frmDisplay.usr.Name
End Sub
End Class
It's a quirk of VB.NET that forms are automatically created with a public variable name the same as the class name. That's why you are able to use frmMain without having to create it (e.g. Dim frmMain as New frmMain). You can turn off this behaviour, but it isn't relevant to your problem.
On the other hand, if you want to do it "properly"...
Public Class frmDisplay
Private usr As User
Private Sub btnSend_Click(sender As Object, e As EventArgs) Handles btnSend.Click
usr = New User(txtString.Text)
Dim f As New frmMain(Me, usr)
f.Show()
Me.Hide()
End Sub
End Class
and frmMain...
Public Class frmMain
Private myParent As Form
Private usr As User
Sub New(parent As Form, _usr As User)
' This call is required by the designer.
InitializeComponent()
' Add any initialization after the InitializeComponent() call.
usr = _usr
myParent = parent
End Sub
Private Sub Form2_Load(sender As Object, e As EventArgs) Handles MyBase.Load
Label1.Text = usr.Name
End Sub
Private Sub frmMain_FormClosed(sender As Object, e As FormClosedEventArgs) Handles Me.FormClosed
myParent.Show()
End Sub
End Class
Here we instantiate frmMain and pass the User object to its constructor. We also pass the calling form so we can display it again when frmMain is closed.
I am getting the error message "Structure cannot be indexed because it has no default property". can anyone please show me what I'm doing wrong?
Public Structure Length8FixedString
<VBFixedString(8)> Public myFixedString As String '8 is the STRING length.
End Structure
Public Structure ExampleStructure2
<VBFixedArray(7)> Public myArray As Length8FixedString
End Structure
Public Class Form1
Private Sub Button1_Click(sender As Object, e As EventArgs) Handles Button1.Click
Dim V As New ExampleStructure2
V.myArray(1) = "TIM" 'ERROR: Structure cannot be indexed because it has no default property
End Sub
End Class
You declared myArray as type FixedLengthString instead of as an array of FixedLengthString:
Public Structure ExampleStructure2
<VBFixedArray(7)> Public myArray As Length8FixedString()
End Structure
Not sure if this is what you want because this exposes more problems. An explanation of what you're trying to achieve will help if this isn't the answer.
can we have a single global variable which can be manipulated by multiple forms
In short, yes. You can have a global variable in a module (.mod) file or a class (.vb) file.
Module Module2
Public variable As String = "Testing"
End Module
Declare a variable like this:
Public Shared myVariable as Type
and access it from any form.
You can access a single variable from any form, if it is declared as public.
If you are defining it in form1 and want to use it in form2, then from inside form2 you can call the variable as - form1.<variable_name>
Take an example-
Form1 code
Public Class Form1
Public a As Integer = 10
Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
Form2.Show()
End Sub
End Class
Form 2 code
Public Class Form2
Private Sub Form2_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
MsgBox(Form1.a)
End Sub
End Class
Yes, it can be done. If you declare it as shared it will exist in only one instance.
Public Class SomeClass
Public Shared SomeField As String
End Class
I would, however, recommend to wrap access to the field into a property:
Public Class SomeClass
Private Shared _someValue As String
Public Shared Property SomeProperty() As String
Get
Return _someValue
End Get
Set(ByVal value As String)
_someValue = value
End Set
End Property
End Class
By wrapping it into a property you will make it easier to troubleshoot problems around the value in case such scenarios would appear in the future.
What you are looking for is the "singleton pattern".
But first, you should ask yourself if you really need it. Maybe this variable could be passe as a parameter to a function or a property.
Use
Public x As Integer
On any Of the Forms and then when you want to use that variable on other form then you can type the form name and then a dot and then the variable name
like this
form1.x
Cheers!!!
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