如何从另一个类 VB.NET 向数组添加项

Question

Okay, so I have a class element, and a form.

I have an Array inside my class element, and I need it to set it from a form...

basically what I'm doing:

----Form1----

*DataClass.VarArray()*

---

----DataClass----

Public VarArray() As String

---

And I need to know, how do I add an item to an array, and also how to get it from another class... Please

I Already Tried Different Methods, Like Making A List But that Did not work

Answer 1

NEW:

So, I added a TextBox and a RichTextBox to the form...

TextBoxUserName(TextBox): contains the username that we are going to enter to the list

TextBoxListOfUsers(RichTextBox): contains the usernames addedd throught the button... is only to get a view of what we are doing.

Now when you click the NewUserBT button you will add a string (the user name) to the list if is not blank, white spaces, is not yet contained ecc...

Check out and tell me...

Public Class Form1
    ' Declare "usersClass" and its type
    Dim usersClass As DataClass

    Public Sub New()
        InitializeComponent()
        ' now give to "usersClass" a value, an instance, so...
        usersClass = New DataClass()
    End Sub

    Public Sub NewUserBT_Click() Handles NewUserBT.Click
        Dim new_user As String = Me.TextBoxUserName.Text

        ' If is not blank, empty or white spaces, and is not contained in the list...
        If Not String.IsNullOrEmpty(new_user) AndAlso Not String.IsNullOrEmpty(new_user) AndAlso Not Me.usersClass.usersNameList.Contains(new_user) Then
            usersClass.usersNameList.Add(new_user)
            Me.TextBoxListOfUsers.Text += new_user + vbCrLf ' name + linefeed
        End If
    End Sub
End Class

Public Class DataClass
    ' Declare "usersNameList" var and its type
    Public usersNameList As List(Of String)

    Public Sub New()
        ' When we "usersClass = New DataClass()" we will go here and set the instance of userNameList
        usersNameList = New List(Of String)
    End Sub
End Class

OLD:

Public Class Form1
    Dim foo As ArrayClass

    Public Sub New()
        InitializeComponent()
        foo = New ArrayClass()
    End Sub

    Public Sub pippo() Handles Button1.Click
        foo.array(1) = "something"
        Button1.Text = foo.array(1)
    End Sub
End Class

Public Class ArrayClass
    Public array(10) As String

    Public Sub New()

    End Sub
End Class

This might be what you are looking for... I think. You can use the array in the form class, give it a try.

Tip:

Dim strings_list As List(Of String) ' this is a list of strings
Dim strings_array(10) As String ' this is an array to hold 10 strings

Answer 2

I would recommend using a List(Of T) instead of an array if you don't know up front what the size will be.

I changed your field to a property. Fields are usually private.

In the button click event, I first had to declare an instance of the class. Then use the instance variable to assign an item to the list.

Public Class Data
    Public ReadOnly Property lst As New List(Of String)

End Class
Private Sub Button1_Click(sender As Object, e As EventArgs) Handles Button1.Click
    Dim dat As New Data
    dat.lst.Add("Hello")
End Sub

Using a field and an array

Public Class Data
    Public VarArray(10) As String 'Array needs a size to be created
End Class
Private Sub Button1_Click(sender As Object, e As EventArgs) Handles Button1.Click
    Dim dat As New Data
    dat.VarArray(0) = "Hello"
    Debug.Print(dat.VarArray(0))
End Sub

This particular VarArray will only be a part of a particular instance of the Data class. Same is true of the list. To share the data you would make the property/field Shared. You can then reference as Data.VarArray or Data.lst in the Form.