class containing another class

Hi, I'm new to OOP and am having problems creating a class that contains a collection of items from another class. ie I have a LabelTemplate class that represents a label to printed from a Thermal label printer. My LabelTemplate class has a set of properties like label size, labelName,barcode string etc.I also have a class, "PrintFields", that contains properties for a dynamic number of different items to be printed on the label. I want to have this class contain and access a collection of PrintField objects. Any ideas

Regards
Kev

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class containing another class

buladbanaw
Hi,

To have a collection of class in your class then try this pseudo-code:

Public Class PrintField
   Public fieldValues as String
End Class

Public Class LabelTemplate
   Private fieldValues As New Collection

   Public Function getfieldValue(index As Integer) As PrintField
      Dim retVal As PrintField
      retVal = fieldValues(index)
      ' return the value
   End Function

   public Sub setFieldValue(f As PrintField)
      ' Add the new value in the collection
   End Sub
End Class
' Also implement the Remove() function

Or you could just simply expose your collection by making it public...

cheers,

Paul June A. Domag
Andrea_A
Thanks Paul, I just aboutr have it, I think .
The problem is Button3 click causes an error.Would you mind helping, I guess the answer must be obvious but I can't see it.

Public Class PrintField
    Private xposValue As Integer
    Public Property xpos() As Integer
        Get
            Return xposValue
        End Get
        Set(ByVal value As Integer)
            xposValue = value
        End Set
    End Property

    Private yposValue As Integer
    Public Property ypos() As Integer
        Get
            Return yposValue
        End Get
        Set(ByVal value As Integer)
            yposValue = value
        End Set
    End Property
End Class

Public Class LabelTemplate
    Private PrintFields As New Collection

    Public Function getfldValue(ByVal index As Integer) As PrintField
        Dim retVal As PrintField
        retVal = CType(PrintFields(index), PrintField)
        ' return the value
    End Function

    Public Sub setFldValue(ByVal f As PrintField)
        PrintFields.Add(f)
    End Sub

    Private FieldcountValue As Integer
    Public ReadOnly Property Fieldcount() As Integer
        Get
            FieldcountValue = PrintFields.Count
            Return FieldcountValue
        End Get
    End Property
End Class

Public Class Form3
    Private anitem As New PrintField
    Private nextitem As New PrintField
    Private mylabel As New LabelTemplate

    Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
        anitem.xpos = 1111
        anitem.ypos = 2222
        mylabel.setFldValue(anitem)
        nextitem.xpos = 3333
        nextitem.ypos = 4444
        mylabel.setFldValue(nextitem)
    End Sub

    Private Sub Button2_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button2.Click
        MsgBox(mylabel.getfldValue(0).xpos.ToString)
    End Sub

    Private Sub Button3_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button3.Click
        'This causes an error
        MsgBox(mylabel.getfldValue(1).ypos.ToString)

    End Sub

    Private Sub Button4_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button4.Click
        MsgBox(mylabel.Fieldcount.ToString) 'This works
    End Sub
End Class
jasMSDN
There's 2 ways you can do this.

1, is to inherit the class.
------------------------
Example.
Public Class Drink
   Public sub Drink()
   End Sub

   Public sub Refill()
   End sub
End Class

Public class Coffee
   Inherits Drink

   Public Sugars as Integer
   Public Creams as Integer

   Public Sub GetCoffee()
      Refill()
   End sub

   Public Sub DrinkCoffee()
      Drink()
   End sub
End Class
--------------------------------

The other option, is to make a local variable of the class.

Exmaple.
Public Class Drink
   Public sub Drink()
   End Sub

   Public sub Refill()
   End sub
End Class

Public class Coffee
   private MyDrink as Drink = New Drink

   Public Sugars as Integer
   Public Creams as Integer

   Public Sub GetCoffee()
      MyDrink.Refill()
   End sub

   Public Sub DrinkCoffee()
      MyDrink.Drink()
   End sub
End Class
Mr PoPoP
Hi,

In your getFldValue() function, what I meant by return the value was declaring Return retVal coz at that time I was not sure on the return keyword in VB...

cheers,

Paul June A. Domag
class containing another class

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