CODEWITHSUNDEEP
vb.netlistcollectionscombobox
SilentUK
SilentUK

Reputation: 195

Adding List of Objects to Dropdown Combobox in Visual Basic

I am pretty new to Visual Basic and mostly create through trial and error but I've been attempting this for about 5 hours now and have had no luck. I am trying to create a program used at events for runners. It has multiple forms. There are two forms to create Runners and Races. These are then stored in the Runner and Race Collection Lists. I want to populate a dropdown box with the races that are stored in the race collection list. The closet I have got to achieving this so far is the dropdown displaying "{}collection". I have tried .datasource, .add and .addRange. None seem to work.

My race collection code is:

Public Class RaceList
    Inherits System.Collections.CollectionBase

    Public Sub Add(ByVal aRace As Race, Optional ByVal key As String = "NewRace")

        List.Add(aRace)
    End Sub
    Public ReadOnly Property Item(ByVal index As Integer) As Race
        Get

        Return CType(List.Item(index), Race)
    End Get
End Property
End Class

it should simply allow the user to add too and return races in the list.

Here is the code that allows the user to add a race to the list:

Public Class newRaceForm
    Public Shared racelist As New RaceList
    Private Sub uiBtnAddNewRace_Click(sender As System.Object, e As System.EventArgs) Handles uiBtnAddNewRace.Click

        uiDTPRaceDate.Text = Today

        Dim x As Date
        Dim champ As Boolean = False
        x = uiDTPRaceDate.Text
        If uiCheckboxChampion.Checked = True Then
            champ = True
        End If

        Dim race As New Race(x, champ)

        uiCheckboxChampion.Checked = False

        MsgBox("Race Added")
        racelist.Add(race, race.uniqueRaceID)
    End Sub

Finally, Here is the code on the form_load that should populate the box with the contents of racelist.

Private Sub finishRaceForm_Load(sender As System.Object, e As System.EventArgs) Handles MyBase.Load
    Dim x = 0
    Dim races As New RaceList

    While x < races.Count
        uiDropDownRace.Items.Add(races.Item(x).ToString)
        x = x + 1
    End While

End Sub

Also, my races class is created as such:

Public Class Race
Private raceDate As String
Private isChampionship As Boolean
Public Shared RaceID As Integer = 0
Public uniqueRaceID As String


Sub New(ByVal x As String, champ As Boolean)

    raceDate = x

    If champ = True Then
        isChampionship = True
    Else
        isChampionship = False
    End If

    RaceID = RaceID + 1
    uniqueRaceID = "RaceID0" + RaceID.ToString

End Sub
End Class

Upvotes: 1

Views: 4516

Answers (2)

Justin Woodmancy
Justin Woodmancy

Reputation: 952

I'm working on a similar program and got it to work by using this. 

Dim CmbAcro As String() = {"INSERT", "THE", "ITEMS", "YOU", "WANT", "TO", "ADD", "TO", "A", "COMBO", "BOX"}

Dim cmb As New DataGridViewComboBoxColumn()

cmb.HeaderText = "INSERT HEADER TEXT HERE"
cmb.Name = "INSERT NAME HERE"
cmb.MaxDropDownItems = 20
cmb.Sorted = True

For Each i In CmbAcro
                cmb.Items.Add(i)
            Next
            DataGridView1.Columns.Add(cmb)

Upvotes: 1

Andrew Neely
Andrew Neely

Reputation: 908

Whenever you add an object to a list box or drop down list, the the ToString function is called, to determine what is going to be shown.

Most objects default to returning their type name as their ToString Function. You can overrride the ToString function to display whatever you wish. In the example below, I display the text "Race Number x" where x is the race number.

Public Class Race
    Private raceDate As String
    Private isChampionship As Boolean
    Public Shared RaceID As Integer = 0
    Public uniqueRaceID As String


    Sub New(ByVal x As String, champ As Boolean)
        raceDate = x

        If champ = True Then
            isChampionship = True
        Else
            isChampionship = False
        End If

        RaceID = RaceID + 1
        uniqueRaceID = "RaceID0" + RaceID.ToString

    End Sub
    Public Overloads Function ToString() As String
            Return "Race Number " & RaceID.ToString()
End Function
End Class

Upvotes: 1

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