在 Visual Basic 中将对象列表添加到下拉组合框中

Question

我对 Visual Basic 还是很陌生，主要是通过反复试验来创建，但我已经尝试了大约 5 个小时，但没有运气。我正在尝试创建一个用于跑步者活动的程序。它有多种形式。创建 Runners 和 Races 有两种形式。然后将这些存储在 Runner 和 Race Collection List 中。我想用存储在比赛集合列表中的比赛填充一个下拉框。到目前为止，我要实现这一目标的壁橱是显示“{}collection”的下拉菜单。我尝试过 .datasource、.add 和 .addRange。似乎没有一个工作。

我的比赛收集代码是：

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

它应该只允许用户在列表中添加和返回种族。

这是允许用户将比赛添加到列表的代码：

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

最后，这是 form_load 上的代码，它应该用racelist的内容填充框。

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

另外，我的比赛类是这样创建的：

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

Answer 1

我正在开发一个类似的程序，并通过使用它使其工作。

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)

Answer 2

每当您将对象添加到列表框或下拉列表时，都会调用 ToString 函数以确定要显示的内容。

大多数对象默认返回它们的类型名称作为它们的 ToString 函数。您可以覆盖 ToString 函数以显示您想要的任何内容。在下面的示例中，我显示文本“比赛编号 x”，其中 x 是比赛编号。

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