Question

我是Visual Basic的新手，主要通过反复试验来创建，但我现在已经尝试了大约5个小时并没有运气。我正在尝试为赛跑者创建一个用于赛事的程序。它有多种形式。创建Runners和Races有两种形式。然后将它们存储在Runner和Race Collection Lists中。我想用一个存储在种族收集列表中的种族填充一个下拉框。到目前为止，我必须实现这个目标的是显示“{}集合”的下拉列表。我试过.datasource，.add和.addRange。似乎没有用。

我的种族收集代码是：

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

它应该只允许用户添加并返回列表中的种族。

以下是允许用户将竞赛添加到列表中的代码：

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的内容填充该框。

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

此外，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

无论何时将对象添加到列表框或下拉列表中，都会调用ToString函数来确定要显示的内容。

大多数对象默认返回其类型名称作为其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“Race Number x”，其中x是比赛号码。

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

Answer 2

我正在研究类似的程序并使用它来使其工作。

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)

在Visual Basic中将对象列表添加到Dropdown Combobox

2 个答案: