VB.net集合

Question

Class MainWindow

    Dim states As Collection = New Collection()

    Sub Output(Value As String)

        txtOutput.Text += Value + vbCrLf

    End Sub

    Sub ClearOutput(sender As Object, e As RoutedEventArgs) Handles btnClear.Click
        txtOutput.Text = ""
        txtInput.Text = ""
    End Sub

    Sub btnAdd_Click(sender As Object, e As RoutedEventArgs) Handles btnAdd.Click

        Dim input As String = txtInput.Text
        'Dim state As String = input.Substring(0, input.IndexOf(",")).ToString
        'Dim stateID As String = input.Substring(input.IndexOf(" ")).ToString

        states.Add(input)
        Output("You added: " + input)

    End Sub

    Sub btnGet_Click(sender As Object, e As RoutedEventArgs) Handles btnGet.Click

        Dim stateID As String = txtInput.Text.ToString
        If states.Contains(stateID) Then
            Output("You requested: " + states.Item(stateID))
        Else
            Output("Not found")
        End If
    End Sub

    Sub btnRemove_Click(sender As Object, e As RoutedEventArgs) Handles btnRemove.Click

        Dim stateID As String = txtInput.Text.ToString
        If states.Contains(stateID) Then
            states.Remove(stateID)
            txtOutput.Text = ""
            Output(stateID + " removed; here's what's left:")
            OutputStates()
        Else
            Output("Not found")
        End If

    End Sub

    Sub btnShow_Click(sender As Object, e As RoutedEventArgs) Handles btnShow.Click
        OutputStates()
    End Sub

    Sub OutputStates()
        For Each state As String In states
            Output(state)
        Next
    End Sub
End Class

我完成了“添加并显示”按钮。 输入是：CA，California

但是我的问题是删除并获取按钮。 例如，我输入“ CA”作为stateID，如果单击“获取”或“删除”按钮，它将检查状态集合中是否包含带有“ CA”字符串的项目，但是即使我使用状态（1，也始终找不到答案） ）。包含位于美国加利福尼亚州加利福尼亚的（stateID）

Answer 1

在.NET中，您将使用HashSet(Of T) 。

Dim states As HashSet(Of String) = New HashSet(Of String)()

states.Add(stateID)

If states.Contains(stateID) Then ...

请注意，HashSet默认情况下区分大小写。 如果您希望它不区分大小写，请像下面这样初始化它：

Dim states As HashSet(Of String) = New HashSet(Of String)(StringComparer.OrdinalIgnoreCase)

---

还要注意，（使用Collection ） states(1)返回一个stateID 。 因此，您可以比较

states(1) = stateID 'Should return True if 1st state is "CA" and stateID is "CA"

states(1).Contains(stateID)没有任何意义。 此处Contains可能是指state(1) Contains的字符。