将变量写入VB.Net中的预先存在的数组

Question

我目前正在使用Framework 4.0设计一个电影客户预订系统的模型。 目前所有数据都将存储在一个数组中，因为它是一个模型，它将保留其（客户名称，票价等...），因为此时无需永久存储数据。

我有一个GUI表单和两个主要类，MainForm.vb用于处理应用程序的I / O功能，而SeatManager.vb用于管理要运行以使程序运行的后台方法。 每个类的代码如下： -

**MainForm.vb Class**
    Public Class MainForm
        Private Const m_totalNumberOfSeats As Integer = 60
        Private m_seatManager As SeatManager

        Public Sub New()

            InitializeComponent()
            m_seatManager = New SeatManager(m_totalNumberOfSeats)
            InitializeGUI()
        End Sub

        ''' <summary>
        ''' Method called from the MainForm() method. This method is called when the form
        ''' is opened by the program (on initialisation).
        ''' </summary>
        Private Sub InitializeGUI()
            rbtnReservation.Checked = True              'Sets the Reserve button as being chosen
            lstReservations.Items.Clear()               'Clears the list displaying all seats and reservations
            txtCustomerName.Text = String.Empty         'Sets the name textbox as emtpy
            txtSeatPrice.Text = String.Empty

            cmbDisplayOptions.Items.AddRange([Enum].GetNames(GetType(SeatManager.DisplayOptions)))
            cmbDisplayOptions.SelectedIndex = SeatManager.DisplayOptions.AllSeats

            For i As Integer = 0 To m_totalNumberOfSeats - 1
                lstReservations.Items.Add(GetMyString(i))
            Next
        End Sub
        Private Function GetMyString(ByVal i As Integer) As String
            If i >= 0 AndAlso i < m_totalNumberOfSeats Then
                Return String.Format("{0}{1}{2}{3}", GetPaddedString(m_seatManager.MyArray(i, 0), 29), _
                                     GetPaddedString(m_seatManager.MyArray(i, 1), 41), _
                                     GetPaddedString(m_seatManager.MyArray(i, 2), 63), _
                                     m_seatManager.MyArray(i, 3))
            Else
                Return String.Empty
            End If
        End Function

        Private Function GetPaddedString(ByVal o As Object, ByVal length As Integer) As String
            Dim s As String = String.Empty
            If o IsNot Nothing Then s = o.ToString()
            If s.Length > length Then s = s.Substring(0, length)
            Return s.PadRight(length - s.Length)
        End Function

        '--Event Handler when you change the value of Customer Name/Price
        '    Dim index As Integer = lstBox.selectedIndex
        'm_arrayClass.PopulateArray(index,customerName.text, ctype(price.text,double))
        'lstBox.Items(index) = GetMyString(index)

        'Private Function CheckSelectedIndex() As Boolean
        '    If lstReservations.SelectedIndex <= 0 Then
        '        Return lstReservations.SelectedIndex
        '    Else
        '        Return False
        '    End If
        'End Function

        ''' <summary>
        ''' Method uses to verify that the user has entered text within the txtName textbox
        ''' </summary>
        ''' <param name="name">String variable passing the customer name inputted by the user</param>
        ''' <returns>True if validation confirms user has entered at least one character in
        ''' the txtName field otherwise returns False. If returns false, an error message will
        ''' be displayed to the user</returns>
        Private Function ReadAndValidateName(ByRef name As String) As Boolean
            If (String.IsNullOrEmpty(txtCustomerName.Text)) Or (String.IsNullOrEmpty(txtCustomerName.Text)) Then
                MessageBox.Show("You have not entered a valid customer name. Please try again", _
                                "Invalid Customer Name", MessageBoxButtons.OK)
                txtCustomerName.Focus()
                txtCustomerName.SelectAll()
                Return False
            Else
                Return True
            End If
        End Function

        ''' <summary>
        ''' This method calls the GetDouble() method in the InputUtility class to convert the text
        ''' given by the user in the txtPrice textbox. 
        ''' </summary>
        ''' <param name="seatPrice">Output parameter receiving the converted value</param>
        ''' <returns>True if conversion is successful and validates or False. If returns False
        ''' an error message will be displayed to the user.</returns>
        Private Function ReadAndValidatePrice(ByRef seatPrice As Double) As Boolean
            If (InputUtility.GetDouble(txtSeatPrice.Text, seatPrice) And (seatPrice >= 0)) Then
                Return True
            Else
                MessageBox.Show("You have not entered a valid price. Please try again", _
                                "Invalid Price", MessageBoxButtons.OK)
                txtSeatPrice.Focus()
                txtSeatPrice.SelectAll()
                Return False
            End If
        End Function

        ''' <summary>
        ''' This method calls the above two methods (validate name and validate price) and if both return true, 
        ''' this method also returns true. If either of the above two methods are false, this method returns false
        ''' </summary>
        ''' <param name="name">Output Parameter - customer name</param>
        ''' <param name="seatPrice">Output parameter - seat price</param>
        ''' <returns>Returns true if validates and false if not</returns>
        Private Function ReadAndValidateInput(ByRef name As String, ByRef seatPrice As Double) As Boolean
            Dim nameResult As Boolean = ReadAndValidateName(name)
            Dim priceResult As Boolean = ReadAndValidatePrice(seatPrice)

            Return ((nameResult) And (priceResult))
        End Function

        Private Sub btnExitApplication_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnExitApplication.Click

            Dim msgConfirmation As Integer
            msgConfirmation = MessageBox.Show("Are You Sure You Wish To Exit This Application?", "WARNING!", _
                                              MessageBoxButtons.YesNo, MessageBoxIcon.Exclamation)
            If msgConfirmation = vbYes Then
                Application.Exit()
            End If
        End Sub
    End Class




**SeatManager.vb Class**            
    Public Class SeatManager
        Private _array(,) As Object
        Dim m_totalNumberOfSeats As Integer

        Public Sub New(ByVal maxNumberOfSeats As Integer)
            m_totalNumberOfSeats = maxNumberOfSeats
            ReDim _array(m_totalNumberOfSeats - 1, 3)
            For i As Integer = 0 To m_totalNumberOfSeats - 1
                PopulateArray(i, Nothing, 0.0)
            Next
        End Sub

        Public ReadOnly Property MyArray() As Object(,)
            Get
                Return _array
            End Get
        End Property

        Public Enum DisplayOptions
            AllSeats
            VacantSeats
            ReservedSeats
        End Enum

        Public Sub PopulateArray(ByVal i As Integer, ByVal CustomerName As String, ByVal Price As Double)
            Dim av As String = "Available"
            If Not String.IsNullOrEmpty(CustomerName) Then av = "Not Available"
            'Did you say this has to be handled in an enum?

            _array(i, 0) = i + 1 'Seat Number
            _array(i, 1) = av
            _array(i, 2) = CustomerName
            _array(i, 3) = Price
        End Sub
    End Class

我现在要实现的是，我有一个名为txtCustomerName的文本框和一个名为txtPrice的文本框。 当用户在这些框中输入名称和价格并在列表框中选择一个条目lstReservations时，我希望状态从Available更改为“Reserved”，并将客户名称和价格输入到相应的数组字段中。

有什么建议么？ 提前致谢

Answer 1

这是使用类型化数据集和xml实现内存数据库的一种非常简单的方法。 您可以创建一个类型化数据集来将数据保存在内存中，甚至可以使用关系数据库结构来确保数据的完整性。 您可以在内存中更改此数据并将数据保存到XML文件并在下次运行时重新加载该文件，或者您可以丢弃它并在每次运行时重新构建它。

以下是一些用于创建示例数据和填充数据集的示例代码。 您可以编写代码以在运行时查询数据集，就像真正的数据库一样。

    Dim SampleDataFileName = "c:\sampledata.xml"

    Dim ds As New dsReservations

    Try
        ds.ReadXml(SampleDataFileName)
    Catch ex As Exception

    End Try

    If ds.Event.Rows.Count = 0 Then
        'No data yet...initialize sample
        ds.Seat.AddSeatRow(1, "21B")
        ds.Seat.AddSeatRow(2, "21C")
        ds.Seat.AddSeatRow(3, "21D")

        ds.Customer.AddCustomerRow(1, "Bob")
        ds.Customer.AddCustomerRow(2, "Ed")
        ds.Customer.AddCustomerRow(3, "Sally")

        ds.Event.AddEventRow(1, #1/1/2012#, "Concert in the park")
        ds.Event.AddEventRow(2, #5/1/2012#, "Parade")



        Dim drRes1 = ds.Reservation.NewReservationRow
        drRes1.EventId = 1
        drRes1.SeatId = 2
        drRes1.CustomerId = 2
        ds.Reservation.AddReservationRow(drRes1)

        'Save our sample data
        ds.WriteXml(SampleDataFileName)
    End If

    'Spit out all our data (ASP.NET)'
    Response.Write(ds.GetXml())

这是数据集，将其命名为“dsReservations.xsd”。 它有四个相关的表（事件，席位，客户和预订）。

<?xml version="1.0" encoding="utf-8"?>
<xs:schema id="dsReservations" targetNamespace="http://tempuri.org/dsReservations.xsd" xmlns:mstns="http://tempuri.org/dsReservations.xsd" xmlns="http://tempuri.org/dsReservations.xsd" xmlns:xs="http://www.w3.org/2001/XMLSchema" xmlns:msdata="urn:schemas-microsoft-com:xml-msdata" xmlns:msprop="urn:schemas-microsoft-com:xml-msprop" attributeFormDefault="qualified" elementFormDefault="qualified">
  <xs:annotation>
    <xs:appinfo source="urn:schemas-microsoft-com:xml-msdatasource">
      <DataSource DefaultConnectionIndex="0" FunctionsComponentName="QueriesTableAdapter" Modifier="AutoLayout, AnsiClass, Class, Public" SchemaSerializationMode="IncludeSchema" xmlns="urn:schemas-microsoft-com:xml-msdatasource">
        <Connections />
        <Tables />
        <Sources />
      </DataSource>
    </xs:appinfo>
  </xs:annotation>
  <xs:element name="dsReservations" msdata:IsDataSet="true" msdata:UseCurrentLocale="true" msprop:Generator_DataSetName="dsReservations" msprop:Generator_UserDSName="dsReservations">
    <xs:complexType>
      <xs:choice minOccurs="0" maxOccurs="unbounded">
        <xs:element name="Customer" msprop:Generator_TableClassName="CustomerDataTable" msprop:Generator_TableVarName="tableCustomer" msprop:Generator_TablePropName="Customer" msprop:Generator_RowDeletingName="CustomerRowDeleting" msprop:Generator_UserTableName="Customer" msprop:Generator_RowChangingName="CustomerRowChanging" msprop:Generator_RowEvHandlerName="CustomerRowChangeEventHandler" msprop:Generator_RowDeletedName="CustomerRowDeleted" msprop:Generator_RowEvArgName="CustomerRowChangeEvent" msprop:Generator_RowChangedName="CustomerRowChanged" msprop:Generator_RowClassName="CustomerRow">
          <xs:complexType>
            <xs:sequence>
              <xs:element name="CustomerId" msprop:Generator_ColumnVarNameInTable="columnCustomerId" msprop:Generator_ColumnPropNameInRow="CustomerId" msprop:Generator_ColumnPropNameInTable="CustomerIdColumn" msprop:Generator_UserColumnName="CustomerId" type="xs:int" />
              <xs:element name="CustomerName" msprop:Generator_ColumnVarNameInTable="columnCustomerName" msprop:Generator_ColumnPropNameInRow="CustomerName" msprop:Generator_ColumnPropNameInTable="CustomerNameColumn" msprop:Generator_UserColumnName="CustomerName" type="xs:string" minOccurs="0" />
            </xs:sequence>
          </xs:complexType>
        </xs:element>
        <xs:element name="Event" msprop:Generator_TableClassName="EventDataTable" msprop:Generator_TableVarName="tableEvent" msprop:Generator_TablePropName="Event" msprop:Generator_RowDeletingName="EventRowDeleting" msprop:Generator_UserTableName="Event" msprop:Generator_RowChangingName="EventRowChanging" msprop:Generator_RowEvHandlerName="EventRowChangeEventHandler" msprop:Generator_RowDeletedName="EventRowDeleted" msprop:Generator_RowEvArgName="EventRowChangeEvent" msprop:Generator_RowChangedName="EventRowChanged" msprop:Generator_RowClassName="EventRow">
          <xs:complexType>
            <xs:sequence>
              <xs:element name="EventId" msprop:Generator_ColumnVarNameInTable="columnEventId" msprop:Generator_ColumnPropNameInRow="EventId" msprop:Generator_ColumnPropNameInTable="EventIdColumn" msprop:Generator_UserColumnName="EventId" type="xs:int" />
              <xs:element name="EventDate" msprop:Generator_ColumnVarNameInTable="columnEventDate" msprop:Generator_ColumnPropNameInRow="EventDate" msprop:Generator_ColumnPropNameInTable="EventDateColumn" msprop:Generator_UserColumnName="EventDate" type="xs:dateTime" minOccurs="0" />
              <xs:element name="EventName" msprop:Generator_ColumnVarNameInTable="columnEventName" msprop:Generator_ColumnPropNameInRow="EventName" msprop:Generator_ColumnPropNameInTable="EventNameColumn" msprop:Generator_UserColumnName="EventName" type="xs:string" minOccurs="0" />
            </xs:sequence>
          </xs:complexType>
        </xs:element>
        <xs:element name="Seat" msprop:Generator_TableClassName="SeatDataTable" msprop:Generator_TableVarName="tableSeat" msprop:Generator_TablePropName="Seat" msprop:Generator_RowDeletingName="SeatRowDeleting" msprop:Generator_UserTableName="Seat" msprop:Generator_RowChangingName="SeatRowChanging" msprop:Generator_RowEvHandlerName="SeatRowChangeEventHandler" msprop:Generator_RowDeletedName="SeatRowDeleted" msprop:Generator_RowEvArgName="SeatRowChangeEvent" msprop:Generator_RowChangedName="SeatRowChanged" msprop:Generator_RowClassName="SeatRow">
          <xs:complexType>
            <xs:sequence>
              <xs:element name="SeatId" msprop:Generator_ColumnVarNameInTable="columnSeatId" msprop:Generator_ColumnPropNameInRow="SeatId" msprop:Generator_ColumnPropNameInTable="SeatIdColumn" msprop:Generator_UserColumnName="SeatId" type="xs:int" />
              <xs:element name="SeatLocation" msprop:Generator_ColumnVarNameInTable="columnSeatLocation" msprop:Generator_ColumnPropNameInRow="SeatLocation" msprop:Generator_ColumnPropNameInTable="SeatLocationColumn" msprop:Generator_UserColumnName="SeatLocation" type="xs:string" minOccurs="0" />
            </xs:sequence>
          </xs:complexType>
        </xs:element>
        <xs:element name="Reservation" msprop:Generator_TableClassName="ReservationDataTable" msprop:Generator_TableVarName="tableReservation" msprop:Generator_TablePropName="Reservation" msprop:Generator_RowDeletingName="ReservationRowDeleting" msprop:Generator_UserTableName="Reservation" msprop:Generator_RowChangingName="ReservationRowChanging" msprop:Generator_RowEvHandlerName="ReservationRowChangeEventHandler" msprop:Generator_RowDeletedName="ReservationRowDeleted" msprop:Generator_RowEvArgName="ReservationRowChangeEvent" msprop:Generator_RowChangedName="ReservationRowChanged" msprop:Generator_RowClassName="ReservationRow">
          <xs:complexType>
            <xs:sequence>
              <xs:element name="EventId" msprop:Generator_ColumnVarNameInTable="columnEventId" msprop:Generator_ColumnPropNameInRow="EventId" msprop:Generator_ColumnPropNameInTable="EventIdColumn" msprop:Generator_UserColumnName="EventId" type="xs:int" />
              <xs:element name="SeatId" msprop:Generator_ColumnVarNameInTable="columnSeatId" msprop:Generator_ColumnPropNameInRow="SeatId" msprop:Generator_ColumnPropNameInTable="SeatIdColumn" msprop:Generator_UserColumnName="SeatId" type="xs:int" />
              <xs:element name="CustomerId" msprop:Generator_ColumnVarNameInTable="columnCustomerId" msprop:Generator_ColumnPropNameInRow="CustomerId" msprop:Generator_ColumnPropNameInTable="CustomerIdColumn" msprop:Generator_UserColumnName="CustomerId" type="xs:int" />
            </xs:sequence>
          </xs:complexType>
        </xs:element>
      </xs:choice>
    </xs:complexType>
    <xs:unique name="Constraint1" msdata:PrimaryKey="true">
      <xs:selector xpath=".//mstns:Customer" />
      <xs:field xpath="mstns:CustomerId" />
    </xs:unique>
    <xs:unique name="Event_Constraint1" msdata:ConstraintName="Constraint1" msdata:PrimaryKey="true">
      <xs:selector xpath=".//mstns:Event" />
      <xs:field xpath="mstns:EventId" />
    </xs:unique>
    <xs:unique name="Seat_Constraint1" msdata:ConstraintName="Constraint1" msdata:PrimaryKey="true">
      <xs:selector xpath=".//mstns:Seat" />
      <xs:field xpath="mstns:SeatId" />
    </xs:unique>
    <xs:unique name="Reservation_Constraint1" msdata:ConstraintName="Constraint1" msdata:PrimaryKey="true">
      <xs:selector xpath=".//mstns:Reservation" />
      <xs:field xpath="mstns:EventId" />
      <xs:field xpath="mstns:SeatId" />
    </xs:unique>
    <xs:unique name="Constraint2">
      <xs:selector xpath=".//mstns:Reservation" />
      <xs:field xpath="mstns:EventId" />
    </xs:unique>
    <xs:keyref name="FK_Event_Reservation" refer="Event_Constraint1" msprop:rel_Generator_UserChildTable="Reservation" msprop:rel_Generator_ChildPropName="GetReservationRows" msprop:rel_Generator_ParentPropName="EventRow" msprop:rel_Generator_UserRelationName="FK_Event_Reservation" msprop:rel_Generator_RelationVarName="relationFK_Event_Reservation" msprop:rel_Generator_UserParentTable="Event">
      <xs:selector xpath=".//mstns:Reservation" />
      <xs:field xpath="mstns:EventId" />
    </xs:keyref>
    <xs:keyref name="FK_Seat_Reservation" refer="Seat_Constraint1" msprop:rel_Generator_UserChildTable="Reservation" msprop:rel_Generator_ChildPropName="GetReservationRows" msprop:rel_Generator_ParentPropName="SeatRow" msprop:rel_Generator_UserRelationName="FK_Seat_Reservation" msprop:rel_Generator_RelationVarName="relationFK_Seat_Reservation" msprop:rel_Generator_UserParentTable="Seat">
      <xs:selector xpath=".//mstns:Reservation" />
      <xs:field xpath="mstns:SeatId" />
    </xs:keyref>
    <xs:keyref name="FK_Customer_Reservation" refer="Constraint1" msprop:rel_Generator_UserChildTable="Reservation" msprop:rel_Generator_ChildPropName="GetReservationRows" msprop:rel_Generator_ParentPropName="CustomerRow" msprop:rel_Generator_UserRelationName="FK_Customer_Reservation" msprop:rel_Generator_RelationVarName="relationFK_Customer_Reservation" msprop:rel_Generator_UserParentTable="Customer">
      <xs:selector xpath=".//mstns:Reservation" />
      <xs:field xpath="mstns:CustomerId" />
    </xs:keyref>
  </xs:element>
</xs:schema>

有很多关于如何查询类型化数据表的例子。 请享用！