Question

好的，所以我觉得自己很困惑。我正在研究班级库存数据库。我的计划是让一个人在文本框中输入他们的信息和一本书的信息，我希望将这些信息放入lstbox（基本上说谁现在租用这本书）。我还有一个Datagridview，我希望我的txtfile打开并显示书籍，但只有我的txtfile中的对象（Title，Author，ISBN，YearPublishished）。我尝试用查询来做，但它似乎没有工作。

我有一些我需要帮助的错误

当我启动应用程序并单击显示书籍时。我的OFD打开，我单击我需要的txt文件，但它没有正确显示到我的DataGridView。 IT仅显示列中的数字。
我们不得不使用类的对象，我只想知道我是否正确使用它们。这是我第一次这样做，所以任何帮助都会受到赞赏。
我附上了我的申请表

好的，所以我到目前为止：

Public Class Library


Implements IComparable


    'Private Instance Variables - Always declared as Private
    Private m_Title As String
    Private m_Author As String
    Private m_ISBN As String
    Private m_YearPublished As Date
    Private m_DateRented As Date    'use maskedtxtbox for dates and phone number
    Private m_DueDate As Date
    Private m_Name As String
    Private m_Email As String
    Private m_PhoneNumber As String

    Private Shared LibraryCount As Integer

    'Property Blocks for each Private Instance Variable
    Public Property Title() As String
        Get
            Return m_Title
        End Get
        Set(value As String)
            m_Title = value
        End Set
    End Property

    Public Property Author() As String
        Get
            Return m_Author
        End Get
        Set(value As String)
            m_Author = value
        End Set
    End Property

    Public Property ISBN As String
        Get
            Return m_ISBN
        End Get
        Set(value As String)
            m_ISBN = value
        End Set
    End Property
    Public Property YearPublished As Date
        Get
            Return m_YearPublished
        End Get
        Set(value As Date)
            m_YearPublished = value
        End Set
    End Property
    Public Property DateRented As Date
        Get
            Return m_DateRented
        End Get
        Set(value As Date)
            m_DateRented = value
        End Set
    End Property

    Public Property DueDate As Date
        Get
            Return m_DueDate
        End Get
        Set(value As Date)
            m_DueDate = value
        End Set
    End Property



    Public Property Name As String
        Get
            Return m_Name
        End Get
        Set(value As String)
            m_Name = value
        End Set
    End Property

    Public Property Email As String
        Get
            Return m_Email
        End Get
        Set(value As String)
            m_Email = value
        End Set
    End Property

    Public Property PhoneNumber As String
        Get
            Return m_PhoneNumber
        End Get
        Set(value As String)
            m_PhoneNumber = value
        End Set
    End Property


    Public Sub New()
        m_Title = ("")
        m_Author = ""
        m_ISBN = ""
        m_DateRented = ""
        m_DueDate = ""
        m_Name = ""
        m_Email = ""
        m_PhoneNumber = 0
        LibraryCount += 1
    End Sub

    'Overloaded /Parameterized Constructors

    Public Sub New(ByVal p_Title As String, ByVal p_Author As String, ByVal p_ISBN As String, ByVal p_YearPublished As Date,
               ByVal p_DateRented As Date, ByVal p_DueDate As Date, ByVal p_Name As String, ByVal p_Email As String, ByVal p_PhoneNumber As String)
        m_Title = p_Title
        m_Author = p_Author
        m_ISBN = p_ISBN
        m_YearPublished = p_YearPublished
        m_DateRented = p_DateRented
        m_DueDate = p_DueDate
        m_Name = p_Name
        m_Email = p_Email
        m_PhoneNumber = p_PhoneNumber
        LibraryCount += 1
    End Sub


    'QUESTION? How would I calculate when the books is due
    '  Public Function CalcDueDate() As String     'person gets charged if they are late returning the book    

    ' If m_DateRented.Date > m_DueDate.Date Then
    'm_DueDate = m_DateRented + 10
    'MessageBox.Show("You will be charged with a late of .50 cents")
    'End If
    'End Function

    Public Overrides Function ToString() As String
        Return "The user rented a book on" & DateRented & " it will be due on" & DueDate
    End Function

    Public Function CalcDueDate(ByVal p_DueDate As Date) As Date

        Return p_DueDate
    End Function
    Public Function CompareTo(obj As Object) As Integer Implements IComparable.CompareTo

        Throw New NotImplementedException()
        Return m_YearPublished.CompareTo(CType(obj, Library).m_YearPublished)

    End Function

    Public Overrides Function Equals(obj As Object) As Boolean
        'create a library object from the paramer - check to see if it exist
        Dim libraryobj As Library = TryCast(obj, Library)
        If libraryobj Is Nothing Then
            Return False
        Else
            'code for the comparison based on m_yearpublished
            Return m_YearPublished.Equals(libraryobj.m_YearPublished)
        End If
    End Function


End Class

 End Class





Public Class Project1Data

'create counter variable for the array
Dim counter As Integer = 0
'create an array of objects
Private books(12) As Library
'Collection List
Dim mybooklist As New List(Of Library)


Dim abook As Library



Private Sub btnDisplayBooks_Click(sender As Object, e As EventArgs) Handles btnDisplayBooks.Click

    Dim textfile As String
    OpenFileDialog1.ShowDialog()
    textfile = OpenFileDialog1.FileName
    DGVbooks.DataSource = IO.File.ReadAllLines("LibraryDatabase")

End Sub

Public Sub Data()

End Sub
Private Sub btnAdd_Click(sender As Object, e As EventArgs) Handles btnAdd.Click
    'The Btn_Add method creates a Renter and book and adds it to the collectio

    'validate input data
    If ValidateData() = -1 Then
        Exit Sub
    End If

    'use valid input to create an object of the class by calling overloaded constructor
    Dim bookk As New Library(txtbooktitle.Text, txtbookauthor.Text, txtISBN.Text, CDate(txtyearpublished.Text),
                            CDate(txtdaterented.Text), CDate(txtduedate.Text), txtname.Text, txtemail.Text, (txtphonenunber.Text))


    'error check that the array is not full
    If counter >= books.Length Then
        ReDim Preserve books(counter + 1)
    End If

    'add book to the array
    books(counter) = bookk
    'add book to the list
    mybooklist.Add(bookk)

    'increment counter
    counter = counter + 1

    'Notify user that the rental has been recorder
    MessageBox.Show("Rental recorded")

    lstbooksoutput.DataSource = Nothing
    lstbooksoutput.DataSource = books

End Sub

Private Sub Project1Data_Load(sender As Object, e As EventArgs) Handles MyBase.Load
    Dim lines() As String = IO.File.ReadAllLines("LibraryDatabase")


    'In the DGV I just want to display the title, author, isbn, and year published
    ' In the lstbox the user name, email, and phone number will be displayed
    'When a user enters a new book it adds itself to the DGV


    Dim query = From abook In books
                Select abook.Title, abook.Author, abook.ISBN, abook.YearPublished
                Order By abook.YearPublished Ascending
    DGVbooks.DataSource = query.ToList()

好的，我在这里使用重载构造函数创建了一个类的对象，我想我已将它发送到datagridview但它没有显示。

    'Populate a list with Library objects

    With mybooklist
        .Add(New Library("Innoncent Injustice(A Chance Reddick Thriller Book 1), David Archer,B07D6442LM", 2018))
        .Add(New Library("A Breath Of Witchy Air(A Wicked Witches Of the Midwest Mystery), Amanda M Lee, B07CRLRGXH", 2018))
        .Add(New Library("Booke Of the Hidden, Jeri Westerson, 978 - 1635760507", 2017))
        .Add(New Library("Wolves Of Wisteria(Wisteria Witches Mystery), Angela Pepper,978-1719549591", 2018))
        .Add(New Library("Soul Render(Soul Stones Book 1), TL Branson,978-1980871392", 2018))
        .Add(New Library("A Thrift Shop Murder(Cats And Ghosts And Avocado Toasts Book 1), Stanford Pritchard,978-1773480114", 2018))
        .Add(New Library("Cathadeus, Jeff J Peters,B077ZNHY7T", 2017))
        .Add(New Library("Clockwork Alchemist (Thief's Apprenctice Series Book 1), Sara C. Roethle,B01MG26KNA", 2016))
        .Add(New Library("Air Awakens Series, Elise Kova,B01N4A2TK5", 2016))
        .Add(New Library("Keeper of the Dragons The Prince Returns (Keeper of Dragons Book 1), J.A Cullican,B01FYL5BD0", 2016))
        .Add(New Library("Nightblade A Book of UnderRealm, Garrett Robinson,978-1941076309", 2014))
        .Add(New Library("Crazy Rich Asians, Kevin Kwan,B00AP2VQEM", 2013))
        .Add(New Library("Poison Princess (The Arcana Chronicles Book 1), Kresley Cole,978-1442436640", 2012))

    End With

    DGVbooks.DataSource = query.ToList
        DGVbooks.Columns("Title").HeaderText = "Title"
        DGVbooks.Columns("Author").HeaderText = "Author"
        DGVbooks.Columns("ISBN").HeaderText = "ISBN"
        DGVbooks.Columns("Year Publsihed").HeaderText = "Year Published"

        DGVbooks.DataSource = mybooklist
End Sub

Function ValidateData() As Integer
    'This validates the data in all of the textboxes
    'Invalid data returns a -1, else 1
    If txtbooktitle.Text = "" Then
        MessageBox.Show("Please enter a Book Title")
        Return -1
    ElseIf txtbookauthor.Text = "" Then
        MessageBox.Show("Please enter a Book Title")
        Return -1
    ElseIf txtdaterented.Text = "" Or IsNumeric(txtdaterented.Text) = False Then
        MessageBox.Show("Please enter a valid date")
        Return -1
    ElseIf txtduedate.Text = "" Or IsNumeric(txtduedate.Text) = False Then
        MessageBox.Show("Please enter a valid date")
        Return -1
    ElseIf txtyearpublished.Text = "" Or IsNumeric(txtyearpublished.Text) = False Then
        MessageBox.Show("Please enter a valid date")
        Return -1
    ElseIf txtname.Text = "" Then
        MessageBox.Show("Please enter a name")
        Return -1
    ElseIf txtemail.Text = "" Then
        MessageBox.Show("Please enter a valid email")
        Return -1
    ElseIf txtphonenunber.Text = "" Or IsNumeric(txtphonenunber.Text) = False Then
        MessageBox.Show("Please enter a valid phone number")
        Return -1
    Else
        Return 1
    End If

End Function




Private Sub lstbooksoutput_SelectedIndexChanged(sender As Object, e As EventArgs) Handles lstbooksoutput.SelectedIndexChanged
    If lstbooksoutput.SelectedIndex > -1 Then
        Dim intbook As Integer = lstbooksoutput.SelectedIndex
        'get information for that user in the array
        MessageBox.Show(books(intbook).Name & "  has rented" & books(intbook).Title & ".  The book will be due on " & books(intbook).DueDate)

    End If
End Sub


Private Sub btnClear_Click(sender As Object, e As EventArgs) Handles btnClear.Click
    'clear the textboxes
    txtbooktitle.Clear()
    txtbookauthor.Clear()
    txtISBN.Clear()
    txtdaterented.Clear()
    txtduedate.Clear()
    txtyearpublished.Clear()
    txtname.Clear()
    txtemail.Clear()
    txtphonenunber.Clear()

    'reset focus to title box
    txtbooktitle.Focus()
End Sub

结束班

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Answer 1

好的悉尼，让我们开始工作吧！

要么你严重忽略了你的学业，要么你的导师让你挣扎;在这种情况下，你应该通知你的大学，你没有得到你付出的代价。
您的对象包含太多数据。您需要一个书籍对象，一个客户对象和一个租赁对象。假设图书馆馆长想要所有客户的清单。在你的模型中你会得到每个客户列出了很多次，获得导演将是一个烂摊子他的名单。
如果可以，请使用自动属性。我认为它们在VS 2015中可用。您只需要将公共属性标题写为String 而精彩的vb编译器会编写get，set和 Itermedite语言代码中的私有字段。（你赢了在源代码中看到它，但它就在那里）
现在是你的文字档案。每本书一行。本书的每个属性都应该用一个没有出现在其他地方的字符分隔文件。管道符号（|）（大写反斜杠）怎么样所以你文件中的一行看起来像...... 1 | Innoncent Injustice（A. 机会雷迪克惊悚书1）|大卫阿彻| B07D6442LM | 2018通知我添加了另一个字段BookID
我还没有包含默认构造函数（没有参数的构造函数）。这会强制创建书籍对象的任何代码提供所有参数的值，即使它只是＆＃34;＆＃34;。

Public Class Book
    Public Property BookID As Integer
    Public Property Title As String
    Public Property Author As String
    Public Property ISBN As String
    Public Property YearPublished As Integer
    Public Sub New(id As Integer, bTitle As String, bAuthor As String, bISBN As String, bPublished As Integer)
        BookID = id
        Title = bTitle
        Author = bAuthor
        ISBN = bISBN
        YearPublished = bPublished
    End Sub
End Class

Public Class Project1Data
    Private lstBooks As New List(Of Book)
    Private Sub Project1Data_Load(sender As Object, e As EventArgs) Handles MyBase.Load
        Dim textfile As String
        OpenFileDialog1.ShowDialog()
        textfile = OpenFileDialog1.FileName
        Dim lines() As String = IO.File.ReadAllLines(textfile)

        For Each line As String In lines
            Dim fields() As String = line.Split("|"c) 'the little c after "|" indicates that this is a char
            'String.Split takes a char
            Dim b As New Book(CInt(fields(0)), fields(1), fields(2), fields(3), CInt(fields(4)))
            lstBooks.Add(b)
        Next
        DataGridView1.DataSource = lstBooks
    End Sub
End Class

如何使用类的对象填充datagridview

1 个答案: