Question

在我的代码中，我有4个按钮。我的“搜索按钮”（按钮2）和我的“查看数据按钮”（按钮4）出现问题。我一直在收到我似乎无法解决的错误。我只是想知道是否有人能够帮助我。先感谢您。详细信息写在代码之间，这样你就可以看到我遇到问题的地方。

 Imports System.IO
Public Class Form1

    Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
        Dim pInventory As IO.StreamWriter = IO.File.AppendText("product.txt")
        If TextBox1.Text = "" Or TextBox2.Text = "" Or TextBox3.Text = "" Then
            MsgBox("Please fill in required fields", MsgBoxStyle.Exclamation, "Error")
        Else
            pInventory.WriteLine(TextBox1.Text & ", $" & TextBox2.Text & ", " & TextBox3.Text)
            TextBox1.Clear()
            TextBox2.Clear()
            TextBox3.Clear()
            Dim num As Integer
            For num = 0 To ListBox1.Items.Count - 1
                pInventory.WriteLine(ListBox1.Items(num))
            Next
            pInventory.Close()
        End If
    End Sub

'此处我无法搜索在数据条目中输入/保存的产品 '它告诉我异常未得到处理。它说它是一个无效的论点

Private Sub Button2_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button2.Click
        Dim name As String
        Dim num As Integer
        Dim max As Integer
        name = InputBox("What item would you like to search for :", "Product Search")
        num = 0
        max = ListBox1.Items.Count - 1

问题在这里（num）

 Do While (name <> (ListBox1.Items.Item(num))) And (num < max)
        num = num + 1

        ListBox1.Items.Add(num)
    Loop
    If (name = ListBox1.Items.Item(num)) Then
        MsgBox(name & " Was found", , "Search")
    Else
        MsgBox(name & " Was not found", , "Search")
    End If
End Sub
Private Sub Button3_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button3.Click
    If ListBox1.SelectedIndex <> -1 Then
        ListBox1.Items.RemoveAt(ListBox1.SelectedIndex)
    Else
        MsgBox("Please make a selection")
    End If
End Sub

'在这里，当你点击button4（“查看数据”）按钮时，我只想让存档显示在数据输入中输入的所有内容 '但我似乎无法将其显示在只显示数据的位置，而不是要求您输入存档名称 “我想我刚刚用这个项目搞定了！”

Private Sub Button4_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button4.Click
 Dim item As String
        Dim product As StreamReader
        item = InputBox("Please enter archive name", "Product List")
        item = item & ".txt"
        If File.Exists(item) Then
            product = File.OpenText(item)
            ListBox1.Items.Clear()
            Do While product.Peek <> -1
                ListBox1.Items.Add(product.ReadLine)
            Loop
            product.Close()
        Else
            MsgBox("Archive does not exist!", MsgBoxStyle.Critical, "Error")
        End If
    End Sub
End Class

Answer 1

Do While (name <> (ListBox1.Items.Item(num))) And (num < max)

在上面的代码中，如果您的ListBox不包含任何项目ListBox1.Items.Item(num)将触发异常， ArgumentOutOfRangeException 。您可以添加条件以确保ListBox1包含一些项目：

Do While (ListBox1.Items.Count > 0 AndAlso name <> (ListBox1.Items.Item(num))) And (num < max)

单击Button4，您要显示文件中的所有数据而不询问文件名？如果是这种情况，您可以在模块级别声明的全局常量中对文件名进行硬编码，然后您可以在需要时从该常量中获取文件名，例如：

Public Const ArchieveName As String = "Product.txt"
...

item = ArchieveName

您也在Button1点击事件上对文件名进行了硬编码。

我只需要在我的代码中“搜索”和“显示数据”的提示。任何提示？

1 个答案: