如何将带有streamwriter的文本附加到文本文件中？

问题描述

我正在构建我的第一个应用程序（使用.vb），这是一个日历约会应用程序。我以这种方式创建了它 - 我有三个文本框，每个文本框用于日期，时间和位置。文本框中的文本条目将发送到列表框。在列表框中，我有一个保存按钮，用于将条目保存为文件夹中的文本文件。我有一个show appointmentments按钮来加载文本文件。我的问题是，当我创建一个新约会时，文本文件中的上一个条目被覆盖，所以我需要将列表框中的新条目附加到保存约会的文本文件中。



我尝试过：



这是保存按钮的代码。

 Private Sub Button3_Click（sender As Object，e As EventArgs）处理Button3.Click 
 IO.Directory.CreateDirectory（C：\ Test）
 Dim w As New IO.StreamWriter（C：\ Test \ 01.txt）
 Dim i As Integer 
 
 For i = 0 To ListBox1.Items.Count  -  1 
 w .WriteLine（ListBox1.Items.Item（i））
下一个
 w.Close（）
 End Sub 

这是整个应用程序代码。

 Public Class Form1 
 Private Sub Button1_Click（sender As Object，e As EventArgs）Handles Button1.Click 
 ListBox1.Items.Add（TextBox1.Text）
 ListBox1.Items.Add（Te xtBox2.Text）
 ListBox1.Items.Add（TextBox3.Text）
 End Sub 
 
 Private Sub Button2_Click（sender As Object，e As EventArgs）处理Button2.Click 
 ListBox1.Items.RemoveAt（ListBox1.SelectedIndex（））
 End Sub 
 
 Private Sub ListBox1_SelectedIndexChanged（sender As Object，e As EventArgs）处理ListBox1.SelectedIndexChanged，ListBox1.Click 
 
 
 End Sub 
 
 Private Sub Button3_Click（sender As Object，e As EventArgs）处理Button3.Click 
 IO.Directory.CreateDirectory（C：\\ \\ Test）
 Dim w As New IO.StreamWriter（C：\Test\01.txt）
 Dim i As Integer 
 
 For i = 0 To ListBox1.Items.Count  -  1 
 w.WriteLine（ListBox1.Items.Item（i））
 Next 
 w.Close（）
 End Sub 
 
 Private Sub Button4_Click（发送者作为对象，e作为EventArgs）处理Button4.Click 
 Dim r作为IO.StreamReader 
r =新的IO.StreamReader（C：\ Test \ 01.txt）
 while（r.Peek（）> -1）
 ListBox1.Items.Add（r.ReadLine）
 End 
 r.Close（）
 End Sub 
 
 Private Sub Button5_Click（ sender As Object，e As EventArgs）处理Button5.Click 
 Me.TextBox1.Text = Me.DateTimePicker1.Text 
 
 End Sub 
 End Class 

解决方案

I'm building my first application (using .vb), which is a calendar appointment app. I've created it in this manner - I have three textboxes, one each for date, time and location. The text entries from the textboxes are sent to a list box. At the listbox, I have a save button to save the entries as an appointment to a text file in a folder. I have a show appointments button to load the text file. My problem is that when I create a new appointment, the previous entry on the text file is overwritten, so I need to append the new entries in the list box to the text file saving the appointments.

What I have tried:

This is the code for the save button.

Private Sub Button3_Click(sender As Object, e As EventArgs) Handles Button3.Click
        IO.Directory.CreateDirectory("C:\Test")
        Dim w As New IO.StreamWriter("C:\Test\01.txt")
        Dim i As Integer

        For i = 0 To ListBox1.Items.Count - 1
            w.WriteLine(ListBox1.Items.Item(i))
        Next
        w.Close()
    End Sub

This is the entire app code.

Public Class Form1
    Private Sub Button1_Click(sender As Object, e As EventArgs) Handles Button1.Click
        ListBox1.Items.Add(TextBox1.Text)
        ListBox1.Items.Add(TextBox2.Text)
        ListBox1.Items.Add(TextBox3.Text)
    End Sub

    Private Sub Button2_Click(sender As Object, e As EventArgs) Handles Button2.Click
        ListBox1.Items.RemoveAt(ListBox1.SelectedIndex())
    End Sub

    Private Sub ListBox1_SelectedIndexChanged(sender As Object, e As EventArgs) Handles ListBox1.SelectedIndexChanged, ListBox1.Click


    End Sub

    Private Sub Button3_Click(sender As Object, e As EventArgs) Handles Button3.Click
        IO.Directory.CreateDirectory("C:\Test")
        Dim w As New IO.StreamWriter("C:\Test\01.txt")
        Dim i As Integer

        For i = 0 To ListBox1.Items.Count - 1
            w.WriteLine(ListBox1.Items.Item(i))
        Next
        w.Close()
    End Sub

    Private Sub Button4_Click(sender As Object, e As EventArgs) Handles Button4.Click
        Dim r As IO.StreamReader
        r = New IO.StreamReader("C: \Test\01.txt")
        While (r.Peek() > -1)
            ListBox1.Items.Add(r.ReadLine)
        End While
        r.Close()
    End Sub

    Private Sub Button5_Click(sender As Object, e As EventArgs) Handles Button5.Click
        Me.TextBox1.Text = Me.DateTimePicker1.Text

    End Sub
End Class

解决方案

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