怪异的VB.net向其他窗体显示文本行为

大家好，我有一个程序，我想把我的form1的文本显示到我的form3中，其中form2有执行命令的按钮，调试中没有错误，但是当我点击我的form2中的按钮时，我想要的form1中的form3上的数据不在那里。请帮我，伙计们，提前谢谢

表格1代码：

 Public Class Form1
Private frm2 As Form2
Private Sub Button3_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button3.Click

    If frm2 Is Nothing Then
        frm2 = New Form2
        AddHandler frm2.FormClosed, AddressOf Me.Form2HasBeenClosed

        Dim Label21 As Label = New Label
        frm2.Label21.Text = TextBox1.Text
        frm2.Label21.ForeColor = Color.Black
     End If

    If frm2 IsNot Nothing Then
        frm2.Show(Me) 'Show Second Form  
        Me.Hide()
    End If

End Sub

表格2代码：

Public Class Form2
Private frm1 As New Form1
Private frm3 As Form3
Public lbl As New Label
    Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click


    Dim Label21 As Label = New Label
    Dim Textbox1 As TextBox = New TextBox
    frm3.Label21.Text = frm1.TextBox1.Text

        Form3.Show()


End Sub
End Class

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您需要将Form1实例的引用传递给名为frm2的Form2实例。 当在Form2类代码中尝试显示Form3时，应使用该引用传递Form1初始实例中的值。相反，您的代码构建Form1 Form1 frm=new Form1的新实例，并尝试从此实例获取值。当然，作为Form1的新实例，frm1变量不包含原始实例中存在的任何值

Public Class Form2
    Private frm1 As Form1   ' remove the new here because it creates a new instance of Form1'
    Private frm3 As Form3
    Public lbl As New Label ' not needed?'

    ' add a constructor that receives the instance of the caller'
    Public Sub New(callerInstance as Form1)

        ' Call required if you add your constructor manually'
        InitializeComponent()

        ' save the instance of the Me variable passed to this constructor'
        frm1 = callerInstance
    End Sub

    Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click

       ' Dim Label21 As Label = New Label          ' this label is not needed'
       ' Dim Textbox1 As TextBox = New TextBox     ' this  textbox is not needed'

       ' Create a new instance of Form3, do not use the automatic Form3 instance
       ' automatically created by VB.NET 
       frm3 = new Form3()

       ' now you are referring to the caller instance of Form1 '
       ' where there is the textbox filled with your text '
       frm3.Label21.Text = frm1.TextBox1.Text
       frm3.Show()

     End Sub
End Class

然后更改Fomr1类中以这种方式构建Form2实例的代码

Private Sub Button3_Click(...........)

    If frm2 Is Nothing Then
        frm2 = New Form2(Me)
        .....

此更改使用Form1 Me的当前实例调用在Form2的类代码中定义的构造函数，并且正是此实例包含稍后需要传递给frm3的文本框值

我不想光顾这里，但似乎您对类和类实例有点困惑。您需要很好地理解这一点，因为它是面向对象编程的基本支柱之一。VB自动创建表单对象在这里没有帮助

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这里有一个非常基本的介绍：

先生，感谢您的帮助..我有一个问题Private Sub-NewcallerInstance，因为Form1在调试时犯了一个错误，我试图找出它，但我无法即时通讯，只是编程方面的新手，请帮助我，谢谢错误是在设计器生成的类型中警告2“Private Sub-NewcallerInstance as Form1”“WindowsApplication1.Form2”应调用InitializeComponent方法。先生抱歉，此指南不清楚，请帮助我如何通过代码合并初始化组件非常感谢先生许多感谢先生steve先生是的，它解决了问题，但出现了另一个问题错误1“WindowsApplication1.Form2.Private Sub NewcallerInstance As”“Form1”在此上下文中不可访问，因为它是“Private”。它在我的Form1上出错您好，先生。它创建了另一个错误错误1参数，未为“Public Sub NewcallerInstance As Form1”的参数“callerInstance”指定。感谢您，我已使用这些评论中出现的详细信息修改了答案。现在对未来的过路人来说也应该没问题