引用非共享成员需要 showing/hiding 表单的对象引用

Question

我有 3 个表单，form2 包含一些我想在 form3 的数据网格视图中显示的信息，我在网上搜索了如何操作，所以不是很精通或完全理解这些变化和或者我写的代码，只要它有效。现在的问题是来自其他表单 1 和 2 的按钮应该隐藏和/或显示其他表单，但有错误，这是一个项目，非常感谢您的帮助，谢谢。

form1（错误 1，粗体）

Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles 
gin.Click
    Dim nun As String = "apple"
    Dim pw As Single = 7

    
    Dim name As String
    
    Dim wd As Double
   

    name = name.Text
    wd = word.Text
   
    If (name = nun And wd = pw) Then
        Me.Hide()
        **try**.Show() ' error here
    Else
        
        MsgBox("Denied", vbOKOnly + MsgBoxStyle.Critical, "TRY AGAIN")       End If

End Sub

form2（数据网格视图代码）

Private Sub btnSave_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles 
    Save.Click

    view.dgvView.CurrentRow.Cells(1).Value = Id.Text
    view.dgvView.CurrentRow.Cells(2).Value = fruit.Text
    view.dgvView.CurrentRow.Cells(3).Value = veggie.Text
    view.dgvView.CurrentRow.Cells(4).Value = pasta.Text
    view.dgvView.CurrentRow.Cells(5).Value = drink.Text
End Sub

表3（其中错误2，粗体部分和上面的代码是我看不懂的代码）

Public Class sky
    Private Sub dgvView_CellContentClick(ByVal sender As System.Object, ByVal e As 
    System.Windows.Forms.DataGridViewCellEventArgs) Handles sky.CellContentClick
        If e.ColumnIndex = 1 Then
            Dim entry As New sky(Me)
            entry.ShowInTaskbar = False
            entry.ShowDialog()
        End If
    End Sub

    Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles blue.Click
        Me.Close()
        **sky**.Show()

    End Sub
End Class

Answer 1

frmEntry 不是一个变量，它是一个类型（一个 class 名称）。您可以使用 Dim entry As New frmEntry(Me) 创建的变量 entry 来访问表单对象。但是由于这个变量是一个局部变量，它只能在声明它的 Sub 内部访问。在 class 级别（在 Sub 之外）声明它，以便其他 Sub 可以访问它。

Public Class frmView
    Dim entry As frmEntry ' <===== declare here

    Private Sub FirstSub()
        entry = New frmEntry(Me)  ' <==== Create and assign here
        entry.ShowInTaskbar = False
        entry.Show()
    End Sub

    Private Sub SecondSub()
        entry.Close() ' <=== Reference it from somewhere else
    End Sub
End Class

请注意，class（因此也是表单）是引用类型。除了像 Integer 这样的值类型，引用类型的变量不存储分配给它的对象，而是对该对象的引用。查看区别：

Dim a, b As Integer
Dim f1, f2 As frmTest

a = 5
b = a
b = 10
' Now a = 5 and b = 10

f1 = new frmTest()
f1.Text = "Test 1"
f2 = f1
f2.Text = "Test 2"
' Now f1.Text = "Test 2" and f2.Text = "Test 2" because there is only one Form
' object referenced by the two variables.

引用非共享成员需要 showing/hiding 表单的对象引用

Reference to a non-shared member requires an object reference for showing/hiding forms

vb.net

winforms