Question

我在一个具有多种形式的项目中。

我在这里创建一个TicTacToe表单：

 Private Sub MenuTicTacToe(ByVal sender As Object, ByVal e As System.EventArgs)
    Dim page As Form = New TicTacToe
    page.Show(Me)
End Sub

这是一个TicTacToe表单：

Public Class TicTacToe

    Public opponent as String
    'Some code where user set opponent

    Public Function Receive(S As String)
    if string = opponent
        'Some code
    End Function

End Class

我想以我的主要形式调用函数Receive 如果我这样做：

TicTactoe.Receive（S）它会在没有对手的情况下调用Receive的实例。

我想找到TicTacToe的对应形式并致电Receive

谢谢

Answer 1

在线评论

Private Sub Button2_Click(sender As Object, e As EventArgs) Handles Button2.Click
    page.Receive("Joe")
End Sub
'A form level variable to hold a reference to the instance of TicTacToe
'Although vb.net can use default instances, you have created an explicit
'instance of TicTacToe so you need to keep a reference if you want to
'refer to this instance.
Private page As TicTacToe
Private Sub MenuTicTacToe(ByVal sender As Object, ByVal e As System.EventArgs)
    page = New TicTacToe()
    page.Show(Me)
End Sub

Partial Public Class TicTacToe
    Inherits Form
    Public opponent As String
    'Functions must be declared as a Type
    'If you do not need a return value use a Sub
    Public Function Receive(S As String) As String
        Dim someString As String = ""
        If S = opponent Then
            'Do something
        End If
        'There must be a return Value
        Return someString
    End Function

End Class

Answer 2

使用它来显示表单

Dim page As TicTacToe
Private Sub MenuTicTacToe(ByVal sender As Object, ByVal e As System.EventArgs)
    page = New TicTacToe
    page.Show(Me)
End Sub

然后您就可以使用

page.Receive(S)

修改

使用多种形式

For Each f As TicTacToe in Application.OpenForms().OfType(Of TicTacToe)
        f.Receive (S)
Next

Answer 3

在C＃中，您将需要一个新实例，但是就像在VB中一样，编译器已经为您完成了此操作。

您当前正在做的是创建TicTacToe表单的新实例并显示它：

Private Sub MenuTicTacToe(ByVal sender As Object, ByVal e As System.EventArgs)
    Dim page As Form = New TicTacToe
    page.Show(Me)
End Sub

但是您不会在任何地方保存该实例。然后，在下一段代码中，您将使用另一个实例，该实例是由编译器创建的静态实例：

TicTacToe.Receive(S) // TicTacToe is the static instance

因此，您最终要调用两个不同的实例，这说明了为什么没有设置对手的原因。

要解决此问题，请不要创建新实例。在您的Private Sub MenuTicTacToe中，只需使用由编译器创建的实例，就不会出现此问题，就像这样：

Private Sub MenuTicTacToe(ByVal sender As Object, ByVal e As System.EventArgs)
    TicTacToe.Show(Me)
End Sub

希望这会有所帮助。

VB-从父级查找子级表单

3 个答案: