Vb.net Winforms MDI 多个窗体实例打开

Question

我想知道如何在不重复相同实例的情况下在MDI父窗体中打开多个窗体？例如：License Form和User Form同时打开，不重复。

       For Each f As Form In Application.OpenForms
            If f.Name = "License" Then
                FormOpen = True
                f.Focus()
                Return
            End If

            If f.Name = "User" Then
                FormOpen = True
                f.Focus()
                Return
            End If
        Next

        If FormOpen = False Then
            If e.Node.Name = "License" Then
                Dim license As New License
                license.MdiParent = Me
                license.Show()
            End If


            If e.Node.Name = "User" Then
                Dim license As New User
                license.MdiParent = Me
                license.Show()
            End If
        End If

这是我的代码，但它只能同时打开其中一个表单。有人可以帮忙吗？

Answer 1

使用 Exit statement instead of a Return.

Exit 语句退出过程或块，并立即将控制转移到过程调用或块定义之后的语句。

Return 语句 returns 控制调用 Function、Sub、Get、Set 或 Operator程序。

在这种情况下使用 Exit For。

Answer 2

您可以在模块中声明一个 public 布尔变量，以避免每次打开表单时出现重复。如果您成功打开该变量存储 "True" 值的表单；如果不这样做，它会存储错误。您还必须将 "False" 存储到每个表单的 Closed 事件中的变量。

下面是源码：

Private Sub MDIParent1_Load(sender As Object, e As EventArgs) 句柄 MyBase.Load User.MdiParent = 我 License.MdiParent = 我结束子

Private Sub OpenLicenseAndUserFormsToolStripMenuItem_Click(sender As Object, e As EventArgs) Handles OpenLicenseAndUserFormsToolStripMenuItem.Click
    If bool = True Then
        Exit Sub
    End If
    Try
        For Each f As Form In Me.MdiChildren
            If f.Name = "License" Then
                Dim frm As New License()
                frm.MdiParent = Me
                frm.Show()

            End If

            If f.Name = "User" Then
                Dim frm As New User()
                frm.MdiParent = Me
                frm.Show()

            End If
            bool = True
        Next
    Catch ex As Exception
        MessageBox.Show(ex.Message)
    End Try

End Sub

Vb.net Winforms MDI 多个窗体实例打开

Vb.net Winforms MDI multiple instance of form open

vb.net

forms

mdi