Private Shared fr As New frmName Private Sub ToolBar1_ButtonClick()Sub ToolBar1_ButtonClick(ByVal sender As System.Object, ByVal e As System.Windows.Forms.ToolBarButtonClickEventArgs) Handles ToolBar1.ButtonClick Select Case e.Button.Text Case "OK" ''''"OK" is ToolBarButton.Text If fr Is Nothing Or fr.IsDisposed Then fr = New frmName fr.MdiParent = Me fr.Show() Else fr.MdiParent = Me fr.Show() fr.Focus() End If End Select End Sub
今天又调试了一下,使用了WITH结构,代码如下
Private Shared fr As New frmName Private Sub ToolBar1_ButtonClick()Sub ToolBar1_ButtonClick(ByVal sender As System.Object, ByVal e As System.Windows.Forms.ToolBarButtonClickEventArgs) Handles ToolBar1.ButtonClick Select Case e.Button.Text Case "OK" ''''"OK" is ToolBarButton.Text With fr If fr Is Nothing Or fr.IsDisposed Then fr = New frmName .MdiParent = Me .Show() Else .MdiParent = Me .Show() .Focus() End If End With End Select End Sub
调试出现一错误:Cannot access a disposed object named "frmName".
想了一下,修改了代码,如下 就是把with的范围缩小到fr实例化之后,调试成功~ Private Shared fr As New frmName