如何在关闭之前从对话框表单访问属性，VB.NET winforms [英] How do I access a property from a dialog form before it gets closed, VB.NET winforms

问题描述

希望你们所有人都很好并且进入2018年。



我会把它分解成一些简单的项目的术语描述起来很复杂，所以这里是基础知识。



Form1创建一个新的Form2实例并将其显示为showdialog - 我无法访问List声明从Form2到Form1。



我不能有全局声明或变量 - 下面进一步解释。



我尝试过：



我有两种形式，都是在设计师中创建的。

Form1创建表格2的新实例/副本通过

 Dim NewForm As New Form2 
 NewForm.ShowDialog（）

我正在使用showdialog但是我很乐意使用show show但这给了我一组新的问题，就是从Form2中找到，那个叫Form，即创建Form2的新实例/副本，已关闭。



项目将包含更多的表单，即Form3，Form4，Form5 .... Form20，都创建了Form2的新副本，需要从Form2访问List（of String）的副本，因此全局声明List（of String）是不可能的。



那些调用Form2的表单也可以通过新的表单命令从其他表单创建。因此，通过变量来跟踪该表单是否已关闭对我来说是不利的。



在Form2上，我有一些数据存储在

 List（Of String）

在Form2中，我已经在课堂上声明：

 Dim _Keywords As New List（Of String）
 
 Friend ReadOnly Property Keywords（）As List（Of String）
获取
返回_关键词
结束获取
 
结束物业
 

我需要访问（来自Form1,3,4,5,6 ...... 20）Form2上的List（Of String）才能处理/关闭/设置为空，而不是任何更快。



目前我在showdialog之后在Form1中执行此操作：

 Dim Kwords As List（Of String）= GlobalFind.Keywords 
 NewFrm.Dispose 
 NewFrm = Nothing 

$ 1 $ b在Form1中，Kwords列出它总是空的，当我看时，我得到一个数= 0。希望有意义，谢谢你给我你的时间（希望我忽略了一个解决方案）。

解决方案

在Form2上公开一个属性，然后得到结果Form1：



Form2

 公共 类 Form2 
 
 私有 mResults 正如列表（>  字符串）
 公开 属性结果（）作为列表（ Of  字符串）
 获取 
 返回 mResults 
 结束 获取 
 设置（ ByVal 值作为列表（  字符串））
 mResults = value 
 结束 设置 
 结束 属性 
 
 私有  Sub  butSave_Click（sender 作为 对象，e 作为 EventArgs）句柄但保留。点击
 
 ' 在此处设置结果 
结果= 新列表（   String ）来自{  111，  222，< span class =code-string>  333} 
 
关闭（）
 
 结束  Sub  
 
 结束 班级 

Form1

 公开 类 Form1 
 
 私有  Sub  Button1_Click（发件人 As   Object ，e  As  EventArgs） Handles  Button1.Click 
 
  Dim  NewForm  As  新 Form2 
 NewForm.ShowDialog（）
 
  Dim 结果 As  List（  字符串）= NewForm.Results 
 
  End   Sub  
 
 结束 类 

Hi,
Hope all of you are well and settling into 2018 :)

I'll break this down into some simple terms as the project is quite complicated to describe, so here's the basics.

Form1 creates a new instance of Form2 and shows it as showdialog - I cannot access the List declaration from Form2, into Form1.

I cannot have global declarations or variables - explained further, below.

What I have tried:

I have two forms, both created in the designer.
Form1 creates a new instance/copy of Form 2 via

Dim NewForm As New Form2
                NewForm.ShowDialog()

I am using showdialog but I am happy to use just show but that gives me a new set of problems, which is to find out from Form2, that calling Form, that is creating a new instance/copy of Form2, has been closed.

The project will contain many more forms i.e. Form3, Form4, Form5....Form20, all creating a new copy of Form2 and need to access "that copy of List(of String)" from Form2, so a global declaration of the List(of String) is not possible.

Those calling forms, to Form2 - may also be created via a new form command, from other forms. So keeping track via variables of whether that form has been closed, is no good to me.

On Form2, I have some data that I am storing in a

List(Of String)

In Form2, I have declared at the top of the class:

Dim _Keywords As New List(Of String)

   Friend ReadOnly Property Keywords() As List(Of String)
       Get
           Return _Keywords
       End Get

   End Property

I need to access (from Form1 ,3,4,5,6....20) the List(Of String) on Form2 before it gets disposed/closed/set to nothing and not any sooner.

At the moment I do this in Form1 after the showdialog:

 Dim Kwords As List(Of String) = GlobalFind.Keywords
NewFrm.Dispose
NewFrm=Nothing

in Form1, Kwords list its always empty, I get a count=0 when I look. Hope that makes sense and Thank you for giving me your time (and hopefully a solution I have overlooked).

解决方案

Expose a property on Form2, then get the results in Form1:

Form2

Public Class Form2

    Private mResults As List(Of String)
    Public Property Results() As List(Of String)
        Get
            Return mResults
        End Get
        Set(ByVal value As List(Of String))
            mResults = value
        End Set
    End Property

    Private Sub butSave_Click(sender As Object, e As EventArgs) Handles butSave.Click

        ' set results here
        Results = New List(Of String) From {"111", "222", "333"}

        Close()

    End Sub

End Class

Form1

Public Class Form1

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

        Dim NewForm As New Form2
        NewForm.ShowDialog()

        Dim results As List(Of String) = NewForm.Results

    End Sub

End Class

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