VB.NET：如何确定接收值的目标子窗体（避免静态索引）

方法一：按窗体类型精准查找 #

遍历MDI父窗体的子窗体集合，筛选出目标类型的窗体实例，不受其他无关子窗体影响。

' 遍历查找目标TrackerPV窗体
Dim targetForm As TrackerPV = Nothing
For Each childForm As Form In Me.MdiParent.MdiChildren
    If TypeOf childForm Is TrackerPV Then
        targetForm = DirectCast(childForm, TrackerPV)
        Exit For
    End If
Next

' 找到后执行传值逻辑
If targetForm IsNot Nothing Then
    targetForm.ReceiveValue(cbDecision.SelectedItem.ToString)
Else
    MessageBox.Show("TrackerPV窗体未打开")
End If

注：如果存在多个同类型子窗体，可额外判断窗体标题、Tag等属性来精准定位。

方法二：通过唯一标识定位 #

给目标窗体设置唯一标识（比如Tag属性），遍历集合时匹配标识，适合同类型多实例场景。

1. 先在TrackerPV窗体的初始化逻辑中设置标识：

' 在TrackerPV的Load事件或构造函数中设置
Me.Tag = "TargetTrackerPV"

2. 在发送方窗体中查找：

Dim targetForm As TrackerPV = Nothing
For Each childForm As Form In Me.MdiParent.MdiChildren
    If childForm.Tag IsNot Nothing AndAlso childForm.Tag.ToString() = "TargetTrackerPV" AndAlso TypeOf childForm Is TrackerPV Then
        targetForm = DirectCast(childForm, TrackerPV)
        Exit For
    End If
Next

' 传值逻辑同上
If targetForm IsNot Nothing Then
    targetForm.ReceiveValue(cbDecision.SelectedItem.ToString)
End If

方法三：在MDI父窗体维护子窗体引用 #

在父窗体中直接保存目标子窗体的实例引用，子窗体通过父窗体直接访问，无需遍历集合。

1. MDI父窗体中声明公共属性：

' 父窗体类内声明
Public Property TrackerPVInstance As TrackerPV
Public Property TrackerNRInstance As TrackerNR

' 打开TrackerPV时赋值
Dim pvForm As New TrackerPV()
pvForm.MdiParent = Me
Me.TrackerPVInstance = pvForm
pvForm.Show()

2. 发送方子窗体（TrackerNR）中调用：

' 强制转换为父窗体类型
Dim parentForm As YourMdiParentClass = DirectCast(Me.MdiParent, YourMdiParentClass)

' 检查实例是否存在且未被释放
If parentForm.TrackerPVInstance IsNot Nothing AndAlso Not parentForm.TrackerPVInstance.IsDisposed Then
    parentForm.TrackerPVInstance.ReceiveValue(cbDecision.SelectedItem.ToString)
End If

内容的提问来源于stack exchange，提问作者JeffyO