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vb.net - 在一个处理程序中处理文本框事件

问题描述

我确实知道如何处理表单中文本框的事件。但是想让这段代码更短。让我在处理程序中停止每次 txtDraw1,2,3,4,5 的写入，并且通常将 txtDraw 的值从 1 到 8。即在包含每个 txtDraw 的句柄中，而不是手动编写它们。

Private Sub TextBoxes_TextChanged(ByVal sender As Object, ByVal e As EventArgs) Handles txtDrawA1.TextChanged, txtDrawA2.TextChanged, txtDrawA3.TextChanged, txtDrawA4.TextChanged, txtDrawA5.TextChanged, txtDrawA6.TextChanged, txtDrawA7.TextChanged, txtDrawA8.TextChanged, txtDrawB1.TextChanged, txtDrawB2.TextChanged, txtDrawB3.TextChanged, txtDrawB4.TextChanged, txtDrawB5.TextChanged, txtDrawB6.TextChanged, txtDrawB7.TextChanged, txtDrawB8.TextChanged, txtDrawC1.TextChanged, txtDrawC2.TextChanged, txtDrawC3.TextChanged, txtDrawC4.TextChanged, txtDrawC5.TextChanged, txtDrawC6.TextChanged, txtDrawC7.TextChanged, txtDrawC8.TextChanged, txtDrawD1.TextChanged, txtDrawD2.TextChanged, txtDrawD3.TextChanged, txtDrawD4.TextChanged, txtDrawD5.TextChanged, txtDrawD6.TextChanged, txtDrawD7.TextChanged, txtDrawD8.TextChanged, txtDrawE1.TextChanged, txtDrawE2.TextChanged, txtDrawE3.TextChanged, txtDrawE4.TextChanged, txtDrawE5.TextChanged, txtDrawE6.TextChanged, txtDrawE7.TextChanged, txtDrawE8.TextChanged, txtDrawF1.TextChanged, txtDrawF2.TextChanged, txtDrawF3.TextChanged, txtDrawF4.TextChanged, txtDrawF5.TextChanged, txtDrawF6.TextChanged, txtDrawF7.TextChanged, txtDrawF8.TextChanged, txtDrawG1.TextChanged, txtDrawG2.TextChanged, txtDrawG3.TextChanged, txtDrawG4.TextChanged, txtDrawG5.TextChanged, txtDrawG6.TextChanged, txtDrawG6.TextChanged, txtDrawG7.TextChanged, txtDrawG8.TextChanged, txtDrawH1.TextChanged, txtDrawH2.TextChanged, txtDrawH3.TextChanged, txtDrawH4.TextChanged, txtDrawH5.TextChanged, txtDrawH6.TextChanged, txtDrawH7.TextChanged, txtDrawH8.TextChanged, txtDrawI1.TextChanged, txtDrawI2.TextChanged, txtDrawI3.TextChanged, txtDrawI4.TextChanged, txtDrawI5.TextChanged, txtDrawI6.TextChanged, txtDrawI7.TextChanged, txtDrawI8.TextChanged
    SetTextBoxColor(DirectCast(sender, TextBox))
End Sub
Sub SetTextBoxColor(ByVal txt As TextBox)
    Select Case txt.Text
        Case "1"
            txt.BackColor = Color.DarkSalmon
        Case "2"
            txt.BackColor = Color.Aqua
        Case "3"
            txt.BackColor = Color.DimGray
        Case "4"
            txt.BackColor = Color.DarkBlue
        Case "5"
            txt.BackColor = Color.Violet
        Case "6"
            txt.BackColor = Color.BlueViolet
        Case "7"
            txt.BackColor = Color.Yellow
    End Select
End Sub

标签： vb.net

解决方案

首先，您不必手动将它们写出来。您可以在设计器中选择多个控件，打开“属性”窗口，单击“事件”按钮，然后双击一个事件，为所有选定控件的该事件生成一个事件处理程序。您还可以使用事件的下拉列表来选择现有处理程序以将一个或多个控件添加到 Handles 子句。

在 VB 中注册事件处理程序有两种方法。您可以使用WithEventsand Handles，这就是您正在做的事情，在这种情况下，您必须在代码中包含每个标识符。这意味着您不能缩短代码并使用Handles子句。子句的替代方法Handles是使用AddHandlerand RemoveHandler。这通常是通过在运行时而不是设计时创建的控件来完成的，但您也可以这样做。在您的情况下，您可以将这样的代码添加到Load表单的事件处理程序中：

Dim letters = {"A", "B", "C", "D", "E", "F", "H", "I"}

For Each letter In letters
    For n = 1 To 8
        AddHandler Controls($"txtDraw{letter}{n}").TextChanged, AddressOf TextBoxes_TextChanged
    Next
Next

您将在FormClosed事件处理程序中执行相同操作，但使用RemoveHandler而不是AddHandler.

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