以编程方式创建简单的加法表单应用程序

Question

我想在表单应用程序中创建一个简单的加法程序 vb.net。我还想以编程方式创建所有控件。我有三个文本框和一个按钮。当按钮被单击时，它从两个文本框中获取值，并将其分配给第三个文本框的值。 我无法从按钮单击句柄获取文本框字符串。

我的编码如下：

Public Class Form1
Public Sub Form1_Load(sender As Object, e As EventArgs) Handles MyBase.Load
'Pushbutton
Dim PushButton As New Button()
PushButton.Text = "Add"
PushButton.Location = New Point(10, 100)
Me.Controls.Add(PushButton)
AddHandler PushButton.Click, AddressOf myButtonHandler_Click
'
'TextBox1
Dim TextBox1 As New TextBox
TextBox1.Location = New Point(10, 3)
Me.Controls.Add(TextBox1)
'TextBox2
Dim TextBox2 As New TextBox
TextBox2.Location = New Point(200, 3)
Me.Controls.Add(TextBox2)

Dim TextBox3 As New TextBox
TextBox3.Location = New Point(200, 100)
Me.Controls.Add(TextBox3)
End Sub
Private Sub myButtonHandler_Click(ByVal sender As Object, ByVal e As EventArgs)
End Sub
Public Function ADD(x As Double, y As Double) As Double
ADD = x + y
End Function
End Class

Answer 1

通过将控件的声明移动到窗体级别，可以在窗体的所有方法中看到它们。

Public Class Form3
Private TextBox1 As New TextBox
Private TextBox2 As New TextBox
Private TextBox3 As New TextBox
Private PushButton As New Button
Private Sub Form3_Load(sender As Object, e As EventArgs) Handles MyBase.Load
'Pushbutton
PushButton.Text = "Add"
PushButton.Location = New Point(10, 100)
Me.Controls.Add(PushButton)
AddHandler PushButton.Click, AddressOf myButtonHandler_Click
'TextBox1
TextBox1.Location = New Point(10, 3)
Controls.Add(TextBox1)
'TextBox2
TextBox2.Location = New Point(200, 3)
Controls.Add(TextBox2)
'TextBox3
TextBox3.Location = New Point(200, 100)
Controls.Add(TextBox3)
End Sub
Private Sub myButtonHandler_Click(ByVal sender As Object, ByVal e As EventArgs)
Dim firstNumber = CDbl(TextBox1.Text)
Dim secondNumber = CDbl(TextBox2.Text)
TextBox3.Text = ADD(firstNumber, secondNumber).ToString
End Sub
Public Function ADD(x As Double, y As Double) As Double
ADD = x + y
End Function
End Class

Answer 2

从技术上讲，您可以按原样执行此操作，但前提是对按钮单击事件使用匿名事件处理程序，如下所示：

Public Class Form1
Public Sub Form1_Load(sender As Object, e As EventArgs) Handles MyBase.Load
'TextBox1
Dim TextBox1 As New TextBox
TextBox1.Location = New Point(10, 3)
Me.Controls.Add(TextBox1)
'TextBox2
Dim TextBox2 As New TextBox
TextBox2.Location = New Point(200, 3)
Me.Controls.Add(TextBox2)
Dim TextBox3 As New TextBox
TextBox3.Location = New Point(200, 100)
Me.Controls.Add(TextBox3)
'Pushbutton
Dim PushButton As New Button()
PushButton.Text = "Add"
PushButton.Location = New Point(10, 100)
Me.Controls.Add(PushButton)
AddHandler PushButton.Click, Sub()
Dim dblA, dblB As Double
If Double.TryParse(TextBox1.Text, dblA) AndAlso Double.TryParse(TextBox2.Text, dblB) Then
TextBox3.Text = ADD(dblA, dblB)
Else
MessageBox.Show("One or more Invalid Inputs")
End If
End Sub
End Sub
Public Function ADD(x As Double, y As Double) As Double
ADD = x + y
End Function
End Class

尽管我确实建议按照 Mary 的建议将这些控件声明移到窗体级别。