Question

我有一张表格可以从用户那里获取财务信息，包括贷款金额，费率和期限。我应该打电话给一个班级来完成这项工作，然后将答案返回给表格。但是，出于某种原因，每当我的程序移出类，返回表单，然后返回类，我将类重置为0的变量。我的代码如下。任何帮助都会很棒。

这是我表单中的代码：

    'Preform calculation when button is clicked
Private Sub buttonCalc_Click(sender As Object, e As EventArgs) Handles buttonCalc.Click
    Dim loanAmount As New finClass
    Dim rate As New finClass
    Dim term As New finClass
    Dim payment As New finClass
    loanAmount.getLoanAmount = textBoxMortgageAmount.Text
    rate.getAnnualRate = comboBoxAnnualRate.Text.Replace("%", "")
    term.getTermInYears = comboBoxTerm.SelectedItem
    textBoxMonthlyPayment.Text = payment.setMonthlyPayment

End Sub

来自关联类的代码：

Public Class finClass

Private loanAmt As Decimal
Private termValue As Decimal
Private rateValue As Decimal
Public paymentValue As Decimal

Public WriteOnly Property getLoanAmount
    Set(value)
        If IsNumeric(value) AndAlso value > 1000 AndAlso value < 10000000 Then
            Me.loanAmt = value
        Else
            MessageBox.Show("Mortgage amount must be a number between $1,000 and $10,000,000", "Invalid Number", MessageBoxButtons.OK, MessageBoxIcon.Error)
        End If
    End Set
End Property

Public WriteOnly Property getAnnualRate
    Set(value)
        rateValue = value.Replace("%", "")
        If rateValue < 1 Then
            rateValue *= 100
        End If

    End Set
End Property

Public WriteOnly Property getTermInYears
    Set(value)
        termValue = value
    End Set
End Property

Public ReadOnly Property setMonthlyPayment
    Get
        Return -Pmt((rateValue / 1200), termValue * 12, Me.loanAmt)
    End Get
End Property
End Class

Answer 1

我不在VS中工作，但看起来你正在创建该类的四个实例。我很确定这不正确。

Private Sub buttonCalc_Click(sender As Object, e As EventArgs) Handles buttonCalc.Click
    Dim loanAmount As New finClass  '## Creates NEW finClass object
    Dim rate As New finClass        '## Creates NEW finClass object
    Dim term As New finClass        '## Creates NEW finClass object
    Dim payment As New finClass     '## Creates NEW finClass object
    loanAmount.getLoanAmount = textBoxMortgageAmount.Text
    rate.getAnnualRate = comboBoxAnnualRate.Text.Replace("%", "")
    term.getTermInYears = comboBoxTerm.SelectedItem
    textBoxMonthlyPayment.Text = payment.setMonthlyPayment

End Sub

因此，每个对象都是finClass对象的不同实例。因此，每次“重新进入”该类时，您实际上都会进入该类对象的不同的实例，这就是为什么所有变量都是值= 0.它们尚未实例化或设置，然而。

尝试这样做，创建一个类对象，您可以使用类模块中的方法进行操作：

Private Sub buttonCalc_Click(sender As Object, e As EventArgs) Handles buttonCalc.Click
    Dim objFinClass as New finClass

    objFinClass.getLoanAmount = textBoxMortgageAmount.Text
    objFinClass.getAnnualRate = comboBoxAnnualRate.Text.Replace("%", "")
    objFinClass.getTermInYears = comboBoxTerm.SelectedItem
    textBoxMonthlyPayment.Text = objFinClass.setMonthlyPayment

End Sub

Answer 2

创建一个模块并使用＆＃39; Public＆＃39;标量变量公共模块示例公共ExampleVariable为Integer 结束模块

只要程序正在运行，这将允许变量保留其值。在表单类中使用dim将导致每次加载表单时重新定义值

每次离开并重新进入类时，Visual Basic都会将我的变量重置为0

2 个答案: