每次离开并重新进入类时,Visual Basic都会将我的变量重置为0

Question

我有一张表格可以从用户那里获得财务信息,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.任何帮助都是极好的.

这是我的表格中的代码:

    '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

这个代码来自关联类:

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

请尝试这样做,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