VS2019 Throw new gives excpetion

[lamko]

I'm following the book Visual Basic 2012 How to Program
I've created a very simple class :

Public Class Form1
    Dim First As Employee = New Employee
    Dim Second As Employee = New Employee
    Private Sub Form1_Load(sender As Object, e As EventArgs) Handles MyBase.Load
        First.FirstName = "John"
        First.LastName = "Henderson"
        First.MonthlySalary = 0

        MessageBox.Show(First.MonthlySalary * 12 & " Year income")
        MessageBox.Show((First.MonthlySalary * 12) * 1.1 & " Year income with 10 % raise")

        Second.firstname = "Billy"
        Second.lastname = "The Kid"
        Second.MonthlySalary = 1500

        MessageBox.Show(Second.MonthlySalary * 12 & " Year income")
        MessageBox.Show((Second.MonthlySalary * 12) * 1.1 & " Year income with 10 % raise")
    End Sub
End Class

Public Class Employee
    Private _FirstName As String
    Private _LastName As String
    Private _MonthlySalary As Integer

    Public Sub New()
        _FirstName = "test"
        _LastName = "test"
        _MonthlySalary = 1
    End Sub

    Public Property FirstName As String
        Get
            Return _FirstName
        End Get
        Set(value As String)
            _FirstName = value
        End Set
    End Property

    Public Property LastName As String
        Get
            Return _LastName
        End Get
        Set(value As String)
            _LastName = value
        End Set
    End Property

    Public Property MonthlySalary As Integer
        Get
            Return _MonthlySalary
        End Get
        Set(value As Integer)
            If value <= 0 Then
                Throw New ArgumentOutOfRangeException("positive") '<_-------this one
            End If
            _MonthlySalary = value
        End Set
    End Property
End Class

If I delete the line with the comment <-- this one I get "0 year income", as expected.
But with the line I should get "positive" But I get this error message seen below :


Here is the exercise question :
9.7 (Employee Class) Create a class called Employee that includes three pieces of information as
instance variables—a first name (type String), a last name (type String) and a monthly salary (type
Integer). Your class should have a constructor that initializes the three instance variables. Provide
a property for each instance variable. The property for the monthly salary should ensure that its value remains positive—if an attempt is made to assign a negative value, throw an exception. Write an
app that demonstrates class Employee’s capabilities. Create two Employee objects and display each
object’s yearly salary. Then give each Employee a 10% raise and display each Employee’s yearly salary
again.

Is it a bug in Visual Studio don't think so. But my book explains it so it should work!
Shed some light on this one you guys !

[jmcilhinney]

This is a perfect example of why you should ALWAYS read the documentation for new types and members, ESPECIALLY when they don't work as expected. You could have got the same information by simply paying attention to Intellisense as you typed but the documentation is more thorough. There's really no excuse for not doing so, given that you can simply click a type or member in VS and press F1 to be taken directly to the relevant documentation.

If you had done that then you would know that the constructor with a single String parameter expects the name of the parameter whose value was out of range. You have no parameter named positive in that context so how can that be an appropriate argument to pass to that constructor? If you want to pass an actual error message to the constructor then you have to use one of the overloads that takes an error message as an argument. I'm not going to point out which those are because you can find out for yourself by reading the documentation.

What I will say is that, in this case, you ought to use the overload that also allows you to pass in the actual value and you should also provide a sensible error message. "positive" doesn't qualify. In line with the sort of messages usually received in such cases, it should be something like "The value must be greater than 0." or "The value must be greater than or equal to 0.". Note that the assignment is bad because it says that the salary must be positive and must not be negative but it doesn't mention whether zero is allowed or not. This is an example of sloppy thinking on the part of whoever wrote the assignment and something you should avoid as a developer. If you fail to consider all the possible scenarios then, when one you haven't considered arises, your app will either crash or, even worse, carry on in an unknown state that could lead to data corruption or incorrect output.

[lamko]

Lets consider one thing a read the documentation about throw but there was a total lack of information on the Microsoft site.
I've tried everything just a simple Throw New ArgumentOutOfRangeException() isnt working !

Or
Throw New ArgumentOutOfRangeException("value", "message")

[sapator]

I don't usually bash people like JMC does (no offense intended there JMC) but it looks like you refuse to read the documentation as he said in the previous post.
If you read this then you would know that you need to capture the exception
https://docs.microsoft.com/en-us/dot...n?view=net-5.0

  Dim c As New Employee
        Try
            c.MonthlySalary = -1
        Catch ex As ArgumentOutOfRangeException

        End Try

Having said that, it's not a good idea to throw exceptions when they are not absolutely necessary as they tend to slow performance.
You can easily handle this by doing and IF .MonthlySalary < 0 before you set the value.

[lamko]

I was in the assumption that a Throw New was enough. But I had to look better, my mistake.
Thx guys