VB.Net/Development/Exception System

Parse Number Exception

Imports System
Public Class MainClass
    
    Shared Sub Main(ByVal args As String())
        Dim num_items As Integer
        Try
            num_items = Integer.Parse("aa")
        Catch ex As Exception
            Console.WriteLine("Error in Num Items." & vbCrLf & ex.Message)
            Exit Sub
        End Try
        " Check that the value is between 1 and 100.
        If num_items < 1 Or num_items > 100 Then
            Console.WriteLine("Num Items must be between 1 and 100")
            Exit Sub
        End If
    End Sub
End Class

Use Argument Exception

Imports System
Imports System.Collections
Public Class MainClass
    
    Shared Sub Main(ByVal args As String())
        Try
            Dim rect As New DrawableRectangle(10, 20, 0, -100)
        Catch ex As Exception
            Console.WriteLine(ex.Message)
        End Try
    End Sub
End Class
Public Class DrawableRectangle
    Public Sub New(ByVal new_x As Integer, ByVal new_y As Integer, ByVal new_width As Integer, ByVal new_height As Integer)
        " Verify that new_width > 0.
        If new_width <= 0 Then
            " Throw an ArgumentException.
            Dim ex As New ArgumentException( _
                "DrawableRectangle must have a width greater than zero", _
                    "new_width")
            Throw ex
        End If
        " Verify that new_height> 0.
        If new_height <= 0 Then
            " Throw an ArgumentException.
            Throw New ArgumentException( _
                "DrawableRectangle must have a height greater than zero", _
                    "new_height")
        End If
    End Sub
End Class