Property of a Property of an Object

[tora]

Hello, I'm posting in hopes of someone being able to help me figure out what I'm doing wrong in the following code

Public Class HouseAddress
    Public Property HouseNumber As Integer
    Public Property StreetName As String

    Private Sub Init()
        HouseNumber = 0
        StreetName = "TEST ST"
    End Sub
End Class

Public Class Person
    Public Property Name As String
    Public Property Location As HouseAddress

    Private Sub Init()
        Name = "Test Name"
        Location = new HouseAddress()
    End Sub
End Class

and within the main app:

Class Window1
    Dim Tora as Person

    Private Sub Init()
        Tora = new Person()
        Debug.WriteLine(Tora.Name)
        Try
            Debug.WriteLine(Tora.Location.StreetName)
        Catch ex As Exception
            Debug.WriteLine("Error=" + ex.Message)
        End Try
    End Sub
End Class

And the output I'm getting is:
"Test Name"
"Error=Object reference not set to an instance of an object"

I understand the error is saying I've got a null pointer reference happening, but I don't understand why. Anyone smarter than me able to help?

Thanks a lot!!

 

[jmcilhinney]

In your last code snippet, you create a Person object but you never call its Init method, so a HouseAddress object is never created or assigned to its Location property. I think maybe you are under the misconception that your Init methods are constructors. They aren't. A constructor is always named New. Change the name of the Init method in the Person class to New and it will be invoked automatically when you create a New Person.

 

[tora]

Holy Smokes! Thank you. You were exactly right, I thought the Init() methods were the constructors, changed to New() and all is right with the world. Thanks a lot!