CODEWITHSUNDEEP
vb.netvisual-studio-2010genetic-algorithm
binit92
binit92

Reputation: 95

Object reference not set to an instance of an object. visual basic vb

Public Class Population

 Dim tours() As Tour    ' Tour is a class and I have to make and object array

 Public Sub New(ByVal populationSize As Integer, ByVal initialise As Boolean)

    Dim tours As New Tour(populationSize)   ' 

    If initialise Then
        ' Loop and create individuals
        For i As Integer = 0 To (populationSize - 1)
            Dim newTour As New Tour()
            newTour.generateIndividual()
            saveTour(i, newTour)
        Next i
    End If
End Sub

Public Sub saveTour(ByVal index As Integer, ByVal tour As Tour)
    tours(index) = tour           ' getting error in this line 
End Sub

same code in java is in this link

Upvotes: 0

Views: 1267

Answers (2)

Nalaka526
Nalaka526

Reputation: 11484

Try, 

Public Sub New(ByVal populationSize As Integer, ByVal initialise As Boolean)

    ReDim tours(populationSize)

    If initialise Then
        ' Loop and create individuals
        For i As Integer = 0 To (populationSize - 1)
            Dim newTour As New Tour()
            newTour.generateIndividual()
            saveTour(i, newTour)
        Next i
    End If
End Sub

Upvotes: 1

Koen
Koen

Reputation: 2571

It's been a while that I've done VB but I think your DIM-statement in the New-method creates a new local variable tours that hides the global variable tours.

Try this:

Public Class Population

 Dim tours() As Tour

 Public Sub New(ByVal populationSize As Integer, ByVal initialise As Boolean)

    tours = New Tour(populationSize)   ' 

    If initialise Then
        ' Loop and create individuals
        For i As Integer = 0 To (populationSize - 1)
            Dim newTour As New Tour()
            newTour.generateIndividual()
            saveTour(i, newTour)
        Next i
    End If
End Sub

Public Sub saveTour(ByVal index As Integer, ByVal tour As Tour)
    tours(index) = tour 
End Sub

Upvotes: 2

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