未將對象引用設置爲對象的實例。 Visual Basic中的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

在Java

相同的代碼是this link 未將對象引用設置爲對象的實例。 Visual Basic中的VB

來源

2013-02-23 binit92

請注意，您的數組的大小將是族羣大小+ 1，因爲在VB中的數組聲明傳遞的值是上限，不尺寸。 – 2013-02-25 16:30:48

它已經有一段時間，我已經做了VB，但我認爲你語句來在New - 方法創建一個新的局部變量tours隱藏的全局變量tours。

試試這個：

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

來源

2013-02-23 12:29:32 Koen

嘗試，

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

來源

2013-02-23 12:53:47 Nalaka526

未將對象引用設置爲對象的實例。 Visual Basic中的VB

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