Question

Imports System.IO
Imports System

Public Class Form1

    Private Class movie
        Public name As String
        Public actors() As String
        Public year As String
        Public country As String
        Public votes As String

    End Class

    Private movies(0) As movie
    Private fs As FileStream
    Private input As StreamReader

    Private Sub LoadToolStripMenuItem_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles LoadToolStripMenuItem.Click
        OpenFileDialog1.ShowDialog()
        Dim i As Integer = 0

        Dim currentmv As New movie
        Dim reader As String()


        If File.Exists(OpenFileDialog1.FileName) Then

            lblPath.Text = OpenFileDialog1.FileName
            Dim iFile As New StreamReader(lblPath.Text)

            While Not iFile.EndOfStream

                reader = iFile.ReadLine.Split(";")

                currentmv.name = reader(0)
                currentmv.actors = reader(1).Split(",")
                currentmv.year = reader(2)
                currentmv.country = reader(3)
                currentmv.votes = reader(4)

                lbMovies.Items.Add(currentmv.name)

                movies(i) = currentmv

                i = i + 1
                ReDim movies(i)

            End While
        End If

    End Sub

    Private Sub lbMovies_SelectedIndexChanged(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles lbMovies.SelectedIndexChanged
        Dim i As Integer

        For i = 0 To movies(lbMovies.SelectedIndex).actors.Length

            lbActors.Items.Add(movies(lbMovies.SelectedIndex).actors(i))

        Next

    End Sub
End Class

Problem strikes when I request the length. It says it’s a null reference, but I cannot see any mistake in this. Is there an issue when I request the length of the array in an array of objects?

Answer 1

Try

ReDim Preserve movies(i)

IIRC ReDim will initialize all elements to Nothing without Preserve.