GridView ChechBox check all in vb.net

[sushil349]

I am getting error as Object reference not set to an instance of an object.
Exception Details: System.NullReferenceException: Object reference not set to an instance of an object.

Source Error:


Line 251: ' .FindControl("chk"), CheckBox)
Line 252: If chk IsNot Nothing Then
Line 253: chk.Checked = arr.Contains(gvAll.DataKeys(i).Value)
Line 254:
Line 255: If Not chk.Checked Then
please help me

 Private Sub GetData()
        Dim arr As ArrayList
        If ViewState("SelectedRecords") IsNot Nothing Then
            arr = DirectCast(ViewState("SelectedRecords"), ArrayList)
        Else
            arr = New ArrayList()
        End If
        Dim chkAll As CheckBox = DirectCast(gvAll.HeaderRow _
                    .Cells(0).FindControl("chkAll"), CheckBox)
        For i As Integer = 0 To gvAll.Rows.Count - 1
            If chkAll.Checked Then
                If Not arr.Contains(gvAll.DataKeys(i).Value) Then
                    arr.Add(gvAll.DataKeys(i).Value)
                End If
            Else
                Dim chk As CheckBox = DirectCast(gvAll.Rows(i).Cells(0) _
                                            .FindControl("chk"), CheckBox)
                If chk.Checked Then
                    If Not arr.Contains(gvAll.DataKeys(i).Value) Then
                        arr.Add(gvAll.DataKeys(i).Value)
                    End If
                Else
                    If arr.Contains(gvAll.DataKeys(i).Value) Then
                        arr.Remove(gvAll.DataKeys(i).Value)
                    End If
                End If
            End If
        Next
        ViewState("SelectedRecords") = arr
    End Sub
 
    Private Sub SetData()
        Dim i As Integer
        Dim var = DirectCast(ViewState("SelectedRecords") _
                                        , ArrayList)
        ' Dim s = DirectCast(ViewState("SelectedRecords") _
        '   , ArrayList)
        Dim currentCount As Integer = 0
        Dim chkAll As CheckBox = DirectCast(gvAll.HeaderRow _
                        .Cells(0).FindControl("chkAll"), CheckBox)
        chkAll.Checked = True
        Dim arr As ArrayList = DirectCast(ViewState("SelectedRecords") _
                                        , ArrayList)
 
        For i = 0 To gvAll.Rows.Count - 1
 
            Dim chk As CheckBox = DirectCast(gvAll.Rows(i).Cells(0) _
                                            .FindControl("chk"), CheckBox)
            'Dim var = DirectCast(gvAll.Rows(i).Cells(0) _
            ' .FindControl("chk"), CheckBox)
            If chk IsNot Nothing Then
                chk.Checked = arr.Contains(gvAll.DataKeys(i).Value)
 
                If Not chk.Checked Then
                    chkAll.Checked = False
                Else
                    currentCount += 1
                End If
            End If
        Next
        hfCount.Value = (arr.Count - currentCount).ToString()
    End Sub

[Frinavale]

Could be that the Cells property is nothing... Try using the FindControl method on the row instead:

  Dim chk As CheckBox = DirectCast(gvAll.Rows(i).FindControl("chk"), CheckBox)
 
  If chk IsNot Nothing Then
    chk.Checked = arr.Contains(gvAll.DataKeys(i).Value)
    If Not chk.Checked Then
      chkAll.Checked = False
    Else
      currentCount += 1
    End If
  End If

-Frinny