Vb.net 通用。位图列表无法添加新位图
由于NullReferenceException,无法添加新位图。这是什么原因Vb.net 通用。位图列表无法添加新位图,vb.net,bitmap,generic-list,Vb.net,Bitmap,Generic List,由于NullReferenceException,无法添加新位图。这是什么原因 Dim bitmap As Bitmap = New Bitmap(10, 10) Dim listbitmap As List(Of Bitmap) Dim rand As Random Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click Fo
Dim bitmap As Bitmap = New Bitmap(10, 10)
Dim listbitmap As List(Of Bitmap)
Dim rand As Random
Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
For x As Integer = 0 To 9
For y As Integer = 0 To 9
bitmap.SetPixel(x, y, Color.Black)
Next y
Next x
PictureBox1.Image = bitmap
Me.Refresh()
listbitmap.Add(New Bitmap(bitmap)) 'error starts here
End Sub
你忘了
listbimat=new List(Of Bitmap)
(Dim listbimat As List(Of Bitmap)
只是定义了类型,它不构建新对象)@Jimi它在第2行中没有新的(有点押韵:)你也可以写:私有listbimat作为新列表(Of Bitmap)
。注意你是如何在第一行创建一个新的位图来创建一个这种类型的新对象的?如果不创建对象,对象就不存在。与此类似,如果您需要该类型的新对象,则需要创建一个新列表(位图)
。rand
变量也是如此,即它是Nothing
,除非实际创建类型为Random
的对象并将其分配给该变量。