所有我想做的是检查一个对象是否为null,但无论我做什么,如果它编译,它抛出一个NullReferenceException只是试图检查!这里是我做了:
If ((Not (comp.Container Is Nothing)) And (Not (comp.Container.Components Is Nothing))) Then For i As Integer = 0 To comp.Container.Components.Count() - 1 Step 1 fixUIIn(comp.Container.Components.Item(i),style) Next End If If ((Not IsDBNull(comp.Container)) And (Not IsDBNull(comp.Container.Components))) Then For i As Integer = 0 To comp.Container.Components.Count() - 1 Step 1 fixUIIn(comp.Container.Components.Item(i),style) Next End If If ((Not IsNothing(comp.Container)) And (Not IsNothing(comp.Container.Components))) Then For i As Integer = 0 To comp.Container.Components.Count() - 1 Step 1 fixUIIn(comp.Container.Components.Item(i),style) Next End If If ((Not (comp.Container Is DBNull.Value)) And (Not (comp.Container.Components Is DBNull.Value))) Then For i As Integer = 0 To comp.Container.Components.Count() Step 1 fixUIIn(comp.Container.Components.Item(i),style) Next End If
我看过VB书,搜索几个论坛,和一切应该工作不是!对不起,问这样的补救问题,但我只是需要知道。
只是这样你知道,调试器说,null对象是comp.Container