问题描述
我正在编写一个C＃.NET WinForms应用程序，其中包含两个DataGridView控件，每个控件都有自己的List< DataItem>：¥b $ b $
DataGridView1，List1< DataItem>
DataGridView2，List2< DataItem>
FYI：DataItem是一个由整数，字符串，布尔值等组成的类，以及所有项目每个datagridview控件中列出的列表也列在其相应的List< DataItem>中。
用户将右键单击DataGridView1，然后在结果上下文菜单中单击" ;复制项目"从List1< DataItem>复制DataItem到剪贴板...
$
I'm writing a C# .NET WinForms app which contains two DataGridView controls, each with its own List<DataItem>:
DataGridView1, List1<DataItem>
DataGridView2, List2<DataItem>
FYI: DataItem is a class consisting of integers, strings, booleans, etc., and all items listed in each datagridview control are also listed in its corresponding List<DataItem>.
The user will right-click on a DataGridView1 and in the resulting context menu, click "Copy Item" to copy a DataItem from List1<DataItem> to the clipboard...
private void ctxtContextMenu_ItemClicked(object sender, ToolStripItemClickedEventArgs e)
{
int SelectedRowIndex = DataGridView1.SelectedRows[0].Index;
if (ctxtCopyItem == e.ClickedItem)
{
Clipboard.SetDataObject(List1[SelectedRowIndex]);
}
else if (ctxtPasteItem == e.ClickedItem)
{
PasteDataItem();
}
}
$
b $ b然后用户将转到DataGridView2，右键单击它，然后在上下文菜单中单击"粘贴项目";将DataItem添加到DataGridView2和List2< DataItem> ...
$
The user will then go to DataGridView2, right-click on it and in the context menu, click "Paste Item" to add that DataItem to DataGridView2 and to List2<DataItem>...
private void PasteDataItem()
{
DataItem dataitem = new DataItem();
dataitem = Clipboard.GetDataObject()); // This line is where the error occurs.
List2.Add(dataItem);
UpdateDataGridView2();
}
$
这里是上下文菜单的开放事件处理程序的代码... ...
And here's the code for the context menu's Opening EventHandler...
private void ctxtContextMenu_Opening(object sender, CancelEventArgs e)
{
// If clipboard contains a DataItem, enable ctxtPasteItem...
if (Clipboard.GetDataObject() is DataItem)
ctxPasteQuestion.Enabled = true;
}
$
方法"PasteDataItem（）"上述情况发生异常：
发生System.InvalidCastException
HResult = 0x80004002
Message =无法将类型为'System.Windows.Forms.DataObject'的对象强制转换为'DataItem'。
$
显然，我要么不将DataItem复制到剪贴板正确或我没有正确地从剪贴板中检索它。想到的第一个可能的错误是我需要正确地转换DataItem。我没有找到任何关于
的在线教程，使用剪贴板来复制和粘贴类的实例。这甚至可能吗？
In the method "PasteDataItem()" above, an exception occurs:
System.InvalidCastException occurred
HResult=0x80004002
Message=Unable to cast object of type 'System.Windows.Forms.DataObject' to type 'DataItem'.
Apparently, I'm either not copying DataItem to the clipboard correctly or I'm not retrieving it from the clipboard correctly. The first possible mistake that comes to mind is that I need to cast the DataItem properly. I haven't found any online tutorials on casting, copying and pasting an instance of a class using the clipboard. Is this even possible?
推荐答案
你在哪里提出剪贴板用于传递类/对象在.NET中？
Where did you come up with the clipboard is to be used in passing classes/objects around in .NET?
发生System.InvalidCastException
HResult = 0x80004002
Message =无法将类型为'System.Windows.Forms.DataObject'的对象强制转换为'DataItem'
对象由其蓝图（类）定义。
An object is defined by its blueprint, the class.
如果你看一下每个对象的蓝图，你会发现它们是不同的蓝图。这就像试图拍摄一个马对象并试图制作一个汽车对象。由于蓝图，它不可能发生。
If you look at each object's blueprint, you'll see that they are different blueprints. It's like attempting to take a horse object and trying to make a car object. It can't happen, because of the blueprint.
Java和.NET都是OO平台，OO的原则是相同的。
Both Java and .NET are OO platforms and the principles of OO are the same.
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