铸造填充的 List<BaseClass>到列表<ChildClass> [英] Casting populated List&lt;BaseClass&gt; to List&lt;ChildClass&gt;

问题描述

我有一个 List ，里面有成员.我想将列表(特别是它的所有成员)转换为 List 类型，其中 ChildClass 继承 BaseClass.我知道我可以通过 foreach 获得相同的结果:

I have a List<BaseClass> with members in it. I would like to cast the list (and all its members specifically) to a type List<ChildClass>, where ChildClass inherits BaseClass. I know I can get the same result through a foreach:

List<ChildClass> ChildClassList = new List<ChildClass>();
foreach( var item in BaseClassList )
{
    ChildClassList.Add( item as ChildClass );
}

但是有没有更简洁的方法来做到这一点?注意 - 这是在 WP7 平台上完成的.

But is there a neater way of doing this? Note - this is done on the WP7 platform.

推荐答案

如果你真的确定所有项目都是可转换的，你可以这样做:

You can do this if you are really sure all items are castable:

ChildClassList = BaseClassList.Cast<ChildClass>().ToList();

如果 BaseClass 项无法转换为 ChildClass，您当前的代码会添加 null.如果这真的是您的意图，那么这将是等效的:

Your current code adds null if a BaseClass item cannot be cast to ChildClass. If that was really your intention, this would be equivalent:

ChildClassList = BaseClassList.Select(x => x as ChildClass).ToList();

但我更愿意建议这样做，其中包括类型检查并会跳过不匹配的项目:

But i'd rather suggest this, which includes type checking and will skip items that don't match:

ChildClassList = BaseClassList.OfType<ChildClass>().ToList();

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