泛型List的继承

Question

在.net2.0中 Class A:Class B

List<B> listB as List<A> ListA  不能通过编译器,你们是怎么解决的？

必须将listB 转换为 IList 或者 object ?

Answer 1

lz明明说的是2.0嘛，哪里来的Cast方法？。。。lz可以自行编写一个Cast方法，遍历List<A>，把每个A转换成B，如&nbsp;static IEnumerable<TResult> Cast<TResult>(IEnumerable source) where TResult : class{ &nbsp; &nbsp;foreach (object o in source) &nbsp; &nbsp;{ &nbsp; &nbsp; &nbsp; &nbsp;TResult result = o as TResult; &nbsp; &nbsp; &nbsp; &nbsp;if (o == null) &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;throw new InvalidCastException("can't cast"); &nbsp; &nbsp; &nbsp; &nbsp;yield return result; &nbsp; &nbsp;}}&nbsp;A虽然继承于B，但是List<A>与List<B>并不存在继承关系。&nbsp;

Answer 2

listB.Cast<A>().ToList()