如何将 List<T> 转换为 T 的派生类 [重复]

Question

AnswerRecords返回DnsRecordBase的列表：

List<DnsRecordBase> _Records = _DnsMessage.AnswerRecords;

MxRecord 继承自 DnsRecordBase：

public class MxRecord : DnsRecordBase

如何投_Records有MxRecord的列表？

我试过了：

List<MxRecord> _Records = (MxRecord)_DnsMessage.AnswerRecords;
List<MxRecord> _Records = _DnsMessage.AnswerRecords as MxRecord;

这种语法不起作用:)

Answer 1

如果_Records 中的所有元素都是MxRecord，这应该可以工作

List<DnsRecordBase> _Records = _DnsMessage.AnswerRecords;
List<MxRecord> _MxRecords = _Records.Cast<MxRecord>().ToList();