如何将List <t>转换为T </t>的派生类

Question

AnswerRecords返回DnsRecordBase的列表：

List<DnsRecordBase> _Records = _DnsMessage.AnswerRecords;

MxRecord继承自DnsRecordBase：

public class MxRecord : DnsRecordBase

如何投标_Records有一个MxRecord列表？

我试过了：

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

此语法不起作用：）

Answer 1

如果_Records中的所有元素都是MxRecord

，这应该有用

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