如何测试通用字典对象以查看它是否为空？我想按如下方式运行一些代码:while(reportGraphs.MoveNext()){reportGraph=(ReportGraph)reportGraphs.Current.Value;report.ContainsGraphs=true;break;}reportGraph对象的类型是System.Collections.Generic.Dictionary运行此代码时，reportGraphs字典为空，MoveNext()立即抛出NullReferenceException。如果有更高效的方法来处理空集合，我不想在block周围放置tr