如何测试空的 generic.dictionary 集合？
如何测试通用字典对象以查看它是否为空？我想运行一些代码，如下所示：
while (reportGraphs.MoveNext())
{
reportGraph = (ReportGraph)reportGraphs.Current.Value;
report.ContainsGraphs = true;
break;
}
reportGraph 对象的类型为 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，我不想在块周围放置 try-catch。
谢谢。
How do I test a generic dictionary object to see whether it is empty? I want to run some code as follows:
while (reportGraphs.MoveNext())
{
reportGraph = (ReportGraph)reportGraphs.Current.Value;
report.ContainsGraphs = true;
break;
}
The reportGraph object is of type System.Collections.Generic.Dictionary
When running this code then the reportGraphs dictionary is empty and MoveNext() immediately throws a NullReferenceException. I don't want to put a try-catch around the block if there is a more performant way of handling the empty collection.
Thanks.
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如果它是通用词典，您可以检查 Dictionary.Count< /a>.如果为空，则计数为 0。
但是，就您而言，
reportGraphs看起来像是一个IEnumerator- 您手动枚举集合是否有原因？If it's a generic dictionary, you can just check Dictionary.Count. Count will be 0 if it's empty.
However, in your case,
reportGraphslooks like it's anIEnumerator<T>- is there a reason your enumerating your collection by hand?empty字典和null之间是有区别的。对空集合调用MoveNext不会导致NullReferenceException。我想在你的情况下你可以测试reportGraphs != null。There's a difference between an
emptydictionary andnull. CallingMoveNexton an empty collection won't result in aNullReferenceException. I guess in your case you could test ifreportGraphs != null.