在 C# 中迭代泛型列表
声明：本页面是StackOverFlow热门问题的中英对照翻译，遵循CC BY-SA 4.0协议，如果您需要使用它，必须同样遵循CC BY-SA许可，注明原文地址和作者信息，同时你必须将它归于原作者（不是我）：StackOverFlow
原文地址: http://stackoverflow.com/questions/284220/
Warning: these are provided under cc-by-sa 4.0 license. You are free to use/share it, But you must attribute it to the original authors (not me):
StackOverFlow
Iterate though Generic List in C#
提问by
public class Item
{
private int _rowID;
private Guid _itemGUID;
public Item() { }
public int Rid
{
get
{
return _rowID;
}
set { }
}
public Guid IetmGuid
{
get
{
return _itemGuid;
}
set
{
_itemGuid= value;
}
}
}
The above is my custom object.
以上是我的自定义对象。
I have a list:
我有一个清单：
List<V> myList = someMethod;
where V is of type Item, my object.
其中 V 的类型为 Item，即我的对象。
I want to iterate and get the properties as such
我想迭代并获取这样的属性
foreach(V element in mylist)
{
Guid test = element.IetmGuid;
}
When I debug and look at the 'element' object I can see all the properties in the 'Quickwatch' but I cannot do element.IetmGuid.
当我调试并查看“元素”对象时，我可以看到“Quickwatch”中的所有属性，但我无法执行 element.IetmGuid。
回答by TcKs
foreach( object element in myList ) {
Item itm = element as Item;
if ( null == itm ) { continue; }
Guid test = itm.ItemGuid;
}
回答by user34292
Your list should be declared like this:
你的列表应该这样声明：
List<V> myList = someMethod;
Where V is the type item.
其中 V 是类型项。
and then your iteration was correct:
然后你的迭代是正确的：
foreach(V element in myList)
{
Guid test = element.IetmGuid;
}
回答by Daniel M
Try declaring your list like this:
尝试像这样声明你的列表：
List<Item> myList = someMethod;
回答by akmad
Are you putting a constraint on the generic type V? You'll need to tell the runtime that V can be any type that is a subtype of your Itemtype.
您是否对泛型 V 施加了限制？您需要告诉运行时 V 可以是您的Item类型的子类型的任何类型。
public class MyGenericClass<V>
where V : Item //This is a constraint that requires type V to be an Item (or subtype)
{
public void DoSomething()
{
List<V> myList = someMethod();
foreach (V element in myList)
{
//This will now work because you've constrained the generic type V
Guid test = element.IetmGuid;
}
}
}
Note, it only makes sense to use a generic class in this manner if you need to support multiple kinds of Items (represented by subtypes of Item).
请注意，只有当您需要支持多种 Item（由 Item 的子类型表示）时，以这种方式使用泛型类才有意义。
