迭代C#中的通用列表

您是否对通用类型V施加约束？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
  where V : Item  //This is a constraint that requires type V to be an Item (or subtype)
{
  public void DoSomething()
  {
    List myList = someMethod();

    foreach (V element in myList)
    {
      //This will now work because you've constrained the generic type V
      Guid test = element.IetmGuid;
    }
  }
}

注意,如果您需要支持多种项目(由Item的子类型表示),则以这种方式使用泛型类是有意义的.

您是否对通用类型V施加约束？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
  where V : Item  //This is a constraint that requires type V to be an Item (or subtype)
{
  public void DoSomething()
  {
    List myList = someMethod();

    foreach (V element in myList)
    {
      //This will now work because you've constrained the generic type V
      Guid test = element.IetmGuid;
    }
  }
}

注意,如果您需要支持多种项目(由Item的子类型表示),则以这种方式使用泛型类是有意义的.