How do I check if a List contains an object of a certain type? C#

问题

I have a list (called Within), and it contains objects of type GameObject. GameObject is a parent class to many others, including Dog and Ball. I want to make a method that returns true if Within contains any object of type Ball, but I don't know how to do this.

I've tried using Count<>, Any<>, Find<> and a few other methods provided within C#, but I couldn't get them to work.

public bool DetectBall(List<GameObject> Within)
{
    //if Within contains any object of type ball:
    {
        return true;
    }
}

回答1:

if (within.OfType<Ball>().Any())

The generic parameter of all LINQ methods except Cast<T>() and OfType<T>() is used to allow the method call to compile and must be compatible with the type of the list (or for a covariant cast). They cannot be used to filter by type.

回答2:

in non-linq if you're interested

public bool DetectBall(List<GameObject> Within)
{
    foreach(GameObject go in Within)
    {
        if(go is Ball) return true;
    }

    return false;
}

来源：https://stackoverflow.com/questions/8216881/how-do-i-check-if-a-list-contains-an-object-of-a-certain-type-c-sharp