将绑定列表转换为通用列表<T>

Question

I need to convert a bound (UnityEngine.Component) List to a generic (T) List, is this possible? how?

I'm using Unity and C#, but I would like to know in general how one would do this.

        List<Component> compList = new List<Component>();
        foreach(GameObject obj in objects)   // objects is List<GameObject>
        {
            var retrievedComp = obj.GetComponent(typeof(T));
            if(retrievedComp != null)
                compList.Add(retrievedComp);
        }

        List<T> newList = new List<T>(compList as IEnumerable<T>); // ERROR HERE

        foreach(T n in newList)
            Debug.Log(n);

thanks!

I assume that is the issue, I'm getting this runtime error...

ArgumentNullException: Argument cannot be null.
Parameter name: collection
System.Collections.Generic.List`1[TestPopulateClass].CheckCollection (IEnumerable`1 collection)
System.Collections.Generic.List`1[TestPopulateClass]..ctor (IEnumerable`1 collection)
DoPopulate.AddObjectsToList[TestPopulate] (System.Reflection.FieldInfo target) (at Assets/Editor/ListPopulate/DoPopulate.cs:201)
System.Reflection.MonoMethod.Invoke (System.Object obj, BindingFlags invokeAttr, System.Reflection.Binder binder, System.Object[] parameters, System.Globalization.CultureInfo culture)
Rethrow as TargetInvocationException: Exception has been thrown by the target of an invocation.
System.Reflection.MonoMethod.Invoke (System.Object obj, BindingFlags invokeAttr, System.Reflection.Binder binder, System.Object[] parameters, System.Globalization.CultureInfo culture)
System.Reflection.MethodBase.Invoke (System.Object obj, System.Object[] parameters)
DoPopulate.OnGUI () (at Assets/Editor/ListPopulate/DoPopulate.cs:150)
System.Reflection.MonoMethod.Invoke (System.Object obj, BindingFlags invokeAttr, System.Reflection.Binder binder, System.Object[] parameters, System.Globalization.CultureInfo culture)

Answer 1

你有没有尝试过

    List<T> newList = compList.OfType<T>().Select(x=>x).ToList()

Answer 2

Most likley cased by the fact that T and Component are different types: List<Component> compList and compList as IEnumerable<T> (this one will be null since compList is IEnumerable<Component> not IEnumerable<T> ).

I think you want:

    List<T> compList = new List<T>(); // +++ T instead of GameObject
    foreach(GameObject obj in objects)   // objects is List<GameObject> 
    { 
        // ++++ explict cast to T if GetComponent does not return T
        var retrievedComp = (T)obj.GetComponent(typeof(T)); 
        if(retrievedComp != null) 
            compList.Add(retrievedComp); 
    } 

    List<T> newList = new List<T>(compList as IEnumerable<T>); // ERROR HERE 

    foreach(T n in newList) 
        Debug.Log(n);