C# generic list <T> how to get the type of T?
c#, generic-list, reflection
Solution
Type type = pi.PropertyType;
if(type.IsGenericType && type.GetGenericTypeDefinition()
== typeof(List<>))
{
Type itemType = type.GetGenericArguments()[0]; // use this...
}
More generally, to support any `IList<T>`, you need to check the interfaces:
foreach (Type interfaceType in type.GetInterfaces())
{
if (interfaceType.IsGenericType &&
interfaceType.GetGenericTypeDefinition()
== typeof(IList<>))
{
Type itemType = type.GetGenericArguments()[0];
// do something...
break;
}
}
Problem
I'm working on a reflection project, and now I'm stuck. If I have an object of `myclass` that can hold a `List<SomeClass>`, does anyone know how to get the type as in the code below if the property `myclass.SomList` is empty? ``` List<myclass> myList = dataGenerator.getMyClasses(); lbxObjects.ItemsSource = myList; lbxObjects.SelectionChanged += lbxObjects_SelectionChanged; private void lbxObjects_SelectionChanged(object sender, SelectionChangedEventArgs e) { Reflect(); } Private void Reflect() { foreach (PropertyInfo pi in lbxObjects.SelectedItem.GetType().GetProperties()) { switch (pi.PropertyType.Name.ToLower()) { case "list`1": { // This works if the List<T> contains one or more elements. Type tTemp = GetGenericType(pi.GetValue(lbxObjects.SelectedItem, null)); // but how is it possible to get the Type if the value is null? // I need to be able to create a new object of the type the generic list expect. // Type type = pi.getType?? // how to get the Type of the class inside List<T>? break; } } } } private Type GetGenericType(object obj) { if (obj != null) { Type t = obj.GetType(); if (t.IsGenericType) { Type[] at = t.GetGenericArguments(); t = at.First<Type>(); } return t; } else { return null; } } ```