using System;
using System.Collections;
using System.Collections.Generic;
 
public class Test
{
	public static void Main()
	{
		var xClass = new XClass();
		xClass.Do();
	}
}
 
public class XClass
{
	public List<string> list1 = new List<string>();
 
	public List<string> list2 { get; set; }
 
	public void Do()
	{
		Console.WriteLine("Type = {0}", GetListType(list1));
 
 
		var propertyList = this.GetType().GetProperty("list2"); // i get list from reflection
 
		// Create instance of list2
		var newList = (IList)Activator.CreateInstance((typeof(List<>).MakeGenericType(propertyList.PropertyType))); 
 
		Console.WriteLine("Type = {0}", GetListType(newList));
	}
 
	private Type GetListType(IEnumerable list)
    {
        return list.GetType().GetGenericArguments()[0];
    }
}

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