Question

I require a fast speed in processing my page. The count of the values to be added will be dynamic.

Which one of the above is preferred? Support with a valid reason.

Edit: For eg:

string str = "a,b,c"; //Count of the number of elements in str is not fixed
string[] arr = str.Split(',');

or,

ArrayList al = new ArrayList();
al.Add(str.Split(','));

Answer 1

List<T> should generally be preferred over ArrayList

• faster for value types as it avoids boxing.
• strongly typed elements

If you want lists you expose to callers to be immutable, this is supported by both List<T> and ArrayList:

List<T>.AsReadOnly()
ArrayList.ReadOnly(ArrayList list);

Your question asks about choosing between ArrayList and List<T>, but your example shows an array, which is neither.