Type List vs type ArrayList in Java

Question

(1) List<?> myList = new ArrayList<?>(); (2) ArrayList<?> myList = new ArrayList<?>();

I know that with (1) the implementations of the List interface can be swapped. It seems that (1) is typically used in applications regardless of need (I always use this myself).

Does anyone use (2)?

Also, how often does the situation actually require using (1) over (2) [i.e., where (2) wouldn't suffice..aside coding to interfaces and best practices, etc.]?

Please explain with an example

Answer 1

The list is preferred over ArrayList because List can be translated into a LinkedList without affecting the remaining codebase.

For example, you have decided LinkedList is better to use for your application, but later you have decided ArrayList might be a better considering performance reason.

Use:

List list = new ArrayList(100); //  also better to set the initial capacity of a collection 

Instead of:

ArrayList list = new ArrayList();

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