Why assign a new ArrayList to a List variable?

Question

I am new to java and when I go through the code of many examples on net I see people declaring the variable for an ArrayList as simply List in almost all the cases.

List<String> myList = new ArrayList<String>();

I don't understand if there is some specific advantage of doing this. Why can't it be an ArrayList itself, like so:

ArrayList<String> myList = new ArrayList<String>();

Answer 1

It's called programming to an interface. It allows you to substitute that ArrayList for a LinkedList if somewhere down the line you decide that a LinkedList would be more appropriate.