Question

Consider the ArrayList and LinkedList classes of the standard library.

What abstract class do they extend?

What interface types does that abstract class implement? Draw a class diagram

Answer 1

Both ArrayList and LinkedList are two variants of List which is a dynamic collection of objects.

Both ArrayList and LinkedList extends from the parent class AbstractList<E>

The syntax is

public class ArrayList<E>
   extends AbstractList<E>
   implements List<E>, RandomAccess, Cloneable, Serializable

Here E represents the type of the element to be added in the list.

They implements the the interface called List<E> so that both of ArrayList and LinkedList can use the functions and properties of the List<E> inteface.