AbstractList in Java with Examples

AbstractList in Java is an abstract class in the Java Collections Framework that provides a skeletal implementation of the List interface. It helps developers create custom list implementations by only overriding a few essential methods.

• Provides default implementations for most List methods, reducing coding effort
• Requires overriding core methods like get() and size()
• Improves code reusability when creating custom list classes

Declaration of AbstractList

public abstract class AbstractList<E> extends AbstractCollection<E> implements List<E>

AbstractList is an abstract class, and its main implementations include ArrayList and Vector.

AbstractList: [Geeks, for, Geeks, 10, 20]

Explanation:This program creates an object of a class that extends AbstractList ,adds elements to it using the add() method, and prints the list in insertion order. It demonstrates that AbstractList cannot be instantiated directly but can be used via a subclass.

Hierarchy of AbstractList

Implementation Classes of AbstractList

• ArrayList : Resizable array implementation of List.
• LinkedList : Doubly-linked list implementation supporting sequential access.
• Stack: Last-in-first-out stack extending Vector.
• Vector: Synchronized, resizable array implementation.

Constructor Of AbstractList

protected AbstractList(): Being protected and abstract, you cannot create AbstractList objects directly.

AbstractList<Integer> al = new ArrayList<Integer>();

AbstractList: [Geeks, for, Geeks, 10, 20]
Final AbstractList: [Geeks, for, Geeks, 20]
Last index of A : -1

Methods of AbstractList

Methods declared in class java.util.AbstractCollection

Methods declared in interface java.util.Collection

Methods declared in interface java.util.List