ArrayList and LinkedList Class in Java Framework

Collection Classes

There are various classes available in Collection Framework that implements Collection interfaces. These are given below.

ArrayList Class

ArrayList class is used to store the array element dynamically. The ArrayList class extends the AbstarctList class and implements the List interface.

Properties of ArrayList

In ArrayList, duplicate objects are allowed in index order.
ArrayList class preserves the insertion order.
ArrayList allows null insertion.
The null insertion is possible in ArrayList and more than one null value can be allowed.
The ArrayList object is not thread-safe, means non-synchronized.
The ArrayList object work at the index basis.

Example : Program to add, retrieve, and remove element from ArrayList

import java.util.*;
public class ArrayListDemo
{
      public static void main(String args[])
      {
            ArrayList<String> al = new ArrayList<String>();
            System.out.println("Initial size of ArrayList: "+al.size());

            // add element to the ArrayList
            al.add("Mango");
            al.add("Banana");
            al.add("Orange");
            al.add("Papaya");
            al.add("Mango");
            System.out.println("ArrayList elements after addition: "+al);
            System.out.println("Size of ArrayList:"+al.size());

            // Remove the 5th indes elemenrt
            al.remove(4);
            System.out.println("ArrayList elements after deletion: "+al);

            //Remove Banana
            al.remove("Banana");
            System.out.println("ArrayList elements after deletion: "+al);
            System.out.println("Size of ArrayList after deletion: "+al.size());

            //Retriving 2nd index element
            String al1 = (String)(al.get(2));
            System.out.println("The element at 2nd index is: "+al1);
      }
}

Output:
Initial size of ArrayList: 0
ArrayList elements after addition: [Mango, Banana, Orange, Papaya, Mango]
Size of ArrayList:5
ArrayList elements after deletion: [Mango, Banana, Orange, Papaya]
ArrayList elements after deletion: [Mango, Orange, Papaya]
Size of ArrayList after deletion: 3
The element at 2nd index is: Papaya

LinkedList Class

The LinkedList class extends the AbstractSequentialList and implements the List and Deque interfaces.
The manipulations of the elements in LinkedList are fast as compared to ArrayList.

Example : A simple example of LinkedList in Java

import java.util.*;
public class LinkedListDemo
{
      public static void main(String args[])
      {
             // create a linked list
             LinkedList<String> ll = new LinkedList<String>();
             System.out.println("Initial size of LinkedList: "+ll.size());

             // add elements to the linked list
             ll.add("Java");
             ll.add("C++");
             ll.add("PHP");
             ll.add("DBMS");
             ll.add("CSS");
             ll.addLast("JavaScript");
             ll.addFirst("HTML");
             System.out.println("Element of LinkedList: " + ll);
             System.out.println("Size of LinkedList after addition: "+ll.size());

             // remove elements from the linked list
             ll.remove("PHP");
             ll.remove(4);
             System.out.println("Element of LinkedList after deletion: " + ll);
             System.out.println("Size of the LinkedList after deletion: "+ll.size());

             // remove first and last elements
             ll.removeFirst();
             ll.removeLast();
             System.out.println("ll after deleting first and last: " + ll);
             System.out.println("Size of the LinkedList after deletion: "+ll.size());

             //Retriving First and Last element
             System.out.println("Fisrt element of LinkedList: "+ll.getFirst());
             System.out.println("Last element of LinkedList: "+ll.getLast());

             Iterator<String> itr = ll.iterator();
             while(itr.hasNext())
             {
                   System.out.print(itr.next()+", ");
             }
      }
}

Output:
Initial size of LinkedList: 0
Element of LinkedList: [HTML, Java, C++, PHP, DBMS, CSS, JavaScript]
Size of the LinkedList after addition: 7
Element of LinkedList after deletion: [HTML, Java, C++, DBMS, JavaScript]
Size of the LinkedList after deletion: 5
ll after deleting first and last: [Java, C++, DBMS]
Size of LinkedList after deletion: 3
Fisrt element of LinkedList: Java
Last element of LinkedList: DBMS
Java, C++, DBMS

Difference between ArrayList and LinkedList

ArrayList	LinkedList
Serach operation in ArrayList is fast compared to LinkedList.	Searching in LinkedList is slow.
ArrayList cannot be iterated in reverse order.	LinkedList can be iterated in reverse direction by using descendingIterator().
Insertion and deletion is slow is compared to LinkedList.	Insertion and deletion are easy and fast in LinkedList.
ArrayList works as the list, because it implements List only.	LinkedList implements both List and Deque interface.
ArrayList maintains only index and element data.	LinkedList maintais the element data and two pointers for neighbor nodes.