Java – ArrayList and LinkedList

I have decided to treat ArrayList and LinkedList together. This is because they are basically the same from the programmer’s view. So you use almost the same syntax for both. We would see this in a minute.

Also note that ArrayList and LinkedList both inherites from the List class. So I would refer to both of them as just List.

A list stores a sequence of elements which could be of the same or of different data types.

You probably would want to know ‘difference between ArrayList and Array‘. The main difference is that ArrayList support different data types while Array support just one data type.

Read about Arrays in Java Here

Properties of Lists

Take note of the following properties of a List. It applies both to ArrayList and LinkedList.

• You can reference element in a list using the index position of the element in the list. Indexes start from 0.
• Duplicate elements are allowed in a list.
• List provide several methods used to manipulate the elements

ArrayList and LinkedList Methods

So we have methods that apply to both ArrayList and LinkedList. This are given below.

Lets’ take and example

I recommend you try this yourself. The codes creates both an ArrayList and a LinkedList.

import java.util.ArrayList;
import java.util.LinkedList;

// ** Arrays, ArrayList and Linked List ***************
public class ListDemo {

	public static void main(String[] args) {
		
		ArrayList alist = new ArrayList();		
		alist.add("Osondu");
		alist.add("Saffron");
		alist.add("Oleander");
		alist.add(23.87);
		alist.add('A');
		System.out.println("\nElement of ArrayList: ");
		System.out.println("\t" + alist);
		
		LinkedList llist = new LinkedList();		
		llist.add("Osondu");
		llist.add("Saffron");
		llist.add("Oleander");
		llist.add(23.87);
		llist.add('A');
		System.out.println("\nElement of LinkedList: ");
		System.out.println("\t" + llist);	
	}
}

Listing 1.0: Array List and LinkedList

If you execute the code in Listing 1.0, then you will have the output below:

Element of ArrayList: 
	[Osondu, Saffron, Oleander, 23.87, A]

Element of LinkedList: 
	[Osondu, Saffron, Oleander, 23.87, A]

You can therefore see that ArrayLists and LinkedList are very similar.