Difference between List and Set in Java

List and Set both interface belongs to the Collection framework. Both interfaces extend the Collection interface. They both are used to store a collection of objects as a single unit.

Before jdk1.2, we used to use Arrays, Vectors, and Hashtable for grouping objects as a single unit.

Sr. No.	Key	List	Set
1	Positional access	The list provides positional access of the elements in the collection.	Set doesn't provide positional access to the elements in the collection
2	Implementation	Implementation of List are ArrayList,LinkedList,Vector ,Stack	Implementation of a set interface is HashSet and LinkedHashSet
3	Duplicate	We can store the duplicate elements in the list.	We can’t store duplicate elements in Set
4	Ordering	List maintains insertion order of elements in the collection	Set doesn’t maintain any order
5	Null Element	The list can store multiple null elements	Set can store only one null element

Example of List

import java.util.List;
import java.util.ArrayList;
import java.util.LinkedList;
public class ListExample {
   public static void main(String[] args) {
      List<String> al = new ArrayList<String>();
      al.add("BMW");
      al.add("Audi");
      al.add("BMW");
      System.out.println("List Elements: ");
      System.out.print(al);
   }
}

Output

List Elements:
[BMW, Audi, BMW]

Example of Set

import java.util.Set;
import java.util.HashSet;
import java.util.TreeSet;
public class SetExample {
   public static void main(String args[]) {
      int count[] = {2, 4, 3, 5};
      Set<Integer> hset = new HashSet<Integer>();
      try{
         for(int i = 0; i<4; i++){
            hset.add(count[i]);
         }
         System.out.println(hset);
      }
      catch(Exception e){
         e.printStackTrace();
      }
   }
}

Output

[2, 4, 3, 5]