Difference Between List and Set in Java

The List interface allows storing the ordered collection. It is a child interface of Collection. It is an ordered collection of objects in which duplicate values are allowed to store. List preserves the insertion order, it allows positional access and insertion of elements.

Declaration:

public abstract interface List extends Collection

The set interface in the java.util package and extends Collection interface is an unordered collection of objects in which duplicate values cannot be stored. It is an interface that implements the maths set. This interface contains the methods inherited from the Collection interface and adds a feature that restricts to insert the duplicate elements. 

Declaration: The Set interface is declared as:

public interface Set extends Collection

Example:

Input :  Add Elements = [1, 2, 3, 1]
Output:  Set = [1, 2, 3]
     List = [1, 2, 3, 1]

Input :  Add Elements = [a, b, d, b]
Output:  Set = [a, b, d]
     List = [a, b, d, b]

Below is the illustration of Set and List :

// Implementation of List and Set in Java
import java.io.*;
import java.util.*;

class GFG {
    public static void main(String[] args)
    {
        // List declaration
        List<Integer> l = new ArrayList<>();
        l.add(5);
        l.add(6);
        l.add(3);
        l.add(5);
        l.add(4);

        // Set declaration
        Set<Integer> s = new HashSet<>();
        s.add(5);
        s.add(6);
        s.add(3);
        s.add(5);
        s.add(4);

        // printing list
        System.out.println("List = " + l);
        // printing Set
        System.out.println("Set = " + s);
    }
}

List = [5, 6, 3, 5, 4]
Set = [3, 4, 5, 6]

Difference between List and Set: