Java Set Interface

In this tutorial, we will learn about the Set interface in Java and its methods.

The Set interface of the Java Collections framework provides the features of the mathematical set in Java. It extends the Collection interface.

The set interface present in the java.util package and extends the Collection interface is an unordered collection of objects in which duplicate values cannot be stored. It is an interface which implements the mathematical set. This interface contains the methods inherited from the Collection interface and adds a feature which restricts the insertion of the duplicate elements. There are two interfaces which extend the set implementation namely SortedSet and NavigableSet.

Example:

// Java program to demonstrate a Set 

import java.util.*; 
public class SetExample{ 
	public static void main(String[] args) 
	{ 
		// Set demonstration using HashSet 
		Set<String >hash_Set 
			= new HashSet <String>(); 

		hash_Set.add("Codemistic"); 
		hash_Set.add("For"); 
		hash_Set.add("Codemistic"); 
		hash_Set.add("Example"); 
		hash_Set.add("Set"); 

		System.out.println(hash_Set); 
	} 
} 

output:
[Set, Example, Codemistic, For]

Set Operations

The Java Set interface allows us to perform basic mathematical set operations like union, intersection, and subset.
• Union - to get the union of two sets x and y, we can use x.addAll(y)
• Intersection - to get the intersection of two sets x and y, we can use x.retainAll(y)
• Subset - to check if x is a subset of y, we can use y.containsAll(x)

Methods in Java Set Interface