How to intersect two sets in Java using java.util.Set data structure.

Set Intersection

Set is a collection that holds non-duplicate data. Set itself is an interface and has several implementing classes. Here are some know implementation of Set.

  • AbstractSet
  • ConcurrentSkipListSet
  • CopyOnWriteArraySet
  • EnumSet
  • HashSet
  • JobStateReasons
  • LinkedHashSet
  • TreeSet

In the example below, I have used HashSet to create two different sets. One set contains the name of all the developers of a fictitious team. Another set contains names of all the tech leads for that team. We are intersted to know what all tech leads are also developers. This can be done by doing an intersection of two sets. Intersection of sets can be done by calling retainAll() method as show below.


import java.util.HashSet;
import java.util.Set;

 * @author Kushal Paudyal
 * Created on: 02/19/2014
 * Last Modified On: 02/19/2014
public class SetIntersection {
	public static void main(String args [] ) {
		 * Prepare a set of Developers
		Set<String> developers = new HashSet<String>();
		System.out.println("Developers: " + developers.toString());
		 * Prepare a set of Tech Leads
		 * Note that some of the items added are duplicates.
		 * Set does not allow duplicates which is apparent console print.
		Set<String> techLeads = new HashSet<String>();
		techLeads.add("Kushal"); //set does not allow duplicates
		System.out.println("Tech Leads: " + techLeads.toString());
		 * To do set intersection, you can call retainAll() method
		 * and pass another set as parameter.
		System.out.println("Tech Leads who are also developers:" + developers);


Here is the output of this program:

Developers: [Kushal, Pradip, Madan, Nick]
Tech Leads: [Kushal, Matthew, Nick]
Tech Leads who are also developers:[Kushal, Nick]
[My Video Promotion]
  1. Implementing a Simple LIFO Stack in Java using LinkedList
  2. Implementing a Simple FIFO Queue in Java Using Linked List
  3. In Place Matrix (2D Array) Clockwise and Counterclockwise Rotation – Java Implementation
  4. Matrix (2D Array) Clockwise and Counterclockwise Rotation with Extra Buffer – Java Implementation
  5. Array Max Integer Finder (With Big O Analysis)
  6. A Basic Implementation of Binary Tree in Java
  7. A Basic Implementation of Generic Tree in Java
  8. Basic example of implementing Singly Linked List in Java
  9. How to Add and Remove nodes in an unsorted Linked List
  10. Rotating a two dimensional integer array In-Place and using extra memory
  11. How to reverse a Singly Linked List iteratively and recursively
  12. Sorted Circular Linked List Implementation And Insert Operation
  13. Finding Mean Value Of An Integer Array In Java
  14. How to intersect two sets in Java using java.util.Set data structure.
  15. Bubble Sorting An Integer Array In Ascending and Descending Order
  16. How to split strings and separate the words with spaces
  17. How to easily sort characters in a String?
Tagged , , , . Bookmark the permalink.

One Response to How to easily sort characters in a String?

  1. Why visitors still use to read news papers when in this technological world all is available on net?

Leave a Reply

Your email address will not be published. Required fields are marked *

This site uses Akismet to reduce spam. Learn how your comment data is processed.