Search icon CANCEL
Arrow left icon
Explore Products
Best Sellers
New Releases
Books
Videos
Audiobooks
Learning Hub
Conferences
Free Learning
Arrow right icon
Arrow up icon
GO TO TOP
Java Fundamentals

You're reading from   Java Fundamentals A fast-paced and pragmatic introduction to one of the world's most popular programming languages

Arrow left icon
Product type Paperback
Published in Mar 2019
Publisher
ISBN-13 9781789801736
Length 408 pages
Edition 1st Edition
Languages
Arrow right icon
Authors (5):
Arrow left icon
Miles Obare Miles Obare
Author Profile Icon Miles Obare
Miles Obare
Basheer Ahamed Fazal Basheer Ahamed Fazal
Author Profile Icon Basheer Ahamed Fazal
Basheer Ahamed Fazal
Rogério Theodoro de Brito Rogério Theodoro de Brito
Author Profile Icon Rogério Theodoro de Brito
Rogério Theodoro de Brito
Gazihan Alankus Gazihan Alankus
Author Profile Icon Gazihan Alankus
Gazihan Alankus
Vinicius Isola Vinicius Isola
Author Profile Icon Vinicius Isola
Vinicius Isola
+1 more Show less
Arrow right icon
View More author details
Toc

Table of Contents (12) Chapters Close

Java Fundamentals
Preface
1. Introduction to Java 2. Variables, Data Types, and Operators FREE CHAPTER 3. Control Flow 4. Object-Oriented Programming 5. OOP in Depth 6. Data Structures, Arrays, and Strings 7. The Java Collections Framework and Generics 8. Advanced Data Structures in Java 9. Exception Handling Appendix

Set and Uniqueness in Set


In this topic, we are going to learn the logic behind a set that finds the uniqueness of an object being added and understand the importance of two object-level methods.

The magic lies in two methods of the Object class

  • hashCode()

  • equals()

Basic Rules for the equals() and hashCode() Methods

  • Two objects can be identical only when the value returned using the hashcode() method is identical and the equal() method returns true.

  • If the two objects return the same hashCode() value, it doesn't necessarily mean both objects are the same (as hash values may collide with other objects as well). In that case, it's necessary to find the equality by calling equals() and verifying the identity.

  • We can't use hashCode() alone to find out the equality; we need to use equals() as well to do this. However, hashCode() alone is enough to find the inequality. If the hashCode() returns different values, it's safe to consider the objects different.

Adding an Object to a Set

Though many things...

lock icon The rest of the chapter is locked
Register for a free Packt account to unlock a world of extra content!
A free Packt account unlocks extra newsletters, articles, discounted offers, and much more. Start advancing your knowledge today.
Unlock this book and the full library FREE for 7 days
Get unlimited access to 7000+ expert-authored eBooks and videos courses covering every tech area you can think of
Renews at €18.99/month. Cancel anytime