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Learn Kotlin Programming

You're reading from   Learn Kotlin Programming A comprehensive guide to OOP, functions, concurrency, and coroutines in Kotlin 1.3

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Product type Paperback
Published in May 2019
Publisher Packt
ISBN-13 9781789802351
Length 514 pages
Edition 2nd Edition
Languages
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Authors (2):
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Stefan Bocutiu Stefan Bocutiu
Author Profile Icon Stefan Bocutiu
Stefan Bocutiu
Stephen Samuel Stephen Samuel
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Stephen Samuel
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Toc

Table of Contents (21) Chapters Close

Preface 1. Section 1: Fundamental Concepts in Kotlin FREE CHAPTER
2. Getting Started with Kotlin 3. Kotlin Basics 4. Object-Oriented Programming in Kotlin 5. Section 2: Practical Concepts in Kotlin
6. Functions in Kotlin 7. Higher-Order Functions and Functional Programming 8. Properties 9. Null Safety, Reflection, and Annotations 10. Generics 11. Data Classes 12. Collections 13. Testing in Kotlin 14. Microservices with Kotlin 15. Section 3: Advanced Concepts in Kotlin
16. Concurrency 17. Coroutines 18. Application of Coroutines 19. Kotlin Serialization 20. Other Books You May Enjoy

The hashCode and equals methods generated for you

Every type is derived from Any, which comes with a hashCode method declaration. This is the equivalent of a Java object class's hashCode method. This method is important when you want to place your instances in a collection, such as a map.

An object's hash code allows algorithms and data structures to place the instances in buckets. Imagine you implement a phone book. You'll place any name that starts with A in the A section, any name that starts with B in the B section, and so on. This simple approach allows you to search for someone quickly. This is how hash-based collections, such as HashMap and HashSet, are implemented.

When implementing the method, you need to adhere to a contract:

  • When invoked on the same object more than once during runtime, the hashCode method must consistently return the same value, given...
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