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Learn Java with Projects

You're reading from   Learn Java with Projects A concise practical guide to learning everything a Java professional really needs to know

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Product type Paperback
Published in Nov 2023
Publisher Packt
ISBN-13 9781837637188
Length 598 pages
Edition 1st Edition
Languages
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Authors (2):
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Maaike van Putten Maaike van Putten
Author Profile Icon Maaike van Putten
Maaike van Putten
Dr. Seán Kennedy Dr. Seán Kennedy
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Dr. Seán Kennedy
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Toc

Table of Contents (22) Chapters Close

Preface 1. Part 1: Java Fundamentals
2. Chapter 1: Getting Started with Java FREE CHAPTER 3. Chapter 2: Variables and Primitive Data Types 4. Chapter 3: Operators and Casting 5. Chapter 4: Conditional Statements 6. Chapter 5: Understanding Iteration 7. Chapter 6: Working with Arrays 8. Chapter 7: Methods 9. Part 2: Object-Oriented Programming
10. Chapter 8: Classes, Objects, and Enums 11. Chapter 9: Inheritance and Polymorphism 12. Chapter 10: Interfaces and Abstract Classes 13. Chapter 11: Dealing with Exceptions 14. Chapter 12: Java Core API 15. Part 3: Advanced Topics
16. Chapter 13: Generics and Collections 17. Chapter 14: Lambda Expressions 18. Chapter 15: Streams – Fundamentals 19. Chapter 16: Streams: Advanced Concepts 20. Chapter 17: Concurrency 21. Index

Explaining Optionals

An Optional can be thought of as a container that may or may not be empty. As per the API, the container “may or may not contain a non-null value”. An Optional is primarily used as a method return type where there is a real need to represent “no result” and when returning null could cause errors. Before Java 8, programmers would return null but now, since Java 8, we can return an empty Optional instead. This has several advantages:

  • Reduces the risk of NullPointerExceptions
  • By using Optional as the return type, the API can now clearly state that there may not be a value returned
  • The Optional API facilitates the functional programming style

As well as Optional<T>, there are Optionals for the primitive types also; namely: OptionalInt, OptionalDouble and OptionalLong. We will examine them later.

Let us first look at how to create Optionals.

Creating Optionals

The API provides several static methods for...

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