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The Java Workshop

You're reading from   The Java Workshop Learn object-oriented programming and kickstart your career in software development

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Product type Paperback
Published in Oct 2019
Publisher Packt
ISBN-13 9781838986698
Length 606 pages
Edition 1st Edition
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Authors (3):
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Eric Foster-Johnson Eric Foster-Johnson
Author Profile Icon Eric Foster-Johnson
Eric Foster-Johnson
Andreas Göransson Andreas Göransson
Author Profile Icon Andreas Göransson
Andreas Göransson
David Cuartielles David Cuartielles
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David Cuartielles
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Toc

Table of Contents (20) Chapters Close

Preface 1. Getting Started 2. Learning the Basics FREE CHAPTER 3. Object-Oriented Programming 4. Collections, Lists and Java's Built-In APIs 5. Exceptions 6. Libraries, Packages, and Modules 7. Databases and JDBC 8. Sockets, Files, and Streams 9. Working with HTTP 10. Encryption 11. Processes 12. Regular Expressions 13. Functional Programming with Lambda Expressions 14. Recursion 15. Processing Data with Streams 16. Predicates and Other Functional Interfaces 17. Reactive Programming with Java Flow 18. Unit Testing Appendix

Using Collectors

Collectors in Java are a very powerful tool when you need to extract certain data points, descriptions, or elements from large data structures. They offer a very understandable way of describing what you want to do with a stream of elements, without needing to write complex logic.

There are a number of helpful default implementations of the Collector interface that you can start using easily. Most of these collectors will not allow null values; that is, if they find a null value in your stream, they will throw a NullPointerException. Before using a collector to reduce your elements in any of these containers, you should take care to handle null elements in the stream.

The following is an introduction to all default Collectors:

  • toCollection: This generic collector will allow you to wrap your elements in any known class implementing the Collection interface; examples include ArrayList, HashSet, LinkedList, TreeSet, and others:
    List.of("one", &quot...
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