Book Image

The Java Workshop

By : David Cuartielles, Andreas Göransson, Eric Foster-Johnson
4 (2)
Book Image

The Java Workshop

4 (2)
By: David Cuartielles, Andreas Göransson, Eric Foster-Johnson

Overview of this book

Java is a versatile, popular programming language used across a wide range of industries. Learning how to write effective Java code can take your career to the next level, and The Java Workshop will help you do just that. This book is designed to take the pain out of Java coding and teach you everything you need to know to be productive in building real-world software. The Workshop starts by showing you how to use classes, methods, and the built-in Collections API to manipulate data structures effortlessly. You’ll dive right into learning about object-oriented programming by creating classes and interfaces and making use of inheritance and polymorphism. After learning how to handle exceptions, you’ll study the modules, packages, and libraries that help you organize your code. As you progress, you’ll discover how to connect to external databases and web servers, work with regular expressions, and write unit tests to validate your code. You’ll also be introduced to functional programming and see how to implement it using lambda functions. By the end of this Workshop, you’ll be well-versed with key Java concepts and have the knowledge and confidence to tackle your own ambitious projects with Java.
Table of Contents (20 chapters)

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...