Book Image

Design Patterns and Best Practices in Java

By : Kamalmeet Singh, Adrian Ianculescu, Lucian-Paul Torje
Book Image

Design Patterns and Best Practices in Java

By: Kamalmeet Singh, Adrian Ianculescu, Lucian-Paul Torje

Overview of this book

Having a knowledge of design patterns enables you, as a developer, to improve your code base, promote code reuse, and make the architecture more robust. As languages evolve, new features take time to fully understand before they are adopted en masse. The mission of this book is to ease the adoption of the latest trends and provide good practices for programmers. We focus on showing you the practical aspects of smarter coding in Java. We'll start off by going over object-oriented (OOP) and functional programming (FP) paradigms, moving on to describe the most frequently used design patterns in their classical format and explain how Java’s functional programming features are changing them. You will learn to enhance implementations by mixing OOP and FP, and finally get to know about the reactive programming model, where FP and OOP are used in conjunction with a view to writing better code. Gradually, the book will show you the latest trends in architecture, moving from MVC to microservices and serverless architecture. We will finish off by highlighting the new Java features and best practices. By the end of the book, you will be able to efficiently address common problems faced while developing applications and be comfortable working on scalable and maintainable projects of any size.
Table of Contents (15 chapters)
Title Page
Packt Upsell
Contributors
Preface
Index

The iterator pattern


The iterator pattern is probably one of the most well-known patterns in Java. Some Java programmers are using it without being aware that the collection package is an implementation of the iterator pattern, regardless of the type of the collection: array, list, set, or any other types.

The fact that we can deal in the same way with a collection, regardless of whether it's a list or an array, is because it provides a mechanism to iterate through its elements without exposing its internal structure. What's more, the same unified mechanism is used by different types of collections. The mechanism is called the iterator pattern.

Intent

The iterator pattern provides a way to traverse the elements of an aggregate object sequentially without exposing its internal representation.

Implementation

The iterator pattern is based on two abstract classes or interfaces, which can be implemented by pairs of concrete classes. The class diagram is as follows:

The following classes are used in...