Book Image

Practical Design Patterns for Java Developers

By : Miroslav Wengner
Book Image

Practical Design Patterns for Java Developers

By: Miroslav Wengner

Overview of this book

Design patterns are proven solutions to standard problems in software design and development, allowing you to create reusable, flexible, and maintainable code. This book enables you to upskill by understanding popular patterns to evolve into a proficient software developer. You’ll start by exploring the Java platform to understand and implement design patterns. Then, using various examples, you’ll create different types of vehicles or their parts to enable clarity in design pattern thinking, along with developing new vehicle instances using dedicated design patterns to make the process consistent. As you progress, you’ll find out how to extend vehicle functionalities and keep the code base structure and behavior clean and shiny. Concurrency plays an important role in application design, and you'll learn how to employ a such design patterns with the visualization of thread interaction. The concluding chapters will help you identify and understand anti-pattern utilization in the early stages of development to address refactoring smoothly. The book covers the use of Java 17+ features such as pattern matching, switch cases, and instances of enhancements to enable productivity. By the end of this book, you’ll have gained practical knowledge of design patterns in Java and be able to apply them to address common design problems.
Table of Contents (14 chapters)
1
Part 1: Design Patterns and Java Platform Functionalities
4
Part 2: Implementing Standard Design Patterns Using Java Programming
8
Part 3: Other Essential Patterns and Anti-Patterns

Initiating objects on demand with the lazy initialization pattern

This pattern’s purpose is to defer an instance of the desired class instance until the client actually requests it.

Motivation

Although operational memory has grown drastically over the years, we learned in the previous chapter that the JVM allocated a defined, specific size of memory reserved for the heap. When the heap is exhausted and the JVM is unable to allocate any new object, it causes an out of memory error. Lazy handling can have quite a positive impact on this heap pollution. It is sometimes also called asynchronous loading because of the delayed instance. The pattern has quite a nice use in a web application where the web page is generated on demand rather than during the application initialization process. It also has its place in an application, where the cost of operating the relevant object is high.

Finding it in the JDK

Lazy initialization can be demonstrated using the example of dynamic...