Java 8 to 21: Explore and work with the cuttingedge features of Java 21

Title Page....2

Copyright Page....3

Dedication....4

About the Authors....5

About the Reviewers....6

Table of Contents....13

1. Hello Java....21

Introduction....21

Structure....21

Objectives....22

Requirements....22

Setting up a project....23

Hello Java....25

Principals of OOP....28

Encapsulation....29

Inheritance....36

Polymorphism....39

Built-in types....41

Arrays....43

Generics and Erasure....44

Debugging....48

Debugging Java....49

Conclusion....50

Points to remember....50

Multiple choice questions....51

Answers....52

2. OOP Patterns....54

Introduction....54

Structure....54

Objectives....55

Why OOP?....55

Basic Object-Oriented Design....56

Common patterns....57

Singleton....58

Factory....64

Builder....66

Adapter....70

Façade....72

Proxy....73

Observer....77

Command....79

Iterator....81

Immutability....83

Functional programming....85

Conclusion....87

Points to remember....88

Multiple choice questions....88

Answers....89

3. 8 to 21 to GraalVM....91

Introduction....91

Structure....92

Objectives....93

Java 8—the baseline....93

Lambda expressions....94

Method references....95

Default methods....96

Streams....97

Annotation changes....97

Method parameters reflection....98

New date and time APIs....98

VM changes....99

Modules AKA Jigsaw (Java 9)....100

Shenandoah (Java 12)....101

Not your fathers stop the world mark sweep....102

Generational garbage collection....102

Concurrent versus parallel garbage collector....102

Serial collector....103

Parallel collector or throughput collector....103

G1 Garbage Collector....104

Z Garbage Collector (ZGC)....104

Shenandoah....105

Microbenchmark Suite (Java 12)....105

Virtual Threads—Loom (Java 21)....108

Loom....110

Deprecation of finalization (Java 9)....113

UTF-8 by default (Java 18)....114

Language changes....115

Try with resources....115

Private methods in interfaces (Java 9)....116

var keyword (Java 10)....116

Switch expression (Java 14)....116

Sealed classes (Java 17)....119

Pattern-matching instanceof (Java 16)....120

Text blocks (Java 15)....120

Records (Java 16)....122

Record patterns (Java 19 preview)....122

String templates (Java 21 preview)....122

Unnamed patterns and variables (Java 21 preview)....123

APIs....124

HttpClient (Java 11)....124

Foreign function and memory API—Panama (Java 19)....125

Structured concurrency (Java 19)....126

Serialization filtering (Java 9)....127

Scoped values (Java 20)....128

Sequenced collection (Java 21)....129

Future....130

GraalVM....130

Valhalla....131

Conclusion....133

Points to remember....133

Multiple choice questions....133

Answers....134

4. Modern Threading....136

Introduction....136

Structure....136

Objectives....137

History....137

Concepts....139

Thread safety....140

Mutex (Lock)....141

Wait and notify (monitor)....143

Deadlock....146

Race conditions....147

Thread pools....148

Executors....148

Locks....150

Synchronizers....161

Atomic....164

Futures....165

Collections and queues....166

Conclusion....168

Points to remember....169

Multiple choice questions....169

Answers....170

5. It’s Springtime in Java....172

Introduction....172

Structure....172

Objectives....173

History and origin....173

Inversion of Control, Dependency Injection, and Aspect Oriented Programming....174

Hello Spring Boot....178

A REST API....184

Spring MVC and Thymeleaf....188

SQL and JDBC....200

SQL basics....200

Java Database Connectivity....202

Java Persistence Architecture....206

Error handling....212

Conclusion....215

Points to remember....215

Multiple choice questions....216

Answers....217

6. Testing and CI....219

Introduction....219

Structure....219

Objectives....220

Testing theory....220

JUnit....222

Mockito....225

Performance matters....227

What should we mock?....228

Test Driven Development....228

The problem with TDD....229

Continuous Integration....230

Continuous Integration tools....231

Cloud versus on premise....232

Agent statefullness....233

GitHub Actions....234

Branch protection....240

Linting....242

Conclusion....249

Points to remember....249

Multiple choice questions....250

Answers....251

7. Docker, Kubernetes, and Spring Native....253

Introduction....253

Structure....253

Objectives....254

Containers....254

Docker....255

Orchestration....258

Kubernetes (k8s)....259

The easy way—Skaffold....264

Infrastructure as Code (IaC)....271

Spring Native....273

Getting started with Spring Native....275

Cloud Native....278

Alternatives to Spring Native....279

Conclusion....281

Points to remember....281

Multiple choice questions....282

Answers....283

8. Microservices....285

Introduction....285

Structure....285

Objectives....286

Microservices versus small Monoliths....286

Service mesh....289

Authentication and authorization....292

Eventual consistency....298

Messaging....304

RabbitMQ....306

Apache Kafka....306

Spring cloud stream....307

Publish subscribe and point to point....308

Monolith first....313

Modular Monolith....315

Modulith....316

Other modules....318

The benefit....318

Conclusion....319

Points to remember....319

Multiple choice questions....319

Answers....320

9. Serverless....322

Introduction....322

Structure....322

Objectives....323

What is serverless....323

Using AWS Lambda....324

GraalVM and Monolith serverless....332

The cloud ecosystem....336

Conclusion....337

Points to remember....338

Multiple choice questions....338

Answers....339

10. Monitoring and Observability....341

Introduction....341

Structure....342

Objectives....342

What is monitoring?....342

Pillars of observability....344

The three pillars of observability....345

What makes a system observable?....346

Prometheus....348

Grafana....350

Micrometer....351

Actuator....353

Enabling and configuring Spring Boot actuator....354

Exposing custom information via Spring Boot actuator....355

Developer observability....357

Injecting logs....358

Snapshots/captures and non-breaking breakpoints....360

PII reduction and blocklists....361

Conclusion....362

Points to remember....362

Multiple choice questions....363

Answers....363

Index....365

Are you still using Java in the same old way? Java 21 has evolved into a dynamic and concise language with a vibrant and rich ecosystem. If you're seeking to expand your knowledge of modern Java programming, this book is the ideal resource for you.

This practical book offers valuable guidance on effectively utilizing the latest syntax enhancements in order to write code that is both streamlined and easy to understand. It not only provides detailed insights into the inner workings of the Java virtual machine (JVM), but also equips you with the knowledge necessary to excel in building scalable and resilient applications using a variety of powerful techniques such as Spring Boot, Spring Native, GraalVM, and other innovative methodologies. Furthermore, the book assists you in navigating the complexities of testing and packaging, helping you comprehend and navigate intricate processes. It also introduces you to cutting-edge deployment methodologies that leverage Docker and Kubernetes, ensuring that you stay up to date with the most recent advancements in software development and deployment practices.

By the time you finish reading this book, you will have upgraded your Java programming techniques and gained the ability to fully exploit the latest and greatest advancements in the language.

What you will learn

• Explore different techniques for developing multithreaded applications in Java.
• Harness the power of modern Java and Spring Boot 3+ to elevate your server development capabilities.
• Utilize the power of Docker, Kubernetes, and Spring Native to streamline your cloud-based deployments.
• Integrate unit testing, Mockito, and continuous integration (CI) into your Java projects.
• Use Prometheus and Grafana to monitor the performance of your Java applications.

Who this book is for

This book is suitable for individuals who are new to Java and have little to no experience but possess a basic understanding of the syntax. Additionally, it provides valuable insights for developers who may have not utilized Java in a significant timeframe.