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