Java 23 for Absolute Beginners: Learn the Fundamentals of Java Programming

Write your first code in Java 23 using simple, step-by-step examples that model real-word objects and events, making learning easy. With this book you will be able to pick up core programming concepts without fuss and write efficient Java code in no time. Clear code descriptions and layout ensure you get your code running as soon as possible. Author Iuliana Cosmina focuses on practical knowledge and getting you up to speed quickly―all the bits and pieces a novice needs to get started programming in Java. In this edition, you will discover how Java has changed since version 17, and how to design and write code using the most recently introduced Java features such as new collection methods, virtual threads, pattern and record matching in switch expressions, structured concurrency tasks, unnamed classes and instance methods, and many more. This book is a complete Java guide, covering the following topics: setting up a development environment, programming concepts and well-known programming principles, writing Java code following industry-specific design patterns and coding conventions, executing it, debugging, testing, documenting it and even using specialized tools such as IntelliJ IDEA for writing Java code, Maven for building, JUnit Jupiter for testing, and in-memory and Docker-hosted databases or data storage. After reading this book, you’ll have all the necessary skills and knowledge to pass an interview for a starting Java development position. What You Will Learn Set up a Java development environment Use the Java language to write high-quality code Understand fundamental programming concepts and algorithms Use virtual threads, records, and other Java renown features Debug, test, and document Java code Improve performance by customizing the Garbage Collector Who This Book Is For Those who are new to programming and want to learn Java and use it to build efficient solutions Table of Contents About the Author About the Technical Reviewer Acknowledgments Chapter 1: An Introduction to Java and Its History How It All Started Who This Book Is For How This Book Is Structured Conventions When Java Was Owned by Sun Microsystems How Is Java Portable? Sun Microsystem’s Java Versions Oracle Takes Over Java 7 Java 8 Java 9 Java 10 Java 11 Java 12 Java 13 Java 14 Java 15 Java 16 Java 17 Java 18 Java 19 Java 20 Java 21 Java 22 Java 23 Prerequisites Summary Chapter 2: Preparing Your Development Environment Installing Java The JAVA_HOME Environment Variable JAVA_HOME on Windows JAVA_HOME on macOS JAVA_HOME on Linux Running Java Code Using JShell Running Java Source Files Directly Using Java 21 Running Java Source Files Directly Using Java 22 Installing Apache Maven Installing Git Install a Java IDE Summary Chapter 3: Getting Your Feet Wet Core Syntax Parts Java Fundamental Building Blocks: Packages, Modules, and Classes Packages Access Modifiers Modules Advanced Module Configurations How to Determine the Structure of a Java Project The HelloWorld! Project in IntelliJ IDEA The HelloWorld! Project Compiled and Executed from the Command Line Putting the HelloWorld Class in a Package Configuring the com.sandbox Module Java Projects Using Build Tools, Mostly Maven Explaining and Enriching the Hello World! Class Summary Chapter 4: Java Syntax Base Rules of Writing Java Code Package Declaration Import Section Java Grammar Java Identifiers and Variables Java Comments Java Types Classes Fields Class Variables Encapsulating Data Methods Constructors Abstraction and Inheritance Enums Interfaces Default Methods in Interfaces Static Methods and Constants in Interfaces Private Methods in Interfaces Records Sealed Classes and Interfaces Hidden Classes Annotation Types Lambda Expressions Exceptions Catch the exception, print an appropriate message, and exit the application Throw an appropriate exception type Perform a dummy initialization try/catch Blocks Generics var and the Diamond Operator Unnamed Patterns and Unnamed Variables Summary Java Keywords Chapter 5: Data Types Stack and Heap Memory Introduction to Java Data Types Primitive Data Types Reference Data Types Java Primitive Types The boolean Type The char Type Numeric Primitive Types Java Integer Primitive Types Java Real Primitive Types Java Reference Types Arrays The String Type Useful String Methods Added After Java 8 Escaping Characters Text Blocks String Concatenation Wrapper Classes for Primitive Types Date/Time API Collections Concurrency-Specific Types Classic Thread Creation (Before Java 21) Java 21 Threads New Syntax and Virtual Threads Asynchronous Programming Using CompletableFuture Structured Concurrency Summary Chapter 6: Operators The Assignment Operator Explicit Type Conversion: (typem) and instanceof Type Patterns Record Patterns Primitive Patterns Numerical Operators Unary Operators Incrementors and Decrementors Sign Operators Negation Operator Binary Operators The + (Plus/Addition/Concatenation) Operator The - (Minus) Operator The * (Multiply) Operator The / (Divide) Operator The % (Modulus) Operator Relational Operators The == (Equals) Operator The Other Comparison Operators Bitwise Operators Bitwise (~) NOT Bitwise (&) AND Bitwise Inclusive (|) OR Bitwise Exclusive (^) OR Logical Operators Shift Operators The < > Shift Right Operator The >>> Unsigned Shift Right Operator The Elvis Operator Summary Chapter 7: Controlling the Flow if-else Statement switch The Classic switch Statement The switch Expression switch with String Options switch with enum Options Pattern Matching for switch Record Patterns for switch Looping Statements for Statement while Statement do-while Statement Breaking Loops and Skipping Steps break Statement continue Statement return Statement Controlling the Flow Using try-catch Constructions Summary Chapter 8: The Stream API Introduction to Streams Creating Streams Creating Streams from Collections Creating Streams from Arrays Creating Empty Streams Creating Finite Streams Streams of Primitives and Streams of Strings Short Introduction to Optional How to Use Streams Like a Pro Terminal Functions forEach and forEachOrdered Intermediate Operation filter and Terminal Operation toArray Intermediate Operations map and flatMap and Terminal Operation collect Intermediate Operation sorted and Terminal Operation findFirst Intermediate Operation distinct and Terminal Operation count Intermediate Operation limit and Terminal Operations min and max Terminal Operations sum and reduce Intermediate Operation peek Intermediate Operation skip and Terminal Operations findAny, anyMatch, allMatch, and noneMatch Intermediate Operation gather Creating a Custom Gatherer Built-In Gatherers Debugging Stream Pipelines Summary Chapter 9: Debugging, Testing, and Documenting Debugging Logging Logging with System.out.print Logging with JUL Logging with SLF4J and Logback Debug Using Assertions Step-By-Step Debugging Inspect a Running Application Using Java Tools jps jcmd jconsole Using JDK Mission Control Accessing the Java Process API Testing Test Code Location Building an Application to Test Introducing JUnit Using Fakes Using Stubs Using Mocks Documenting Summary Chapter 10: Making Your Application Interactive Reading User Data from the Command Line Using System.in Using java.util.Scanner Using java.io.Console Building Applications Using Swing Introducing JavaFX Internationalization Building a Web Application Simple Application Server The jwebserver Command-Line Tool Using SimpleFileServer Java Web Application with an Embedded Server Java Web Application on a Standalone Server Summary Chapter 11: Working with Files Java IO and NIO APIs File Handlers isFile getAbsolutePath getParent, getName, length, isHidden, canRead, and canWrite Handling Directories: list() and listFiles() createNewFile(), exists(), createTempFile(..), and deleteOnExit() renameTo Path Handlers Reading Files Using Scanner to Read Files Using Files Utility Methods to Read Files Using Readers to Read Files Using InputStream to Read Files Writing Files Writing Files Using Files Utility Methods Using Writer to Write Files Using OutputStream to Write Files Using Java NIO to Manage Files Serialization and Deserialization Byte Serialization XML Serialization JSON Serialization The Media API Using JavaFX Image Classes Writing and Reading from Databases Summary Chapter 12: The Publish/Subscribe Framework Reactive Programming and the Reactive Manifesto Using the JDK Reactive Streams API Reactive Streams Technology Compatibility Kit Using Project Reactor Summary Chapter 13: Garbage Collection Garbage Collection Basics Oracle HotSpot JVM Architecture How Many Garbage Collectors Are There? Working with Garbage Collection from the Code Using the finalize() Method Heap Memory Statistics Using Cleaner Preventing GC from Deleting an Object Using Weak References Garbage Collection Exceptions and Causes Summary Appendix A: Java Modules Modules Advanced Module Configurations Appendix B: IntelliJ IDEA Modules Index