Core Java for the Impatient

Clear, Concise Guide to the Core Language and Libraries--Updated through Java 17 Modern Java introduces major enhancements that impact the core Java technologies and APIs at the heart of the Java platform. Many old Java idioms are no longer needed, and new features and programming paradigms can make you far more effective. However, navigating these changes can be challenging. Core Java for the Impatient, Third Edition, is a complete yet concise guide that reflects all changes through Java SE 17, Oracle's latest Long-Term Support (LTS) release. Written by Cay S. Horstmann--author of the classic two-volume Core Java --this indispensable tutorial offers a faster, easier pathway for learning modern Java. Horstmann covers everything working developers need to know, including the powerful concepts of lambda expressions and streams, modern constructs such as records and sealed classes, and sophisticated concurrent programming techniques. Given the size and scope of Java 17, there's plenty to cover, but it's presented in small chunks organized for quick access and easy understanding, with plenty of practical insights and sample code to help you quickly apply all that's new. Test code as you create it with JShell Improve your object-oriented design with records and sealed classes Effectively use text blocks, switch expressions, and pattern matching Understand functional programming with lambda expressions Streamline and optimize data management with the Streams API Use modern library features and threadsafe data structures to implement concurrency reliably Work with the modularized Java API and third-party modules Take advantage of API improvements for working with collections, input/output, regular expressions, and processes Learn the APIs for date/time processing and internationalization Whether you're an experienced developer just getting started with modern Java, or have been programming with Java for years, this guide will help you write more robust, efficient, and secure Java code. Register your book for convenient access to downloads, updates, and/or corrections as they become available. See inside book for details. Preface Acknowledgments About the Author 1 FUNDAMENTAL PROGRAMMING STRUCTURES 1.1 Our First Program 1.1.1 Dissecting the “Hello, World” Program 1.1.2 Compiling and Running a Java Program 1.1.3 Method Calls 1.1.4 JShell 1.2 Primitive Types 1.2.1 Signed Integer Types 1.2.2 Floating-Point Types 1.2.3 The char Type 1.2.4 The boolean Type 1.3 Variables 1.3.1 Variable Declarations 1.3.2 Identifiers 1.3.3 Initialization 1.3.4 Constants 1.4 Arithmetic Operations 1.4.1 Assignment 1.4.2 Basic Arithmetic 1.4.3 Mathematical Methods 1.4.4 Number Type Conversions 1.4.5 Relational and Logical Operators 1.4.6 Big Numbers 1.5 Strings 1.5.1 Concatenation 1.5.2 Substrings 1.5.3 String Comparison 1.5.4 Converting Between Numbers and Strings 1.5.5 The String API 1.5.6 Code Points and Code Units 1.5.7 Text Blocks 1.6 Input and Output 1.6.1 Reading Input 1.6.2 Formatted Output 1.7 Control Flow 1.7.1 Branches 1.7.2 Switches 1.7.3 Loops 1.7.4 Breaking and Continuing 1.7.5 Local Variable Scope 1.8 Arrays and Array Lists 1.8.1 Working with Arrays 1.8.2 Array Construction 1.8.3 Array Lists 1.8.4 Wrapper Classes for Primitive Types 1.8.5 The Enhanced for Loop 1.8.6 Copying Arrays and Array Lists 1.8.7 Array Algorithms 1.8.8 Command-Line Arguments 1.8.9 Multidimensional Arrays 1.9 Functional Decomposition 1.9.1 Declaring and Calling Static Methods 1.9.2 Array Parameters and Return Values 1.9.3 Variable Arguments Exercises 2 OBJECT-ORIENTED PROGRAMMING 2.1 Working with Objects 2.1.1 Accessor and Mutator Methods 2.1.2 Object References 2.2 Implementing Classes 2.2.1 Instance Variables 2.2.2 Method Headers 2.2.3 Method Bodies 2.2.4 Instance Method Invocations 2.2.5 The this Reference 2.2.6 Call by Value 2.3 Object Construction 2.3.1 Implementing Constructors 2.3.2 Overloading 2.3.3 Calling One Constructor from Another 2.3.4 Default Initialization 2.3.5 Instance Variable Initialization 2.3.6 Final Instance Variables 2.3.7 The Constructor with No Arguments 2.4 Records 2.4.1 The Record Concept 2.4.2 Constructors: Canonical, Custom, and Compact 2.5 Static Variables and Methods 2.5.1 Static Variables 2.5.2 Static Constants 2.5.3 Static Initialization Blocks 2.5.4 Static Methods 2.5.5 Factory Methods 2.6 Packages 2.6.1 Package Declarations 2.6.2 The jar Command 2.6.3 The Class Path 2.6.4 Package Access 2.6.5 Importing Classes 2.6.6 Static Imports 2.7 Nested Classes 2.7.1 Static Nested Classes 2.7.2 Inner Classes 2.7.3 Special Syntax Rules for Inner Classes 2.8 Documentation Comments 2.8.1 Comment Insertion 2.8.2 Class Comments 2.8.3 Method Comments 2.8.4 Variable Comments 2.8.5 General Comments 2.8.6 Links 2.8.7 Package, Module, and Overview Comments 2.8.8 Comment Extraction Exercises 3 INTERFACES AND LAMBDA EXPRESSIONS 3.1 Interfaces 3.1.1 Using Interfaces 3.1.2 Declaring an Interface 3.1.3 Implementing an Interface 3.1.4 Converting to an Interface Type 3.1.5 Casts and the instanceof Operator 3.1.6 The “Pattern-Matching” Form of instanceof 3.1.7 Extending Interfaces 3.1.8 Implementing Multiple Interfaces 3.1.9 Constants 3.2 Static, Default, and Private Methods 3.2.1 Static Methods 3.2.2 Default Methods 3.2.3 Resolving Default Method Conflicts 3.2.4 Private Methods 3.3 Examples of Interfaces 3.3.1 The Comparable Interface 3.3.2 The Comparator Interface 3.3.3 The Runnable Interface 3.3.4 User Interface Callbacks 3.4 Lambda Expressions 3.4.1 The Syntax of Lambda Expressions 3.4.2 Functional Interfaces 3.5 Method and Constructor References 3.5.1 Method References 3.5.2 Constructor References 3.6 Processing Lambda Expressions 3.6.1 Implementing Deferred Execution 3.6.2 Choosing a Functional Interface 3.6.3 Implementing Your Own Functional Interfaces 3.7 Lambda Expressions and Variable Scope 3.7.1 Scope of a Lambda Expression 3.7.2 Accessing Variables from the Enclosing Scope 3.8 Higher-Order Functions 3.8.1 Methods that Return Functions 3.8.2 Methods That Modify Functions 3.8.3 Comparator Methods 3.9 Local and Anonymous Classes 3.9.1 Local Classes 3.9.2 Anonymous Classes Exercises 4 INHERITANCE AND REFLECTION 4.1 Extending a Class 4.1.1 Super- and Subclasses 4.1.2 Defining and Inheriting Subclass Methods 4.1.3 Method Overriding 4.1.4 Subclass Construction 4.1.5 Superclass Assignments 4.1.6 Casts 4.1.7 Anonymous Subclasses 4.1.8 Method Expressions with super 4.2 Inheritance Hierarchies 4.2.1 Final Methods and Classes 4.2.2 Abstract Methods and Classes 4.2.3 Protected Access 4.2.4 Sealed Types 4.2.5 Inheritance and Default Methods 4.3 Object: The Cosmic Superclass 4.3.1 The toString Method 4.3.2 The equals Method 4.3.3 The hashCode Method 4.3.4 Cloning Objects 4.4 Enumerations 4.4.1 Methods of Enumerations 4.4.2 Constructors, Methods, and Fields 4.4.3 Bodies of Instances 4.4.4 Static Members 4.4.5 Switching on an Enumeration 4.5 Runtime Type Information and Resources 4.5.1 The Class Class 4.5.2 Loading Resources 4.5.3 Class Loaders 4.5.4 The Context Class Loader 4.5.5 Service Loaders 4.6 Reflection 4.6.1 Enumerating Class Members 4.6.2 Inspecting Objects 4.6.3 Invoking Methods 4.6.4 Constructing Objects 4.6.5 JavaBeans 4.6.6 Working with Arrays 4.6.7 Proxies Exercises 5 EXCEPTIONS, ASSERTIONS, AND LOGGING 5.1 Exception Handling 5.1.1 Throwing Exceptions 5.1.2 The Exception Hierarchy 5.1.3 Declaring Checked Exceptions 5.1.4 Catching Exceptions 5.1.5 The Try-with-Resources Statement 5.1.6 The finally Clause 5.1.7 Rethrowing and Chaining Exceptions 5.1.8 Uncaught Exceptions and the Stack Trace 5.1.9 API Methods for Throwing Exceptions 5.2 Assertions 5.2.1 Using Assertions 5.2.2 Enabling and Disabling Assertions 5.3 Logging 5.3.1 Should You Use the Java Logging Framework? 5.3.2 Logging 101 5.3.3 The Platform Logging API 5.3.4 Logging Configuration 5.3.5 Log Handlers 5.3.6 Filters and Formatters Exercises 6 GENERIC PROGRAMMING 6.1 Generic Classes 6.2 Generic Methods 6.3 Type Bounds 6.4 Type Variance and Wildcards 6.4.1 Subtype Wildcards 6.4.2 Supertype Wildcards 6.4.3 Wildcards with Type Variables 6.4.4 Unbounded Wildcards 6.4.5 Wildcard Capture 6.5 Generics in the Java Virtual Machine 6.5.1 Type Erasure 6.5.2 Cast Insertion 6.5.3 Bridge Methods 6.6 Restrictions on Generics 6.6.1 No Primitive Type Arguments 6.6.2 At Runtime, All Types Are Raw 6.6.3 You Cannot Instantiate Type Variables 6.6.4 You Cannot Construct Arrays of Parameterized Types 6.6.5 Class Type Variables Are Not Valid in Static Contexts 6.6.6 Methods May Not Clash after Erasure 6.6.7 Exceptions and Generics 6.7 Reflection and Generics 6.7.1 The Class Class 6.7.2 Generic Type Information in the Virtual Machine Exercises 7 COLLECTIONS 7.1 An Overview of the Collections Framework 7.2 Iterators 7.3 Sets 7.4 Maps 7.5 Other Collections 7.5.1 Properties 7.5.2 Bit Sets 7.5.3 Enumeration Sets and Maps 7.5.4 Stacks, Queues, Deques, and Priority Queues 7.5.5 Weak Hash Maps 7.6 Views 7.6.1 Small Collections 7.6.2 Ranges 7.6.3 Unmodifiable Views Exercises 8 STREAMS 8.1 From Iterating to Stream Operations 8.2 Stream Creation 8.3 The filter, map, and flatMap Methods 8.4 Extracting Substreams and Combining Streams 8.5 Other Stream Transformations 8.6 Simple Reductions 8.7 The Optional Type 8.7.1 Producing an Alternative 8.7.2 Consuming the Value If Present 8.7.3 Pipelining Optional Values 8.7.4 How Not to Work with Optional Values 8.7.5 Creating Optional Values 8.7.6 Composing Optional Value Functions with flatMap 8.7.7 Turning an Optional into a Stream 8.8 Collecting Results 8.9 Collecting into Maps 8.10 Grouping and Partitioning 8.11 Downstream Collectors 8.12 Reduction Operations 8.13 Primitive Type Streams 8.14 Parallel Streams Exercises 9 PROCESSING INPUT AND OUTPUT 9.1 Input/Output Streams, Readers, and Writers 9.1.1 Obtaining Streams 9.1.2 Reading Bytes 9.1.3 Writing Bytes 9.1.4 Character Encodings 9.1.5 Text Input 9.1.6 Text Output 9.1.7 Reading and Writing Binary Data 9.1.8 Random-Access Files 9.1.9 Memory-Mapped Files 9.1.10 File Locking 9.2 Paths, Files, and Directories 9.2.1 Paths 9.2.2 Creating Files and Directories 9.2.3 Copying, Moving, and Deleting Files 9.2.4 Visiting Directory Entries 9.2.5 ZIP File Systems 9.3 HTTP Connections 9.3.1 The URLConnection and HttpURLConnection Classes 9.3.2 The HTTP Client API 9.4 Regular Expressions 9.4.1 The Regular Expression Syntax 9.4.2 Testing a Match 9.4.3 Finding All Matches 9.4.4 Groups 9.4.5 Splitting along Delimiters 9.4.6 Replacing Matches 9.4.7 Flags 9.5 Serialization 9.5.1 The Serializable Interface 9.5.2 Transient Instance Variables 9.5.3 The readObject and writeObject Methods 9.5.4 The readExternal and writeExternal Methods 9.5.5 The readResolve and writeReplace Methods 9.5.6 Versioning 9.5.7 Deserialization and Security Exercises 10 CONCURRENT PROGRAMMING 10.1 Concurrent Tasks 10.1.1 Running Tasks 10.1.2 Futures 10.2 Asynchronous Computations 10.2.1 Completable Futures 10.2.2 Composing Completable Futures 10.2.3 Long-Running Tasks in User-Interface Callbacks 10.3 Thread Safety 10.3.1 Visibility 10.3.2 Race Conditions 10.3.3 Strategies for Safe Concurrency 10.3.4 Immutable Classes 10.4 Parallel Algorithms 10.4.1 Parallel Streams 10.4.2 Parallel Array Operations 10.5 Threadsafe Data Structures 10.5.1 Concurrent Hash Maps 10.5.2 Blocking Queues 10.5.3 Other Threadsafe Data Structures 10.6 Atomic Counters and Accumulators 10.7 Locks and Conditions 10.7.1 Locks 10.7.2 The synchronized Keyword 10.7.3 Waiting on Conditions 10.8 Threads 10.8.1 Starting a Thread 10.8.2 Thread Interruption 10.8.3 Thread-Local Variables 10.8.4 Miscellaneous Thread Properties 10.9 Processes 10.9.1 Building a Process 10.9.2 Running a Process 10.9.3 Process Handles Exercises 11 ANNOTATIONS 11.1 Using Annotations 11.1.1 Annotation Elements 11.1.2 Multiple and Repeated Annotations 11.1.3 Annotating Declarations 11.1.4 Annotating Type Uses 11.1.5 Making Receivers Explicit 11.2 Defining Annotations 11.3 Standard Annotations 11.3.1 Annotations for Compilation 11.3.2 Meta-Annotations 11.4 Processing Annotations at Runtime 11.5 Source-Level Annotation Processing 11.5.1 Annotation Processors 11.5.2 The Language Model API 11.5.3 Using Annotations to Generate Source Code Exercises 12 THE DATE AND TIME API 12.1 The Time Line 12.2 Local Dates 12.3 Date Adjusters 12.4 Local Time 12.5 Zoned Time 12.6 Formatting and Parsing 12.7 Interoperating with Legacy Code Exercises 13 INTERNATIONALIZATION 13.1 Locales 13.1.1 Specifying a Locale 13.1.2 The Default Locale 13.1.3 Display Names 13.2 Number Formats 13.3 Currencies 13.4 Date and Time Formatting 13.5 Collation and Normalization 13.6 Message Formatting 13.7 Resource Bundles 13.7.1 Organizing Resource Bundles 13.7.2 Bundle Classes 13.8 Character Encodings 13.9 Preferences Exercises 14 COMPILING AND SCRIPTING 14.1 The Compiler API 14.1.1 Invoking the Compiler 14.1.2 Launching a Compilation Task 14.1.3 Capturing Diagnostics 14.1.4 Reading Source Files from Memory 14.1.5 Writing Byte Codes to Memory 14.2 The Scripting API 14.2.1 Getting a Scripting Engine 14.2.2 Evaluating Scripts 14.2.3 Bindings 14.2.4 Redirecting Input and Output 14.2.5 Calling Scripting Functions and Methods 14.2.6 Compiling a Script Exercises 15 THE JAVA PLATFORM MODULE SYSTEM 15.1 The Module Concept 15.2 Naming Modules 15.3 The Modular “Hello, World!” Program 15.4 Requiring Modules 15.5 Exporting Packages 15.6 Modules and Reflective Access 15.7 Modular JARs 15.8 Automatic Modules 15.9 The Unnamed Module 15.10 Command-Line Flags for Migration 15.11 Transitive and Static Requirements 15.12 Qualified Exporting and Opening 15.13 Service Loading 15.14 Tools for Working with Modules Exercises Index