book

Java in a Nutshell, 9th Edition

by Benjamin J. Evans, Jason R. Clark, David Flanagan

August 2026

Beginner to intermediate

538 pages

14h 40m

English

O'Reilly Media, Inc.

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Includes

Quizzes

Sandbox

Foreword
Preface
Changes in the Ninth EditionContents of This BookRelated BooksConventions Used in This BookUsing Code ExamplesO’Reilly Online LearningHow to Contact UsAcknowledgments
I. Introducing Java
1. Introduction to the Java Environment
The Language, the JVM, and the EcosystemWhat Is the Java Language?What Is the JVM?What Is the Java Ecosystem?The Lifecycle of a Java ProgramFrequently Asked QuestionsComparing Java to Other LanguagesJava Compared to PythonJava Compared to JavaScriptJava Compared to CJava Compared to C++Answering Some Criticisms of JavaOverly VerboseSlow to ChangePerformance ProblemsInsecureToo CorporateA Brief History of Java and the JVMJava’s Release ModelSummary
2. Java Syntax from the Ground Up
Java Programs from the Top DownLexical StructureThe Unicode Character SetCase Sensitivity and WhitespaceCommentsReserved WordsIdentifiersLiteralsPunctuationPrimitive Data TypesThe boolean TypeThe char TypeInteger TypesFloating-Point TypesPrimitive Type ConversionsExpressions and OperatorsOperator SummaryArithmetic OperatorsString Concatenation OperatorIncrement and Decrement OperatorsComparison OperatorsBoolean OperatorsBitwise and Shift OperatorsAssignment OperatorsThe Conditional OperatorThe instanceof OperatorPattern Matching and Type PatternsSpecial OperatorsStatementsExpression StatementsCompound StatementsThe Empty StatementLabeled StatementsLocal Variable Declaration StatementsThe if/else StatementThe switch StatementThe switch ExpressionThe while StatementThe do StatementThe for StatementThe foreach VariantThe break StatementThe continue StatementThe return StatementThe synchronized StatementThe throw StatementThe try/catch/finally StatementThe try-with-resources StatementThe assert StatementMethodsDefining MethodsMethod ModifiersChecked and Unchecked ExceptionsVariable-Length Argument ListsIntroduction to Classes and ObjectsDefining a ClassCreating an ObjectUsing an ObjectObject LiteralsLambda ExpressionsArraysArray TypesCreating and Initializing ArraysUsing ArraysMultidimensional ArraysReference TypesReference Versus Primitive TypesManipulating Objects and Reference CopiesComparing ObjectsBoxing and Unboxing ConversionsPackages and the Java NamespacePackage DeclarationGlobally Unique Package NamesImporting TypesImporting Static MembersSummary
3. Your First Java Programs
Introduction to JShellSimple Standalone Java ProgramsJava Source File StructureThe Source Code CompilerExecuting Full Java ProgramsSummary
4. Object-Oriented Programming in Java
Overview of Classes and RecordsBasic OO DefinitionsRecordsInterfacesOther Reference TypesClass Definition SyntaxFields and MethodsField Declaration SyntaxClass FieldsClass MethodsInstance FieldsInstance MethodsHow the this Reference WorksCreating and Initializing ObjectsDefining a ConstructorDefining Multiple ConstructorsInvoking One Constructor from AnotherField Defaults and InitializersRecord ConstructorsSubclasses and InheritanceExtending a ClassSuperclasses, Object, and the Class HierarchySubclass ConstructorsConstructor ChainingThe Default ConstructorHiding Superclass FieldsOverriding Superclass MethodsSealed ClassesData Hiding and EncapsulationAccess ControlData Accessor MethodsAbstract Classes and MethodsReference Type ConversionsModifier SummarySummary
5. The Java Type System
InterfacesDefining an InterfaceExtending InterfacesImplementing an InterfaceRecords and InterfacesSealed InterfacesDefault MethodsMarker InterfacesJava GenericsIntroduction to GenericsGeneric Types and Type ParametersDiamond SyntaxType ErasureBounded Type ParametersIntroducing CovarianceWildcardsGeneric MethodsCompile and Runtime TypingUsing and Designing Generic TypesEnums and AnnotationsEnumsAnnotationsLambda ExpressionsLambda Expression ConversionMethod ReferencesLambdas and Functional ProgrammingLexical Scoping and Local VariablesNested TypesStatic Member TypesNonstatic Member ClassesLocal ClassesAnonymous ClassesDescribing the Java Type SystemType InferenceNominal TypingAn Aside: Nondenotable TypesSummary
6. Introduction to Object-Oriented Design in Java
Java ValuesIs Java “Pass-by-Reference”?ConstantsImportant Common MethodstoString()equals()hashCode()Comparable::compareTo()clone()Working with Fields and Object StateField InheritanceAccessorsMutability and ImmutabilityConstruction PatternsFactory MethodsBuildersConstructor ProloguesSingletonInstance Methods or Class Methods?Exceptions and Exception HandlingInterfaces Versus Abstract ClassesPartial ImplementationsDo Default Methods Change Java’s Inheritance Model?DelegationModern OOD in JavaOOD Using LambdasOOD Using RecordsOOD Using Sealed TypesPattern MatchingSafe Java ProgrammingCase Study: Circle-Ellipse ProblemSummary
II. Working with the Java Platform

7. Programming and Documentation Conventions
Naming and Capitalization ConventionsPractical NamingJava Documentation CommentsStructure of a Doc CommentFormatting Multiline Doc CommentsFormatting Markdown Doc CommentsDoc-Comment TagsInline Doc-Comment TagsCross-References in Doc CommentsDoc Comments for PackagesDocletsConventions for Portable ProgramsSummary
8. Working with Java Collections
Introduction to Collections APICreating CollectionsThe Collection InterfaceThe List InterfaceThe Map InterfaceThe Set InterfaceMutability and Immutability RevisitedJava Streams and Lambda ExpressionsThe Streams APIFunctional ApproachesUtility MethodsArrays and Helper MethodsSummary
9. Java and Memory
Basic Concepts of Automatic Memory ManagementIntroducing Mark-and-SweepExactness and Limitations of Naive Mark-and-SweepImproving on Basic Garbage CollectionThe Weak Generational HypothesisEvacuationThe HotSpot HeapG1Alternate CollectorsParallelOldSerialShenandoahZGCSummary
10. Handling Common Data Formats
TextSpecial Syntax for StringsString ImmutabilityString FormattingRegular ExpressionsNumbers and MathHow Java Represents Integer TypesJava and Floating-Point NumbersJava’s Standard Library of Mathematical FunctionsDate and TimeIntroducing the Java 8 Date and Time APIQueriesAdjustersTime ZonesLegacy Date and TimeSummary
11. File Handling and I/O
PathFilesFileSystemI/O StreamsReaders and WritersDecoratorstry-with-resources RevisitedClassic Java I/ONIO Channels and BuffersByteBufferMapped Byte BuffersAsync I/OFuture-Based StyleCallback-Based StyleWatch Services and Directory SearchingNetworkingHTTPTCPIPSummary
12. Concurrency in Java
Basic Concepts of Java ConcurrencyThread LifecycleVisibility and MutabilityConcurrent SafetyProtecting State with ExclusionVolatile StateWorking with ThreadsUseful Methods of ThreadDangerous Methods of ThreadIndefinite WaitingSynchronization ChecklistConcurrent Data StructuresAtomic CountersConcurrent MapsQueues and BlockingQueuesExecutors and ThreadpoolsVirtual ThreadsSummary
13. Classloading, Reflection, and Method Handles
Class Files, Class Objects, and MetadataExamples of Class ObjectsClass Objects and MetadataPhases of ClassloadingLoadingVerificationPreparation and ResolutionInitializationSecure Programming and ClassloadingApplied ClassloadingClassloader HierarchyReflectionWhen to Use ReflectionHow to Use ReflectionMethod HandlesMethodTypeMethod LookupInvoking Method HandlesSummary
14. Java Platform Modules
Why Modules?Modularizing the JDKThe Java SE Module GraphModule ImportsWriting Your Own ModulesBasic Modules SyntaxBuilding a Simple Modular ApplicationThe Module PathAutomatic ModulesOpen ModulesProviding ServicesMigrating to ModulesMulti-Release JARsConverting to a Multi-Release JARCustom Runtime ImagesIssues with ModulesLack of VersioningThe Unsafe ClassAdoption RatesSummary
A. Future Java
Long-Term JDK ProjectsPanamaValhallaLeyden and Cloud Native JavaIntegrity By Default
B. Platform Tools
Command-Line ToolsIntroduction to Java Flight Recorder (JFR)
Index
About the Authors

Overview

Java in a Nutshell doesn't just help experienced Java programmers get the most out of versions through Java 25. It also provides a learning path for new developers. Chock-full of examples that demonstrate how to take complete advantage of modern Java APIs and development best practices, this thoroughly revised guide includes new material on recent enhancements to Java.

The first section provides a fast-paced, no-fluff introduction to the Java programming language and the chief runtime aspects of the Java platform. The second section explores core concepts and APIs and explains how to perform real programming work in the Java environment.

This updated 9th edition includes an entirely new chapter dedicated to Java 25's groundbreaking Compact Source Files and Instance Main Methods feature, which makes the language more accessible than ever for beginners. It also features an interactive Java sandbox for hands-on practice.

Get up to speed on language details through Java 25, including the latest LTS release
Master Java's new beginner-friendly features like Compact Source Files and Instance Main Methods
Learn object-oriented programming using modern Java syntax
Practice with the interactive Java sandbox to reinforce key concepts
Explore generics, lambda expressions, sealed types, and records
Understand techniques used in object-oriented design
Examine memory and concurrency, including Java 25's virtual threads
Work with Java collections and handle common data formats
Become familiar with development tools in OpenJDK

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