Java Cookbook: Problems and Solutions for Java Developers

Preface
   Who This Book Is For
   What’s in This Book?
   What’s Not in This Book
   Organization of This Book
   Java Books
   Conventions Used in This Book
   Using Code Examples
   O’Reilly Online Learning
   Comments and Questions
   Acknowledgments
1. Getting Started: Compiling and Running Java
   1.0. Introduction
   1.1. Hello, World: Compiling and Running Java with the Standard JDK
   1.2. Hello, World of Classless Main 21P
   1.3. Downloading and Using the Code Examples
   1.4. Compiling, Running, and Testing with an IDE
   1.5. Exploring Java with JShell 11
   1.6. Using CLASSPATH Effectively
   1.7. Documenting Classes with Javadoc
   1.8. Beyond Javadoc: Annotations/Metadata
   1.9. Packaging and Running JAR Files
   1.10. Creating a JAR That Supports Multiple Versions of Java
   1.11. Packaging Web Tier Components into a WAR File
   1.12. Compiling and Running Java: GraalVM for Better Performance
   1.13. Getting Information About the Environment, OS, and Runtime
2. Software Development, Testing, and Maintenance
   2.0. Introduction
   2.1. Designing Applications: Packages, Modules
   2.2. Using the Java Modules System
   2.3. Using JPMS to Create a Module
   2.4. Automating Compilation, Testing, and Deployment with Apache Maven
   2.5. Automating Compilation, Testing, and Deployment with Gradle
   2.6. Automating Dependency Management with Maven and Gradle
   2.7. Dealing with Deprecation Warnings
   2.8. Batch Refactoring for Warnings and Migrations
   2.9. Maintaining Code Correctness with Unit Testing: JUnit
   2.10. Isolating the Test Target with Mock Objects and Mockito
   2.11. Logging: Network or Local
   2.12. Setting Up SLF4J
   2.13. Network Logging with Log4j
   2.14. Network Logging with java.util.logging
   2.15. Maintaining Your Code with Continuous Integration
   2.16. Performance Timing
   2.17. Creating a Custom JDK Distribution with jlink
   2.18. Creating Platform-Specific Installers with jpackage
3. Strings and Things
   3.0. Introduction
   3.1. Taking Strings Apart with Substrings, Tokenizing, and Trimming Methods
   3.2. String Formatting with Formatter and printf()
   3.3. Building Strings with StringBuilder
   3.4. Processing a String One Character at a Time
   3.5. Aligning, Indenting, and Unindenting Strings
   3.6. Converting Between Unicode Characters and Strings
   3.7. Reversing a String by Word or by Character
   3.8. Expanding and Compressing Tabs
   3.9. Controlling Case
   3.10. Adding Nonprintable Characters into a String
   3.11. Creating a Message to the World with I18N Resources
   3.12. Using a Particular Locale
   3.13. Creating a Resource Bundle
   3.14. Program: A Simple Text Formatter
4. String Matching with Regular Expressions
   4.0. Introduction
   4.1. Regular Expression Syntax
   4.2. Checking If a String Matches a Regex
   4.3. Grouping: Specifying Parts of the Regex
   4.4. Finding the Matching Text
   4.5. Replacing the Matched Text
   4.6. Printing All Occurrences of a Pattern
   4.7. Controlling Case in Regular Expressions
   4.8. Matching Accented, or Composite, Characters
   4.9. Matching Newlines in Text
   4.10. Program: Full Grep
5. Numbers
   5.0. Introduction
   5.1. Checking Whether a String Is a Valid Number
   5.2. Converting Numbers to Objects and Vice Versa
   5.3. Taking a Fraction of an Integer Without Using Floating Point
   5.4. Working with Floating-Point Numbers
   5.5. Formatting Numbers
   5.6. Converting Among Binary, Octal, Decimal, and Hexadecimal
   5.7. Operating on a Range of Integers
   5.8. Formatting with Correct Plurals
   5.9. Generating Random Numbers
   5.10. Multiplying Matrices
   5.11. Optimizing Large Arithmetic Operations with Vector Operations 22C
   5.12. Using Complex Numbers
   5.13. Handling Very Large Numbers
   5.14. Program: TempConverter
6. Dates and Times
   6.0. Introduction
   6.1. Finding Today’s Date
   6.2. Formatting Dates and Times
   6.3. Converting Among Dates/Times and Epoch Seconds
   6.4. Parsing Strings into Dates
   6.5. Difference Between Two Dates
   6.6. Adding to or Subtracting from a Date
   6.7. Calculating Recurring Events
   6.8. Computing Dates Involving Time Zones
   6.9. Interfacing with Legacy Date and Calendar Classes
7. Structuring Data with Java
   7.0. Introduction
   7.1. Using Arrays for Data Structuring
   7.2. Resizing an Array
   7.3. Simplifying Array Handling with the Arrays Class
   7.4. The Collections Framework
   7.5. Lists: Like an Array, but More Dynamic
   7.6. Using Generic Types in Your Own Class: Stack Demo
   7.7. How Shall I Iterate Thee? Let Me Enumerate the Ways
   7.8. Avoiding Duplicate Values with a Set
   7.9. Mapping with Hashtable and HashMap
   7.10. Storing Strings in Properties and Preferences
   7.11. Sorting a Collection
   7.12. Finding an Object in a Collection
   7.13. Converting Between Collections and Arrays
   7.14. Making Your Own Data Structures Iterable
   7.15. Multidimensional Structures
8. Object-Oriented Techniques
   8.0. Introduction
   8.1. Object Methods: Formatting Objects with toString(), Comparing with Equals
   8.2. Constructor Simplification: Statements Before super(…​) 22P
   8.3. Using Inner Classes
   8.4. Simplifying Data Objects with Records (or Lombok)
   8.5. Providing Callbacks via Interfaces
   8.6. Polymorphism/Abstract Methods
   8.7. Improving Interfaces with Default, Static, and Private Methods
   8.8. Using Typesafe Enumerations
   8.9. Using Type Pattern Matching
   8.10. Avoiding NPEs with “Optional”
   8.11. Controlling Subclassing with Sealed Types 17
   8.12. Enforcing the Singleton Pattern
   8.13. Roll Your Own Exceptions
   8.14. Using Dependency Injection
   8.15. Combining Java Features for Data-Oriented Programming
9. Functional Programming Techniques: Functional Interfaces, Streams, and Parallel Collections
   9.0. Introduction
   9.1. Using Lambdas/Closures Instead of Inner Classes
   9.2. Using Predefined Lambda Interfaces or Rolling Your Own
   9.3. Simplifying Processing with Streams
   9.4. Simplifying Streams with Collectors
   9.5. Simplifying Streams with Stream Gatherers 22P
   9.6. Simplifying Streams with Your Own Stream Gatherer 22P
   9.7. Improving Throughput with Parallel Streams and Collections
   9.8. Using Existing Code as Functional with Method References
   9.9. Java Mixins: Mixing in Methods
   9.10. Functional Programming with Flow and Reactive Streams
10. Input and Output: Reading, Writing, and Directory Tricks
   10.0. Introduction
   10.1. Discovering Filesystem Paths
   10.2. Getting and Setting File and Directory Information: Files and Path
   10.3. Creating and Deleting Files or Directories
   10.4. Changing a File’s Name or Other Attributes
   10.5. About InputStreams/OutputStreams and Readers/Writers
   10.6. Reading and Writing Files
   10.7. Scanning Input with StreamTokenizer, Scanner, Parsers
   10.8. Reading from the Standard Input or from the Console/Controlling Terminal
   10.9. Copying a File
   10.10. Reassigning the Standard Streams
   10.11. Duplicating a Stream as It Is Written
   10.12. Reading/Writing a Different Character Set
   10.13. Those Pesky End-of-Line Characters
   10.14. Beware Platform-Dependent File Code
   10.15. Reading and Writing JAR or ZIP Archives
   10.16. Reading Files in a Filesystem-Neutral Way with getResource() and getResourceAsStream()
   10.17. Creating a Transient/Temporary File
   10.18. Getting the Directory Roots
   10.19. Using the File Watcher Service to Get Notified About File Changes
   10.20. Walking a File Tree (like Find)
11. Threaded Java
   11.0. Introduction
   11.1. Running Code in a Different Thread
   11.2. Using Virtual Threads for Better Performance
   11.3. Rendezvous and Timeouts
   11.4. Synchronizing Threads with the synchronized Keyword
   11.5. Simplifying Synchronization with Locks
   11.6. Locking with One Writer, Many Readers
   11.7. Sharing Data Among Threads—ThreadLocal and ScopedValue: Structuring Concurrency
   11.8. Simplifying Producer/Consumer with the Queue Interface
   11.9. Optimizing Parallel Processing with Fork/Join
   11.10. Scheduling Tasks: Future Times, Background Saving in an Editor
12. Data Science and R
   12.0. Introduction
   12.1. Using Data in Apache Spark
   12.2. Using R Interactively
   12.3. Comparing/Choosing an R Implementation
   12.4. Using R from Within a Java App: Renjin
   12.5. Using Java from Within an R Session
   12.6. Using R in a Web App
13. Machine Learning/Artificial Intelligence
   13.0. Introduction
   13.1. Some Major AI Software
   13.2. Using ChatGPT Directly
   13.3. Using ChatGPT via LangChain4j
   13.4. Making an AI Service with LangChain4j
   13.5. Conversing with Shadows
   13.6. Generating Images with LangChain4j
   13.7. Mixed Media Prompts: Inferences from Images with LangChain4j
   13.8. Running AI Locally with ollama
14. Network Clients
   14.0. Introduction
   14.1. HTTP/REST Web Client—Modern API 11
   14.2. Contacting a Socket Server
   14.3. Finding and Reporting Network Addresses
   14.4. Handling Network Errors
   14.5. Reading and Writing Textual Data
   14.6. Reading and Writing Binary or Serialized Data
   14.7. Postcards of the Internet: Using UDP Datagrams
   14.8. URI, URL, or URN?
   14.9. Program: Sockets-Based Chat Client
15. Server-Side Java
   15.0. Introduction
   15.1. Opening a Server Socket for Business
   15.2. Finding Network Interfaces
   15.3. Returning a Response (String or Binary)
   15.4. Handling Multiple Clients
   15.5. Serving the HTTP Protocol
   15.6. Securing a Web Server with TLS (formerly SSL) and JSSE
   15.7. Creating a REST Service/Microservice with JAX-RS
   15.8. Unix Domain Sockets—Even on Windows! 16
16. Processing JSON Data
   16.0. Introduction
   16.1. Generating JSON Directly
   16.2. Parsing and Writing JSON with Jackson
   16.3. Parsing and Writing JSON with org.json
   16.4. Parsing and Writing JSON with JSON-B
   16.5. Finding JSON Elements with JSON Pointer
17. Reflection, or “A Class Named Class”
   17.0. Introduction
   17.1. Loading and Instantiating a Class Dynamically
   17.2. Printing Class Information
   17.3. Getting a Class Descriptor
   17.4. Finding and Using Methods and Fields
   17.5. Invoking Class Members via MethodHandles
   17.6. Listing Classes in a Package
   17.7. Accessing Nested Members of Same Class
   17.8. Accessing Private Methods and Fields via Reflection
   17.9. Constructing a Class from Scratch with a ClassLoader
   17.10. Constructing a Class from Scratch with JavaCompiler
   17.11. Constructing or Modifying Class Files with the Class-File API 22P
   17.12. Using and Defining Annotations
   17.13. Finding Plug-In-Like Classes via Annotations
   17.14. A Timing Program
   17.15. Program: CrossRef
18. Using Java with Other Languages
   18.0. Introduction
   18.1. Running an External Program from Java
   18.2. Running a Program and Capturing Its Output
   18.3. Calling Other Languages via javax.script
   18.4. Mixing Languages with GraalVM 21
   18.5. Calling Between Java and Native Code with the Foreign Function and Memory API 22
   18.6. Calling Other Languages via Native Code (JNI)
   18.7. Calling Java from Native Code with JNI
Afterword
A. Java Then and Now
   Introduction: Always in Motion the Java Is
   What Was New in Java 16 16
   What Was New in Java 17 LTS 17
   What Was New in Java 18 18
   What Was New in Java 19 19
   What Was New in Java 20 20
   What Was New in Java 21 LTS 21
   What Was New in Java 22 22
   What’s New in Java 23 23
   What’s New in Java 24 24
   Looking Ahead
Index