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, Fourth Edition, is a complete yet concise guide that reflects all changes through Java SE 21, 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 21, 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.

 This book is fully updated to Java 21. It uses modern features and does not dwell on historical or obsolete constructs. Preview features that may make it to the language in the future are not covered either. A key reason to use Java is to tackle concurrent programming. With parallel algorithms and threadsafe data structures readily available in the Java library, the way application programmers should handle concurrent programming has completely changed. I provide fresh coverage, showing you how to use the powerful library features instead of error-prone low-level constructs.

 Traditionally, books on Java have focused on user interface programming, but nowadays, few developers produce user interfaces on desktop computers. You will be able to use this book effectively without being distracted by lengthy GUI code. Finally, this book is written for application programmers, not for a college course and not for systems wizards. The book covers issues that application programmers need to wrestle with, such as logging and working with files, but you won’t learn how to implement a linked list by hand or how to write a web server.

• 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 structured techniques, threadsafe data structures, and virtual threads for effective concurrent programming
• 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