Java 21: New Features and Enhancements

Learn to install and manage Java 21 with sdkman, including listing candidates, installing specific identifiers, and verifying versions across Unix and Windows.

Install and configure sdkman on Mac to manage multiple sdk versions, then install and verify Java 21 with sdk commands.

Learn to set up visual studio code for java development, install the java extension pack, and configure language support, debugger, test runner, project manager, and maven.

Explore the OpenJDK JDK 21 features page, comparing preview and final JEP implementations, including string templates, sequence collections, generational z gc, record patterns, pattern matching, and structured concurrency.

Explore unnamed classes and instance main methods in Java 21 preview for a minimal entry point and hello java output. Learn to enable preview features and compile with release 21.

Explore pattern matching for switch in Java 21, simplifying type checks and typecasting for a safer, more readable data driven code with a hands-on example.

Explore unnamed patterns and variables in Java 21, showing how ignoring unused details improves readability, reduces boilerplate, and prevents unused variable warnings.

Explore unnamed patterns and variables through a hands-on Java 21 example using a sealed shape interface with circle and rectangle records, and learn how to simplify code by using patterns.

Paolo invites you to leave a review if you enjoy the course, and to post questions in the discussion board; he and peers will answer them, fostering a discussion group.

Explore string templates in Java 21, improving over verbose string builders and formatters. Learn how template processors and dot syntax embed variables to create concise, maintainable strings.

Explore how Java 21's string template processor enables concise string interpolation of variables and methods, replacing verbose concatenation with expressions that include dates and arithmetic.

Explore Java 21's sequenced collections, including sequenced set and map, with add first/last, get first/last, reverse, and end-to-end removal demonstrated on an array list.

Demonstrate using the sequenced set with a linked hash set to add, remove, print, and reverse elements, with the reversed method returning a sequenced set and first and last values.

Explore sequenced map concepts in Java 21, using LinkedHashMap and default methods to manage map entries by encounter order with first and last entry operations.

Explore record patterns in Java 21, learn how destructuring records simplifies data extraction, reduces boilerplate, and enables direct use of name and age in pattern matching.

Explore how Java records simplify modeling an e-commerce domain by defining customer, product, and order records, calculating totals from order items, and updating order status with an enum.

Master record deconstructors in Java 21 by learning how to destructure records to extract fields like name and age, using pattern matching to access data inside an if statement.

Demonstrates component matching in record patterns by showing that a pattern variable’s type can align with record components, use var names, and avoid conflicts with flexible naming.

Explore nested patterns in Java 21 by deconstructing complex records with record patterns, pattern matching, and component extraction for name and address fields.

Learn how Java 21's switch supports record patterns and destructuring to match and extract fields like first name, last name, and age directly in switch statements.

Explore the advantages of record patterns for Java 21, including clarity and conciseness, immutability, and reduced boilerplate with auto-generated methods like equals, hashCode, toString, and component accessors.

Enhance garbage collection with Generational ZGC by focusing on the young generation to boost throughput, reduce latency, and explain young and old generations with plans to make it default GC.

Compare JVM-managed virtual threads with OS-managed platform threads in Java. Use virtual threads for high-concurrency, non-blocking I/O apps like web servers to improve scalability.

Explore virtual threads in Java 21 with a hands-on comparison of virtual versus platform threads, including 50,000 iterations, to see JVM-managed speed differences and OS-managed trade-offs.

Learn how scoped values simplify data sharing across a thread execution path, avoiding extra parameters and thread locals, with initialization, binding, and practical web logging context.

Learn to create a static final scoped value of type string in Java 21, and use run where to set and print it within a task, including virtual threads.

Explore the scoped value use case in Java 21, creating a current user scoped value, and running a task definition with a virtual thread that accesses the current user.

Leverage Java's vector API incubator to express computations that compile to SIMD instructions. Enhance performance with portability and graceful degradation, applicable to linear algebra, image processing, and character decoding.

Explore the Java 21 vector API by performing int vector additions using a specific vector species and producing a result array, while running via the JDK incubator vector module.