Slides from talk at Java Forum Stuttgart in July 2023

1. Modern Java
Ron Veen
Java Forum Stuttgart 2023

2. Who is Ron Veen
@ronveen
ronveen
@ronveen@foojay.social
● Java developer for 20+ years
● Special Agent @ Team Rockstars IT
● Writing a book about Migrating to cloud-native Jakarta EE

3. Agenda
1. Virtual threads, structured concurrency, scoped values
2. What else is in Java 21
3. Records, sealed classes and pattern matching
4. Examples of data-oriented programming with Java

4. Part 1 - Virtual Threads, Structured Concurreny, Scoped Values

5. Java Threads

6. Virtual Threads

7. Factory methods

8. Virtual Thread Per Task Executor

9. Structured Concurrency

10. Invoke All pattern

11. Invoke Any pattern

12. Thread Locals
1. Share information between different components of your application
2. Create a ThreadLocal instance that is reachable from anywhere
3. You can provide an initial value on creation
4. Or set a value using set (T value)
5. Retrieve the value anywhere via get( )

13. The problem with Thread Locals
1. Mutable
2. Resource intensive
3. Leaking

14. Enter Scoped Values
1. Exist for a limited time (lifetime of the Runnable)
2. Only the thread that wrote the value can read it
3. Immutable
4. Passed by reference

15. Scoped Values

16. Part 2 - What else is in Java 21

17. Agenda
1. Simpler main methods
2. Unnamed classes
3. Unnamed variables
4. Sequenced Collections
5. String Templates

18. Simpler main methods

19. Unnamed classes

20. Unnamed variables

21. Unnamed variables

22. Unnamed variables

23. Sequenced Collections

24. Sequenced Collections

25. String templates

26. String templates

27. String templates

28. Part 3 - Records, sealed classes and pattern matching

29. Modern Java support for data-oriented programming
● Records
● Sealed classes
● Pattern matching
● Switch functions for pattern matching

30. Records

31. Sealed classes

32. Pattern Matching
● Predicate
● Object to test against
● Pattern variables
● Flow scope

33. Pattern Matching: Instanceof
● Predicate ==> instanceof Approver
● Object to test against ==> user
● Pattern variables ==> a
● Flow scope ==> between { }

34. Pattern Matching: switch

35. Pattern Matching: record

36. Part 4 - Combining Java and data-oriented programming

37. Data-oriented programming

38. Principles of data-oriented programming
● Separate data from logic
● Data is stored in generic data structures
● Data is immutable

39. Alternative optional

40. Usage of data-oriented programming

41. Summary
● Data-oriented programming treats data as first-class citizens
● Data drives your application
● Java supports data-oriented programming via records, sealed classes and pattern matching

42. Questions