Your Java isn't the same

This deck covers some of the JDK changes between versions 9 to 21.

Transcript

1. Your Java isn't Your Java isn't the same the same Rodrigo Graciano / Paula Santana
2. About Backend Developer MVP Microsoft JUG Leader @DevsJavaGirl Paula Santana Java Champion Ace PRO JCP EC Member JUG Leader @NYJavaSIG Director of Data Engineering Rodrigo Graciano
3. Topics Some information Features about developer Experience GC's and Performance What's next 01 02 03 04
4. 1- Some Information 1- Some Information
5. 60% 48% 30% Java 8 Versions in Production Java 11 Java 17 https://www.jetbrains.com/lp/devecosystem-2022/java/
6. Versions LTS Mar 2014 Sep 2018 Sep 2021 Sep 2023 8 11 17 21
7. Projects Loom Panama Amber Project Amber is to explore and incubate smaller, productivity-oriented Java language features explore and incubate Java VM features and APIs built on top of them for the implementation of lightweight user-mode threads (fibers), delimited continuations (of some form), and related features, such as explicit tail-call. improving and enriching the connections between the Java virtual machine and well-defined but “foreign” (non-Java) APIs, including many interfaces commonly used by C programmers. Valhalla Project Valhalla is augmenting the Java object model with value objects and user-defined primitives, combining the abstractions of object-oriented programming with the performance characteristics of simple primitives
8. 2- Features about developer Experience 2- Features about developer Experience
9. Local-Variable Local-Variable Type Inference Type Inference Java 10
10. Before
11. After
12. more
13. Local-Variable Syntax Local-Variable Syntax for Lambda Parameters for Lambda Parameters Java 11
14. Before After
15. more
16. don't do that
17. Switch Expressions Switch Expressions Java 12 - Preview Java 13 - Second Preview Java 14 - released --enable-preview
18. Before
19. After
20. Yield
21. don't do that
22. Text Blocks Text Blocks Java 12 - Preview Java 13 - second Preview Java 14 - released
23. start and end with a “”” (three double-quote marks) followed by optional white spaces and a newline. It allows us to include literal fragments of HTML, JSON, SQL, or whatever we need, in a more elegant and readable way.
24. Before Required significant editing with escapes and concatenation The snippet was often difficult to read and arduous to maintain.
25. After The result type of a text block is still a String. Text blocks just give us another way to write String .
26. More The content may include line terminators directly. So in this example, both are equivalent. If we need carriage returns (\r) to be present, we have to explicitly add them to the text block if you use identation, use the position of closing triple quotes relative to the position of the last line
27. Pay attention USE TEXT BLOCK TO CLARIFY THE CODE, SPECIALLY IN MULTIPLE LINE STRINGS IF THE CONTENT IS SHORT, PREFER TO USE STRINGS AVOID USING TEXT BLOCKS INSIDE OF COMPLEX EXPRESSIONS, LIKE LAMBDA
28. Pattern Matching for Pattern Matching for instanceof instanceof Java 14 - Preview Java 15 - second Preview Java 16 - released
29. Before
30. After
31. Helpful Helpful NullPointerExceptions NullPointerExceptions Java 14
32. Cast the first stone who never received a NullPointerException
33. Before After
34. The filename and line number do not pinpoint exactly which variable was null
35. Before After
36. Records Records Java 14 - Preview Java 15 - Second Preview Java 16 - Released
37. Before
38. After Is Final Not Serializable by default No Setters getId() -> id()
39. Sealed Classes Sealed Classes Java 15 - Preview Java 16 - Second Preview Java 17 - Released
40. PROVIDE a more declarative way than access modifiers to restrict the use of a superclass. THE PURPOSE A SEALED class or interface can be extended or implemented only by those classes and interfaces permitted to do so. of sealing a class is to let client code reason clearly and conclusively about all permitted subclasses.
41. non-sealed A permitted subclass may also be declared sealed. However, if we declare it non-sealed, then it is open for extension:
42. Pattern Matching for switch (the saga) Pattern Matching for switch (the saga) Java 17 - Preview Java 18 - Second Preview Java 19 - Third Preview Java 20 - Fourth Preview Java 21 - Final season
43. wow
44. Sealed Class
45. Record Pattern Record Pattern Java 19 - Preview Java 20 - Second Preview Java 21 - released
46. Type Patterns remove many occurrences of casting at a stroke THE FIRST step towards a more declarative, data-focused style of programming.
47. Replace the type of variables Extract values of the pattern variable location into variables using pattern matching It's possible to
48. 3- what's next 3- what's next
49. String Templates String Templates Java 21 - Preview
50. Template expressions are a new kind of expression in the Java programming language. Template expressions can perform string interpolation but are also programmable in a way that helps developers compose strings safely and efficiently. Consists of: A template processor (STR); A dot character (U+002E), as seen in other kinds of expressions; and A template ("My name is \{name}") which contains an embedded expression (\{name}).
51. It may consist of Strings Perform Arithmetic invoke methods and access fields
52. Multi-line template expressions
53. Unnamed Classes and Instance Main Methods Unnamed Classes and Instance Main Methods Java 21 - Preview
54. With these changes, we can now write Hello, World! as: Top-level members or using fields are interpreted as members of the unnamed class. and run as:
55. Sequenced Collections Sequenced Collections Java 21 - Preview
56. Java’s collections framework lacks a collection type that represents a sequence of elements with a defined encounter order. It also lacks a uniform set of operations that apply across such collections. The problem.
57. About this feature New family of interfaces that represent the concept of a collection whose elements are arranged in a well-defined sequence or ordering, as a structural property of the collection.
58. Introduce new interfaces to represent collections with a defined encounter order and provide uniform APIs for accessing their first and last elements and processing them in reverse order. The framework will become more intuitive and efficient for developers.
59. 4- GC's and Performance 4- GC's and Performance
60. ZGC Shenandoah Epsilon No-op collector Perfect for benchmarking Allocate memory but does not recycle it Low-latency Works with all sizes of heaps – From small to Terabytes Pause time must not exceed 10ms Not a replacement for G1 Shenandoah is the low pause time garbage collector that reduces GC pause times by performing more garbage collection work concurrently with the running Java program G1 Enhance to G1. Automatically return Java heap memory to the operating system when idle Garbage Collectors Don't let the JVM pick your GC
61. Any questions? @psanrosa13 @rodrigograciano