The feature we always hear about whenever Java 9 is in the news is Jigsaw, modularity. But this doesn't scratch the same developer itch that Java 8's lambdas and streams did, and we're left with a vague sensation that the next version might not be that interesting. Java 9 actually has a lot of great additions and changes to make development a bit nicer. These features can't be lumped under an umbrella term like Java 8's lambdas and streams, the changes are scattered throughout the APIs and language features that we regularly use. In this presentation Trisha will show, via live coding: - What the Java Platform Module System is and how to make your code modular - How we can use the new Flow API to utilise Reactive Programming - The improvements to the Streams API that make it easier to control infinite streams - How to the Collections convenience methods simplify code Along the way we'll bump into other Java 9 features, including some of the additions to interfaces and changes to deprecation.

1. —
Trisha Gee (@trisha_gee)
Developer & Technical Advocate, JetBrains
Real World Java
9

2. Any questions?
Use the Questions pane in the GoToWebinar window. We’ll try to answer as we go along.

4. Real World Java 9
• Jigsaw in Action
• The Reactive API in Java 9
• Everything Else

5. Why Java 9?

6. Free Lunch!
• Better Use of Memory
• Better Performance of:
• Locking
• Secure Apps
• Graphics
• Better Use of Hardware
• Better Documentation
• Prettier Graphics (Windows and Linux)
• Faster Compilation

7. Jigsaw

8. REPL

9. And… other things?

10. 274: Enhanced Method Handles
275: Modular Java Application Packaging
276: Dynamic Linking of Language-Defined Object Models
277: Enhanced Deprecation
278: Additional Tests for Humongous Objects in G1
279: Improve Test-Failure Troubleshooting
280: Indify String Concatenation
281: HotSpot C++ Unit-Test Framework
282: jlink: The Java Linker
283: Enable GTK 3 on Linux
284: New HotSpot Build System
285: Spin-Wait Hints
287: SHA-3 Hash Algorithms
288: Disable SHA-1 Certificates
289: Deprecate the Applet API
290: Filter Incoming Serialization Data
292: Implement Selected ECMAScript 6 Features in Nashorn
294: Linux/s390x Port
295: Ahead-of-Time Compilation
297: Unified arm32/arm64 Port
298: Remove Demos and Samples

11. The Case Study

12. Twitter Dashboard

14. http://bit.ly/Java8InAnger

15. Compiling with Java 9

16. Jigsaw

17. • JEP 200: The Modular JDK
• JEP 201: Modular Source Code
• JEP 220: Modular Run-Time Images
• JEP 260: Encapsulate Most Internal APIs
• JEP 261: Module System
• JEP 282: jlink: The Java Linker
• JSR 376: Java Platform Module System
Project Jigsaw

18. Java Platform Module System
(JPMS)

23. module-info.java

24. Pain
• Some structural reorganisation may be needed
• IDE support is not what we’re used to
• RTFM. No, really do.

25. • Cleaner design
• Reliable configuration
• Smaller deployables
Gain

26. Reactive API

27. Reactive Streams API

28. • Akka Streams
• MongoDB Reactive Java Driver
• Ratpack
• Reactive Rabbit
• Reactor
• RxJava
• Vert.x
Implementations

29. Java 9 Flow API

31. Other Java 9 Features

32. 269: Convenience Factory Methods
for Collections

33. 213: Private Methods on Interfaces

34. New Methods on the Streams API

35. New Methods on Optional

36. 259: Stack-Walking API

37. 102: Process API Updates

38. 238: Multi-Release JAR Files

39. 277: Updated Deprecation

40. 224: HTML5 Javadoc

41. 225: Javadoc search

43. JShell (REPL)

44. https://docs.oracle.com/javase/9/jshell/int
roduction-jshell.htm

45. We’d Love Your Help
https://youtrack.jetbrains.com/issue/IDEA-
161611

46. The Pain

47. Your code might break!
Try it out now to find out sooner, not later

48. • 214: Remove Deprecated GC Combinations
• 231: Remove Launch-Time JRE Version Selection
• 240: Remove the JVM TI hprof Agent
• 241: Remove the jhat Tool
• 260: Encapsulate Most Internal APIs
• 289: Deprecate the Applet API
• 298: Remove Demos and Samples
Going Away

49. • 158: Unified JVM Logging
• 223: New Version-String Scheme
• 245: Validate JVM Command-Line Flag Arguments
• 248: Make G1 the Default Garbage Collector
• 271: Unified GC Logging
Possible Unexpected Behaviour

50. Tools are still evolving
…another reason to try it early

51. Don’t rush in to modularisation
It might not be for you

52. The Gain

53. Encourages good design

54. Encourages new ways of working

55. Just a bit nicer to write code

56. …and you’ll be ready for Java 10
Or 18.3…

57. http://bit.ly/RealJava9