This is the version of the talk given after the Java 9 release

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

2. Real World Java 9

3. Real World Java 9
• Jigsaw in Action

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

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

6. Why Java 9?

7. 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

8. Jigsaw

9. REPL

10. And… other things?

12. 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

13. The Case Study

14. Twitter Dashboard

16. http://bit.ly/Java8InAnger

17. Compiling with Java 9

18. Jigsaw

19. • 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

20. Java Platform Module
System (JPMS)

32. module-info.java

33. Pain

34. Pain
• Some structural reorganisation may be
needed

35. Pain
• Some structural reorganisation may be
needed
• IDE support is not what we’re used to

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

37. Gain

38. • Cleaner design
Gain

39. • Cleaner design
• Reliable configuration
Gain

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

41. Reactive API

42. Reactive Streams API

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

44. Java 9 Flow API

46. Other Java 9 Features

47. 269: Convenience Factory Methods
for Collections

48. 213: Private Methods on Interfaces

49. New Methods on the Streams API

50. New Methods on Optional

51. 259: Stack-Walking API

52. 102: Process API Updates

53. 238: Multi-Release JAR Files

54. 277: Updated Deprecation

55. 224: HTML5 Javadoc

56. 225: Javadoc search

59. JShell (REPL)

60. https://docs.oracle.com/javase/9/
jshell/introduction-jshell.htm

61. We’d Love Your Help

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

63. The Pain

64. Your code might break!

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

66. • 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

67. • 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

68. Tools are still evolving

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

70. Don’t rush in to modularisation

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

72. The Gain

73. Encourages good design

74. Encourages new ways of working

75. Just a bit nicer to write code

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

77. http://bit.ly/RealJava9