Real World Java 9
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See: https://trishagee.github.io/presentation/real_world_java_9/ In this presentation Trisha will show, via live coding: - How we can use the new Flow API to utilise Reactive Programming - How the improvements to the Streams API make it easier to control real-time streaming data - 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. We’ll see that once you start using Java 9, you can’t go back to Before.
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Real World Java 9
- 1. — Trisha Gee (@trisha_gee) Developer & Technical Advocate, JetBrains Real World Java 9
- 2. Real World Java 9 • Jigsaw in Action • Reactive Programming in Java 9 • The Other Good Stuff
- 3. Why Java 9?
- 4. 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
- 5. Jigsaw
- 6. REPL
- 8. 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
- 10. Java 9 in Production?
- 11. Everything is EA
- 12. Best Practice?
- 13. The Case Study
- 17. Compiling with Java 9
- 18. Jigsaw
- 25. module-info.java
- 26. Pain • Gradle not working • Reorganising the file structure is non-trivial • This project has no command-line build • IDE support is not what we’re used to • RTFM. No, really do.
- 27. Reactive API
- 29. • Akka Streams • MongoDB Reactive Java Driver • Ratpack • Reactive Rabbit • Reactor • RxJava • Vert.x Implementations
- 30. Java 9 Flow API
- 32. Where to use it?
- 52. Java 8 vs Reactive
- 55. • Work with multiple streams • Have multiple consumers • Backpressure • Very different concurrency model Reactive
- 56. Other Java 9 Features
- 57. 269: Convenience Factory Methods for Collections
- 58. 213: Private Methods on Interfaces
- 59. New Methods on the Streams API
- 61. 238: Multi-Release JAR Files
- 62. 102: Process API Updates
- 67. JShell (REPL)
- 69. We’d Love Your Help https://youtrack.jetbrains.com/issue/IDEA- 161611
- 70. The Pain
- 71. Your code might break! Try it out now to find out sooner, not later
- 72. • 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
- 73. • 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
- 74. Java 9 is still evolving So are the tools we use
- 75. Don’t rush in to modularisation It might not be for you
- 76. Reactive Streams are not the same as Java 8 Streams Different behaviour, different use cases
- 77. The Gain
- 79. Encourages new ways of working
- 80. Just a bit nicer to write code
Editor's Notes
- Show the working application
- Firstly, show IntelliJ working perfectly fine with JDK 9 Show “sense” at the Java 8 level compiling with Java 9 Will have some missing pieces Can’t use underscores THIS SECTION IS ABOUT ERRORS THAT MIGHT NOW BE IN YOUR CODE
- Started with Gradle Structure Ended up with this
- JDK 9
- Not using Gradle (couldn’t get it to work) Cheated with the tests Managing the dependencies with IDEA Not running from the command line (tests aren’t in modules) Realised my modules were all wrong And that modules != services Also, when creating these slides, realised it’s still wrong because the other services shouldn’t depend upon Twitter
- Support in the IDE: - doesn’t error - can create module-info files - basic code completion: * requires, plus completion for jdk modules * exports, plus completion for module names * opens… to… and completion - suggests adding “requires” lines - manually have to add exports
- Basically the same thing, but instead of injecting a function into some arbitrary position (which mine was), gives much more clarity to the end points and their jobs
- Picture of User Service
- Picture of what mood service does – with tweet coming in and CSV going out per tweet
- Update picture to show a mood comes out for every moody word, or no message if nothing Note that flat map needs the concurrency setting
- Picture of what mood service does – with tweet coming in and CSV going out per tweet
- Was actually a bit easier to test, because I was mocking out publishers and subscribers
- Oxymoron Annotation params No warning on imports Wish the param had been called “doomed”
- Can generate inside IntelliJ with… -html5
- Including camel case search http://download.java.net/java/jdk9/docs/api/overview-summary.html
- https://youtrack.jetbrains.com/issue/IDEA-161611 Please do give us feedback
- Defaults (GC) changing, validation being added, tools removed, internal APIs being hidden, logging messages changing
- Gradle, Groovy not working for me
- You can make use of the modules in the JDK, but you don’t need to apply it everywhere
- Backpressure; errors; implementing your own APIs
- Modules, separation of concerns
- REPL, Reactive
- All the other features