Introduction to Java 7 (Devoxx Nov/2011)

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Part 1/3 of our Devoxx University session. An introduction to some of the features of Java 7!

We're still working out where to host the torrent of our Virtual Box image with the coding exercises, we'll update the description when we sort it out.

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Introduction to Java 7 (Devoxx Nov/2011)

  1. 1. The WGJD - Intro to Java 7 Ben Evans and Martijn Verburg (@kittylyst @karianna) http://www.teamsparq.net Slide Design by http://www.kerrykenneally.comSaturday, 24 December 11 1
  2. 2. This is not an Oracle legal slide 2Saturday, 24 December 11 2
  3. 3. No, we’re not in sales! • Directors of TeamSparq – “Optimisation for Technical Teams” – Ben is known for his performance & concurrency work – Martijn is the “Diabolical Developer” and Ben can be just as ‘evil’ • Authors of “The Well-Grounded Java Developer” • Co-Leaders of the LJC (London’s Java User Group) – Hold a seat on the JCP SE/EE Executive Committee • Regular conference speakers – JavaOne, Devoxx, OSCON, etc 3Saturday, 24 December 11 3
  4. 4. Who are these two anyway? 4Saturday, 24 December 11 4
  5. 5. How this university session is going to work • This is a fact! – This is an opinion • This session may be a little different to advertised... – Being a “Well-Grounded Java Developer” changes over time • This session will go fairly quickly – But the slides will be made available – And you can always get hold of us for any questions 5Saturday, 24 December 11 5
  6. 6. Timetable • Introduction to Java 7 (~35 mins) • BREAK (5 minutes) • Polyglot and functional programming (~50 mins) • BREAK (5 minutes) • Modern Java Concurrency (~60 mins) • Conclusion and Extra Q&A 6Saturday, 24 December 11 6
  7. 7. Real Developers code through bathroom breaks 7Saturday, 24 December 11 7
  8. 8. The Well-Grounded Java Developer... • Is not just a Java language whizz – Understands the basics of the JVM – Understands software development is a social activity – Utilises software craftsmanship approaches – Understands architecture • Is looking at Java 7 • • Is looking at polyglot and functional programming • Is looking at modern concurrency practices 8Saturday, 24 December 11 8
  9. 9. Java 7 - Why is it important • The WGJD wants to code rapidly • The WGJD wants to code concisely • The WGJD wants to take advantage of: – The compiler (including JIT) – The JVM • Java 7 gives you many improvements in these areas 9Saturday, 24 December 11 9
  10. 10. OpenJDK - The Java 7/8 split • 20 Sep 2010 - Mark Reinhold announces Plan B – Splits OpenJDK effort into Java 7 (July 2011) and Java 8 (2013) – Popular choice with the community • July 2011 - Java 7 goes gold • Some new features to be delayed until JDK 8 – Closures Lambdas SAM literals – Modularisation (aka Jigsaw) • JRockit features to be merged into OpenJDK – Enhanced management of the JVM – Ongoing merge of the VM engineering groups 10Saturday, 24 December 11 10
  11. 11. Contents of JDK 7 Release • Project Coin • NIO.2 • Method Handles • invokedynamic • Concurrency Refresh • Odds & Ends 11Saturday, 24 December 11 11
  12. 12. Project Coin • “Small” changes • Language Level, not VM • Stay away from the type system • Developed in a very OSS manner – Was an ‘interesting’ experience for all involved 12Saturday, 24 December 11 12
  13. 13. Project Coin - Highlights • Strings in switch • try-with-resources (aka ARM or TWR) • Diamond Syntax • Multicatch with precise rethrow • Enhanced syntax for numeric literals • Varargs / autoboxing warning 13Saturday, 24 December 11 13
  14. 14. Strings in switch • Code along exercise: FeedingSchedule.java 14Saturday, 24 December 11 14
  15. 15. try-with-resources 15Saturday, 24 December 11 15
  16. 16. Diamond syntax • Code along exercise: HordeOfOtters.java 16Saturday, 24 December 11 16
  17. 17. Personally I’d stick to Java 1.4 17Saturday, 24 December 11 17
  18. 18. NIO.2 - New I/O version 2 • A new file system and path abstraction • Based on Path – An abstract view of a ‘file like’ system • Files class contains many helper methods, including – File manipulation (copy, move, rename etc) – Walking directory trees – Native file system support (e.g. symbolic links) • Works with existing java.io.File code 18Saturday, 24 December 11 18
  19. 19. NIO.2 - New I/O version 2 • Asynchronous (non-blocking) I/O • For sockets and files • Mainly utilises java.util.concurrent.Future • New NetworkChannel – Socket/Channel construct – Binding, options and multicast 19Saturday, 24 December 11 19
  20. 20. Path and Files - Some examples • Code along exercise: Housekeeping.java 20Saturday, 24 December 11 20
  21. 21. URL stream to file - Java 6 style NIO 21Saturday, 24 December 11 21
  22. 22. URL stream to file in Java 7 • Code along exercise: VetNotes.java 22Saturday, 24 December 11 22
  23. 23. NIO.2 - Future base file I/O 23Saturday, 24 December 11 23
  24. 24. Monty Python eat your heart out 24Saturday, 24 December 11 24
  25. 25. Method Handles • We already have Reflection API – It’s all pretty horrible • JDK 7 introduces a new way to inspect at runtime • Method Handles – Represent the ability to call a method – Implement a subclass of java.lang.invoke.MethodHandle – Are strongly-typed and typesafe – Needed for invokedynamic - but also used standalone 25Saturday, 24 December 11 25
  26. 26. Example - ThreadPoolManager 26Saturday, 24 December 11 26
  27. 27. Cancelling using Reflection 27Saturday, 24 December 11 27
  28. 28. Cancelling using MethodHandle 28Saturday, 24 December 11 28
  29. 29. invokedynamic • invokedynamic is a key new JVM feature – It’s the first new bytecode since Java 1.0 – Joins invokevirtual, invokestatic, invokeinterface and invokespecial • Relaxes a key part of the static typing system – User code can determine dispatch at runtime • Aims to be as fast as regular method dispatch – e.g. invokevirtual • No Java syntax in Java 7 – But maybe for Java 8 29Saturday, 24 December 11 29
  30. 30. invokedynamic contd. • JRuby, Jython, Groovy, Clojure et al all benefit – JRuby gains a lot, Clojure not so much – Even Scala is using it now! • JRuby has been working closely with the JSR-292 team – Big wins – Makes JRuby enticing to Ruby developers • Java 8 also gets a boost – Lambdas have a much nicer design with invokedynamic 30Saturday, 24 December 11 30
  31. 31. Other JVM Languages? Meh - Use the Golden Hammer! 31Saturday, 24 December 11 31
  32. 32. Java 7 Concurrency Refresh • Java 7 has a number of new concurrency toys • The headline item is Fork / Join – similar to MapReduce, useful for a certain class of problems – fork and join executions are not necessarily threads • We’ll cover this in the final hour! 32Saturday, 24 December 11 32
  33. 33. Java 7 - That’s not all • Nimbus Look & Feel for Swing • New helper classes including Objects – .deepEquals() and friends • Enhanced JDBC (including try-with-resources support) • Better unicode support – Thanks in part to Tom Christiansen of Perl fame • More small changes in niche areas 33Saturday, 24 December 11 33
  34. 34. New Faces in the OpenJDK 34 Original Image by AcabenSaturday, 24 December 11 34
  35. 35. What We Didn’t Have Time To Talk About • Java 8 – Java FX 2.0 • Java EE 6/7 • Java ME – Android and _that_ lawsuit • OpenJDK changes & JDK Enhancement Proposals (JEP) • Java Community Process (JCP) – Java Specification Requests (JSRs) – Java User Groups (JUGs) and reinvigorating the Community 35Saturday, 24 December 11 35
  36. 36. What? You still here? Go take a break will you! 36Saturday, 24 December 11 36

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