This document provides an agenda and introduction for a presentation on Java 7 given by Ben Evans and Martijn Verburg. The presentation will cover introductions to Java 7 features like Project Coin, NIO.2, Method Handles, invokedynamic, and concurrency updates. It will also briefly discuss polyglot and functional programming and modern Java concurrency practices. The agenda outlines the scheduled topics and time allotted for each section and breaks.

1. The WGJD - Intro to Java 7
Ben Evans and Martijn Verburg
(@kittylyst @karianna)
http://www.teamsparq.net
Slide Design by http://www.kerrykenneally.com
Saturday, 24 December 11 1

2. This is not an Oracle legal slide
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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
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4. Who are these two anyway?
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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
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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
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7. Real Developers code through
bathroom breaks
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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
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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
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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
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11. Contents of JDK 7 Release
• Project Coin
• NIO.2
• Method Handles
• invokedynamic
• Concurrency Refresh
• Odds & Ends
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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
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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
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14. Strings in switch
• Code along exercise: FeedingSchedule.java
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15. try-with-resources
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16. Diamond syntax
• Code along exercise: HordeOfOtters.java
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17. Personally I’d stick to Java 1.4
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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
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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
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20. Path and Files - Some examples
• Code along exercise: Housekeeping.java
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21. URL stream to file - Java 6 style NIO
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22. URL stream to file in Java 7
• Code along exercise: VetNotes.java
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23. NIO.2 - Future base file I/O
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24. Monty Python eat your heart out
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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
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26. Example - ThreadPoolManager
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27. Cancelling using Reflection
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28. Cancelling using MethodHandle
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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
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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
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31. Other JVM Languages?
Meh - Use the Golden Hammer!
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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!
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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
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34. New Faces in the OpenJDK
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Original Image by Acaben
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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
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36. What? You still here?
Go take a break will you!
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