The evolution history of Java. What Java is good for? The rising of dynamic languages in JVM.

1. The Evolution of Java
Fu Cheng

2. Author of Understanding the Java 7 Author of 40+ technical articles on

3. We talk about ...

4. Java is …
A Programming Language
Just like C/C++, Ruby, Python and many others

5. Java is ...
A Programming Platform
Language + Libraries + VM

6. Java is ...
Popular

7. Java is ...
http://en.wikipedia.org/wiki/History_of_programming_languages
Old - maybe not old enough

8. Java is ...
Object-Oriented
Nearly everything is a object

9. Java is ...
Easy to learn

10. Java is ...
(Maybe) too easy to learn
The Perils of JavaSchools
by Joel Spolsky
Java is not, generally, a hard enough
programming language that it can be
used to discriminate between great
programmers and mediocre programmers.

11. Java is …
JDK 1.0
1996 1997 1998 2004 20062000 2002 2011
JDK 1.1
J2SE 1.2
J2SE 1.3
J2SE 1.4
J2SE 5.0
Java SE 6
Java SE 7
http://en.wikipedia.org/wiki/Java_(programming_language)#Versions
Slowly evolving

12. Java has ...
Strong Platform Medium language
Weak core libraries

13. Popular Platform
• Desktop
– 850M PCs, 2011
• Mobile
– Android
– Java ME
• Enterprise
– LinkedIn
– Ebay
– Paypal
– AOL
– Alibaba
– Netflix
http://w3techs.com/technologies/details/pl-java/all/all

14. JVM
• Shield applications from OS layer details
– Threading using java.lang.Thread
• Provide runtime support for applications
– Basic types and operators
– Object model
– Unicode support
– Dynamic linkage
– Garbage collection
– Memory model
– Access control

15. Java Language
• Static typed
• Strict & rigid syntax
It's hard to say language X is better than language Y.
Use the right tool.

16. Java is good for ...
Big Teams Long-term projects
The key is maintainability.
Code readability
Find good developers
High-profile projects

17. Core Libraries
• Java core libraries are weak
– Collections
– IO
– Date/Time
• Rely on communities
– Apache Commons XXX
• Problems
– Version conflicts
– Jar hell
– Dependency management

18. http://www.slideshare.net/vishnu/the-top-10-reasons-the-ruby-programming-language-sucks
The Top 10 Reasons The Ruby Programming Language Sucks
-Matz
See Ruby

19. Why Java Succeeded

20. Compile Once, Run Anywhere
Java Source Code
(.java)
Java Byte Code
(.class)Compile
Java Compiler
JVM
Win *Nix Mac
Java Language
Specification
JVM
Specification
Run

21. Class loader
• Java's true invention
• Load code from remote
and execute locally
• Core technique behind
Java Applet
• Java applet boosted
Java’s spreading in dot
com age
NASA World Wind applet

22. How Java Evolves

23. Java Community Process
OpenJDK
+

24. Java Community Process
Develop standard technical specifications for Java
technology
Java Specification Request (JSR) - Changes to make
http://jcp.org/en/procedures/overview

25. Member
Executive Committee
(EC)
- Individuals
- Companies
- Organizations
- Major stakeholders
- Representative cross-section of
the Java Community
JSRs
Game of big players
Eclipse Foundation
HP
IBM
Intel
Nokia
Oracle
Red Hat
SAP
Twitter
and more ...
submit approve

26. OpenJDK
• Open-source implemenation of Java SE
• Reference implementation of JCP JSRs
• Base of other Java SE implementations
• Oracle collaboration with Red Hat, IBM, Apple, and
SAP

27. What Happened Behind Java SE 7 JSR
JSR 336 JavaTMSE7ReleaseContents
Final Approval Ballot
http://jcp.org/en/jsr/results?id=5225

28. Those Voted 'Yes' Said ...
http://jcp.org/en/jsr/results?id=5225

29. Licensing Terms of TCK
• Technology Compatibility Kit (TCK) is used to test
compatibility of Java implementation.
• Oracle only wants to license the use of TCK in the OpenJDK
context
• Apache Software Foundation, Doug Lea and Tim Peierls
resigned from JCP EC in protest over this issue.
– Apache Harmony Project - retried already
Oracle ... has essentially turned the JCP
into a rubber-stamp organization for Java SE 7
Alex Handy

30. Evolution Areas of Java
Productivity Performance Modularization

31. Productivity

32. Averaging over the lifetime of the project, a programmer
spends about 10-20% of his time writing code, and most
programmers write about 10-12 lines of code per day that
goes into the final product, regardless of their skill level.
http://automagical.rationalmind.net/2010/08/17/some-lesser-known-truths-about-programming/

33. http://www.codinghorror.com/blog/2005/08/are-all-programming-languages-the-same.html
Lines of Code

34. Java is improving
• Java SE 5
– Enhanced for loop
• Java SE 7
– try-with-resources
– Diamond operator
• Java SE 8
– List & Map literals
– Lambda expressions
Example of lambda expression
http://docs.oracle.com/javase/tutorial/java/javaOO/lambdaexpressions.html

35. Performance

36. Java is NOT slow

37. Benchmark Result 1
http://blog.cfelde.com/2010/06/c-vs-java-performance/

38. Benchmark Result 2
http://readwrite.com/2011/06/06/cpp-go-java-scala-performance-benchmark

39. Most of the performance issues are caused by
programming errors
•Bad algorithms
•Careless memory usage
•I/O operations
•Threading issues, dead lock

40. Java is improving
• Performance was not good prior to Java 1.3
• Performance improved since HotSpot was
introduced in Java 1.3
• Each Java release has performance
improvements
JVM in OpenJDK = HotSpot + JRockit

41. Modularization

42. Why you need Swing library for an application server?
Project Jigsaw
Design and implement a
standard module system for the
Java SE platform, and to apply
that system to the platform itself
and to the JDK
http://openjdk.java.net/projects/jigsaw/

43. JVM Languages

44. Rise of Dynamic JVM Languages
And more ...
https://en.wikipedia.org/wiki/List_of_JVM_languages

45. Source code Java byte code
JVM
Compile
Run
Jython
JRuby
Groovy
Scala
Clojure
...

46. the Da Vinci Machine Project
Extend the JVM with first-
class architectural
support for languages
other than Java,
especially dynamic
languages.
http://openjdk.java.net/projects/mlvm/

47. Meet 'invokedynamic'
• A new JVM instruction introduced in JSR 292
for Java SE 7
• Allow extremely fast dynamic invocation
through method handles
• Improve performance of dynamic JVM
languages
http://jcp.org/en/jsr/detail?id=292

48. Polyglot and poly-paradigm
programming
Use the right language to solve problems in different
components
http://polyglotprogramming.com/papers/PolyglotPolyParadigm.pdf
Core business logic
Admin tasks
Web development
Concurrent programming

49. What should Java developers do?

50. Learn more about Java platform
Learn more JVM internals, class loading, byte code spec, etc.

51. Keep an eye on Java language
Use new features and enhancements to increase productivity

52. Embrace dynamic JVM languages
Learn new dynamic JVM languages to make your life easier

53. Java may not be a good programming language
Java platform is a good platform to work on
It’s evolving slowly
AND
BUT