The Evolution of Java

Fu Cheng

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

We talk about ...

Java is …

A Programming Language

Just like C/C++, Ruby, Python and many others

Java is ...

A Programming Platform

Language + Libraries + VM

Java is ...Popular

Java is ...

http://en.wikipedia.org/wiki/History_of_programming_languages

Old - maybe not old enough

Java is ...

Object-Oriented

Nearly everything is a object

Java is ...Easy to learn

Java is ...(Maybe) too easy to learn

The Perils of JavaSchoolsby Joel Spolsky

Java is not, generally, a hard enoughprogramming language that it can be used to discriminate between great

programmers and mediocre programmers.

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

Java has ...

Strong Platform Medium language

Weak core libraries

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

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

Java Language

• Static typed• Strict & rigid syntax

It's hard to say language X is better than language Y.

Use the right tool.

Java is good for ...

Big Teams Long-term projects

The key is maintainability.Code readabilityFind good developers

High-profile projects

Core Libraries

• Java core libraries are weak– Collections– IO– Date/Time

• Rely on communities– Apache Commons XXX

• Problems– Version conflicts– Jar hell– Dependency management

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

Why Java Succeeded

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

Class loader

• Java's true invention• Load code from remote

and execute locally• Core technique behind J

ava Applet• Java applet boosted Jav

a’s spreading in dot com age

NASA World Wind applet

How Java Evolves

Java Community Process

OpenJDK

+

Java Community Process

Develop standard technical specifications for Java technology

Java Specification Request (JSR) - Changes to make

http://jcp.org/en/procedures/overview

MemberExecutive Committee

(EC)

- Individuals- Companies- Organizations

- Major stakeholders- Representative cross-section of the Java Community

JSRs

Game of big players

Eclipse FoundationHPIBMIntelNokiaOracleRed HatSAPTwitterand more ...

submit approve

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 S

AP

What Happened Behind Java SE 7 JSR

JSR 336 JavaTM SE 7 Release Contents

Final Approval Ballot

http://jcp.org/en/jsr/results?id=5225

Those Voted 'Yes' Said ...

http://jcp.org/en/jsr/results?id=5225

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

Evolution Areas of Java

Productivity Performance Modularization

Productivity

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/

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

Lines of Code

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

Performance

Java is NOT slow

Benchmark Result 1

http://blog.cfelde.com/2010/06/c-vs-java-performance/

Benchmark Result 2

http://readwrite.com/2011/06/06/cpp-go-java-scala-performance-benchmark

Most of the performance issues are caused by programming errors

•Bad algorithms•Careless memory usage•I/O operations•Threading issues, dead lock

Java is improving

• Performance was not good prior to Java 1.3• Performance improved since HotSpot was intr

oduced in Java 1.3• Each Java release has performance improvem

ents

JVM in OpenJDK = HotSpot + JRockit

Modularization

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/

JVM Languages

Rise of Dynamic JVM Languages

And more ... https://en.wikipedia.org/wiki/List_of_JVM_languages

Source code Java byte code

JVM

CompileRun

JythonJRubyGroovyScalaClojure...

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/

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

Polyglot and poly-paradigm programming

Use the right language to solve problems in different components

http://polyglotprogramming.com/papers/PolyglotPolyParadigm.pdf

Core business logicAdmin tasks

Web development

Concurrent programming

What should Java developers do?

Learn more about Java platform

Learn more JVM internals, class loading, byte code spec, etc.

Keep an eye on Java language

Use new features and enhancements to increase productivity

Embrace dynamic JVM languages

Learn new dynamic JVM languages to make your life easier

Java may not be a good programming language

Java platform is a good platform to work on

It’s evolving slowly

AND

BUT