Java Language : New Features in a nutshell

Enabling the IBM Blue Stack with Java

October 18th 2010, Bangalore, India

© 2010 IBM CorporationConference materials may not be reproduced in whole or in

part without the prior written permission of IBM.

Java Language : New Features in a nutshell

Lakshmi Narasimhan


© 2010 IBM Corporation2 Bangalore, October 18th 2010

Agenda

Evolution of Java

Java eco-system

What’s driving the change

New Language Features in JDK7

Demo

Q&A

https://espresso.hursley.ibm.com/perl/secure/fetch/j9-60/Other/pxi32hs60/20090206_02/pxi32hs60-20090206_02-hsdk.jar



Disclaimer

Opinions/views expressed here are my own and should not be taken as IBM’s views.



Evolution of Java - Eras of Java Programming Language

1. Embedded System (1991-1994) Originally called Oak Aimed at electronic devices

2. Client Side System (1995-1997) Internet changed it all. Browsers and Applets gained popularity

3. Middle Tier System (1997-2007) Forms core of the 3-Tier Architecture Powers most of the Middleware systems.

4. Language for Languages (2007 onwards): Powering development of newer Programming Languages Clojure, Groovy, JRuby, Scala, Rhino, Jython…



Java eco-system

Relevance of “Java” brand name

– At least 15 known proprietary JVM implementations.

– >30 Free and open source implementations.

Image of Sun/Oracle in the Community

– More open participation through OpenJDK

– Multiple avenues available for contribution

Newer/simpler programming paradigms

– Combine the best of interpreted and compiled languages.

– Allow for rapid prototyping and development

MMP and Cloud scale architectures

– Thousands of “Clustered” JVMs



What’s driving the changes Faster

– Invoke Dynamic– Concurrency and Collections update

Smaller– Modular Java (Moved to Java8)

Easier– Coin– NIO2– Method to close a URLClassLoader

Nicer– Locale Enhancements– Unicode 6.0– Translucent shaped windows– Swing : Nimbus L&F, JLayer components– XRender pipeline for Java 2D



JDK7 Features - Faster

InvokeDynamic

Implemented via JSR-292

Improves compatibility between Java and various dynamic languages, such as Ruby and Python, by providing better-than-native implementations of these languages on top of the Java Runtime Environment (JRE).

Eliminates need for “Glue-code” in the program interpreters.

Addition of new bytecode – “invokedynamic”

Read More : http://java.sun.com/developer/technicalArticles/DynTypeLang/



JDK7 Features - Faster

Concurrency and collections update Implemented via JSR 166y

Light-weight task framework called ForkJoin(FJ)

Introduces Parallel-Array (PA) concept to Java (simlar to Map-Reduce?)

Recursive Parallel De-composition of tasks

Suited for MMP Architectures.

Read More : http://artisans-serverintellect-com.si-eioswww6.com/default.asp?W9



JDK7 Features - Easier

Project Coin: Small language changes

New IO2 to define a true filesystem API

Method to close a URLClassLoader



JDK7 Features – Easier

Project Coin Strings in switch: A simple change that improves regularity in the language

Improved Type Inference for Generic Instance Creation (diamond)




Project Coin Simplified varargs method invocation

– Type information from generics gets erased at compile-time.– Current implementation generates unchecked warning at call time.– Proposal moves warnings from call site to Method declaration.

An omnibus proposal for better integral literals



JDK7 Features – Easier

Project Coin

Automatic Resource Management : Automatically close the resources using a new try clause.

Applies to Streams, Reader/Writers, Channels, Sockets, SQL operations and even Graphics.

When the statement completes, whether normally or abruptly, all of its resources are closed automatically.

Obviates the need for manual resource termination which is error prone and ugly.

Exception chaining masks true failures needing more verbose code (OR) more debugging time.



Project Coin – Automatic Resource Management Lets accept it, even good programmers get it wrong!!

The same code with ARM would look like this:

Makes the code vastly clear and concise.

Downside is you lose WYSIWYG (a lot happens under the hood now)




New I/O 2 JSR203

Need

– Java I/O File API buggy and not fully fail-safe.

– Inconsistent behavior across platforms (eg: rename function)

– Limited support for operating on Files.

What NIO2 provides:

– “Path” Class Operations

– Support for Directory manipulation

– Recursive File operations – FileVisitor class

– Full support for Symbolic links

– WatchService API

Read more : http://java.sun.com/developer/technicalArticles/javase/nio/




Method to close a URLClassLoader Custom URLClassLoaders are commonly written for loading classes and resources

from file-system directories, jar files or URLs.

Current implementation does not guarantee a “refresh” of updated implementations loaded from a particular codebase.

A new method close() introduced in URLClassLoader which:

– Invalidates the loader (so new classes can be loaded)

– Closes any resource opened by it (jar files)



Method to close URLClassLoader

Code snippet

Foo.jar now gets updated somehow



Java7 Features - Nicer

Swing Enhancements

Swing JLayer component

– Universal decorator for Swing components.

– easily decorate your compound components and catch all Mouse, Keyboard and FocusEvent for all its subcomponents

– Greatly eliminates verbose AWTEventListeners

Nimbus L & F :

– Cross platform L&F based on Synth LAF.

– Implemented in Java6 update10.



Java7 Features - Nicer

XRender pipeline for Java 2D

a new Java2D graphics pipeline based upon the X11 XRender extension.

Aim is to leverage hardware acceleration for most of Java2D’s functionality.

Locale Enhancements

Support for IETF BCP 47 and UTR 35 (CLDR/LDML)

Unicode 6.0

Support for Unicode 6.0 (changed from original goal of 5.1)



Want to get your hands dirty?

Participate in the IBM SDK for Java7 Beta program

Visit https://www.ibm.com/developerworks/java/jdk/beta/index.html to enroll.



Questions?

https://espresso.hursley.ibm.com/perl/secure/fetch/j9-60/Other/pxi32hs60/20090206_02/pxi32hs60-20090206_02-hsdk.jar



Useful links

List of JVM implementations : http://en.wikipedia.org/wiki/List_of_Java_virtual_machines

Java7 features overview : http://tech.puredanger.com/java7/

Project coin updates : http://www.baptiste-wicht.com/2010/04/java-7-updates-project-coin/



JDK7 Features overview

Modularity A large-scale effort to refactor, or break up, the Java SE platform into smaller, separate,

interdependent modules.

Implemented via JSR-294

Java Programming language was not designed with Modularity in mind.

Many module systems currently exist:

– Most mature implementation is OSGi.

– IntelliJ, Eclipse and Netbeans offer their own Plugin architecture.

JSR 294 aims at making Modules natively supported by the language.

Smaller download, start-up performance, smaller footprint.

Has taken various Avatars : JSR 291 (Dynamic Component Support for Java SE), JSR 277 (Java Module System)



Modularity So what’s changing:

– ClassLoader Architecture

– New java.lang.Module package

– New “module” keyword

– New packaging & distribution formats (one package per module??)

“module” keyword can be used by compilers to generate “meta” information. These can then be used for runtime validation for module dependencies, versioning etc.

Implemented in OpenJDK via Project Jigsaw

Aimed at making not just Java Modularized but also application classes.

Jigsaw modules aimed to be compatible with OSGi systems.



JDK7 Features overview – Developer Productivity

Type Annotations

JSR308

Java6 Annotation syntax useful but limited.

Type Annotations allow more expressive programming

Example : List<@NonNull Object>

Tools (annotation processors) can then validate the code for errors.

Documents

Java Language : New Features in a nutshell