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The London Java Community’s next free event is – Java Native Interface with Eclipse and Android on Wednesday 12th June at 18:15 at Skills Matter, London.

Please see link for details and to sign up –

Presented by Jeff Lawson.

The Java Native Interface (JNI) enables Java developers to make use of C libraries for high-performance functions such as telephony, sound and graphics. JNI enables developers to re-use their existing C/C++-based software and opens up the opportunity to use the C/C++ libraries developed by the company or organisation they work for.

This event provides broad and detailed coverage of JNI across allplatforms and specifically for the Android NDK. This is a how-topresentation with fully working code samples and turn-key instructions for implementing all aspects of JNI listed below.

The presentation will be delivered using slides and live code demos.

The following subjects will be covered:

* What is JNI and why use it?
* Writing C functions and C++ methods callable from Java
* Mapping strings and other data types
* Writing callbacks into Java
* Exception handling
* Memory management
* Threading
* Using standard C libraries
* Using open source shared libraries, e.g. OpenJPEG
* Adding native code libraries to JAR files
* JNI with the Android NDK
* Targeting multiple processor architectures
* Using native APIs, e.g. OpenSL ES in Android 2.3
* Debugging native code in Eclipse

All slides and codes samples will be provided to attendees.

Who should attend:

Developers wishing to gain a good understanding of the Java NativeInterface plus the Android NDK.

This event assumes that attendees are Java developers with at least apassing acquaintance with C/C++. Attendees are assumed to have noexperience of JNI.


Jeff Lawson is a Java / C / C++ / Obj-C developer who works for an international telco. He wrote his first JNI-based product, a JNDI service provider, in 2001. He now uses JNI as a crucial and extensive part of his Android telephony development.

Please see link for details and to sign up –

Organised by RecWorks:


The London Java Community’s next free event is – Java Development Testing on Thursday 6th June at 18:15 at Skills Matter, London.

Please see link for details and to sign up –

A technical and interactive presentation on how ‘Development Testing’ is addressing the ever changing landscape of software delivery: high quality, secure applications, limited resources and an ever increasing pressure to launch faster across multiple channels!

Suited to a technical audience from developers, architects, testers to managers, this talk will be presented by Coverity, the global leaders in Development Testing.

Topics include:

Software complexity, static analysis, finding and fixing critical defects and security vulnerabilities, raising quality and accelerating time to market.  How this complementary methodology is supporting developers’ education to write better code and free up QA and SA teams to focus on functionality, UX and network security.  Automated unit testing – a powerful new slant on line coverage, and finally how all this can seamlessly integrate into your existing workflow, including Agile!


Ian Ashworth started his career as a civil and structural engineer but let his passion for software engineering preside. He followed a typical pathway as a developer, rising up the ranks to management and then later applying his expertise as a technical consultant within the financial services sector.  He brings years of experience working with various technologies and methodologies across a range of domains and now works with many well-known global brands helping them adopt Coverity’s Development Testing platform..

Please see link for details and to sign up –

Organised by RecWorks:




The London Java Community’s next free event is – The London Developer Sessions on Tuesday 21st May at 18:30.

Please see link for details and to sign up –

This is our monthly social gathering, which incorporates members of The London Java Community and Graduate Developer Communities. This is an informal social evening most of the evening will be spent having ad-hoc informal discussions in small groups.

We are back to The Slug and Lettuce this month: 19/20 Hanover Street, London We have had some fantastic feedback from those who have attended the event at this venue before and will be holding this month’s event in the same great location. The venue has a nicely sized function room with its own private bar, there are some great offers on beer, there is free wi-fi and it’s easy to move around and chat to lots of people. Most importantly it is a friendly and relaxed environment where developers can get together to chat and network.

The event will kick off at 6:30 PM and usually goes on until around 11:30 with members coming and going at all times throughout the evening. We usually attract 50 – 70 members so it is a lively event in which members, both junior and senior, can connect in a relaxed atmosphere and set the development world to rights.

Barry or another RecWorks team member will be onsite so if anyone is looking for free recruitment advice it’s a great chance to come along for a chat.

Please see link for details and to sign up –

Organised by RecWorks:





Just before Devoxx, the LJC held a Nashorn HackDay in conjunction with Oracle.

Nashorn, in case you’re new to it, is a brand-new implementation of Javascript which runs on top of the JVM.

There is already an existing JS-on-JVM implementation, called Rhino (after the animal on the cover of the O’Reilly Javascript book), which was developed by Mozilla. It is quite old, and was not architected in a way which makes it easy to update it to take advantage of modern JVM features. Having said that, Rhino (at least in its interpreted mode) is quite simple to understand, so if you’re interested in how an interpreter is implemented on top of the JVM – then you should look at the Rhino source code.

With Java 8, however, Nashorn (pronounced NAS-horn, not NASH-horn) replaces Rhino (Nashorn is actually the German word for Rhino) – and Rhino is being removed.

Nashorn is a from-scratch new JS implementation, and designed to take full advantage of all Java 7 & 8 features – including method handles and invokedynamic. It is the first JS implementation to pass the spec tests 100%.

It will ship with Java 8, but it is already & pretty good shape, and with the interest in it, we decided to take it for a spin before Devoxx…

The Hackday took place at Oracle’s Moorgate building – and we were very pleased to have Attila Szegedi, one of the Oracle engineers working on Nashorn as our guide.

Attila opened the day with a presentation about how to use the JS shell (jjs) & how to integrate running Java code from within JS (and how to use Java to call out & run JS scripts from within a Java program).

In the hack sessions, people focused on using Java libraries from Java, comparing JSON processing in JS vs in Java (& some rudimentary benchmarks) with more advanced users looking at trying to defeat the Nashorn security model & sandbox.

It seemed to go very smoothly, and if there’s interest, we’d definitely be keen to run more events focused on Nashorn over the Summer – let us know if this would be interesting (leave a comment below or email us).


What is the LJC

The London Java Community (LJC) is a group of Java Enthusiasts who are interested in benefiting from shared knowledge in the industry. Through our forum and regular meetings you can keep in touch with the latest industry developments, learn new Java (& other JVM) technologies, meet other developers, discuss technical/non technical issues and network further throughout the Java Community.