crossedstreams.com

Quick Version

If, after ‘installing’ a plugin for Eclipse 3.4 it’s not visible in Preferences or in context menus, check that your user account has permissions to write into the appropriate Eclipse directories – because Eclipse doesn’t warn you.

Preamble

For those who don’t know, Eclipse is an IDE heavily used for Java development. Like anything else, it’s a delicate balance of awesome and suckage, and today I got caught out by a pinch of suckage.

It’s a plugin-based platform, which means that anyone can write a piece of software that ‘plugs-in’ to Eclipse to extend or enhance the functionality. It’s a great approach, allowing me to tailor my own installation to my needs. Having recently re-installed Ubuntu Linux, earlier today I was trying to set up my plugins without success.

The Problem

I set up the m2eclipse update site as described in the documentation (pretty standard fare… Help > Install New Software…, paste in the update site URL and choose components to install) but after ‘installation’ was completed there was no sign of the plugin. There should have been new options appearing all over Eclipse, but no. Tumbleweed.

Tried installing the next plugin on my list… Subclipse. Same story. So not a problem with a plugin…

The Solution

…and then it dawned on me. I’d installed Eclipse into /opt, which is all locked down to root, with administrative privileges. Schoolboy error – no permissions for the plugin files to actually be installed under the authority of my user account, which is the context that Eclipse normally runs.

A quick chown to root:admin for the /opt/eclipse directory (rather heavy handed – I should probably have worked out which directories I needed write access to, but I was out of patience), ‘uninstalled’ the plugin in the Eclipse, tried the install again and then I was back in business.

I’m really surprised that Eclipse doesn’t complain when it’s ‘installing’ a plugin in directories to which it has no access. I may not be the sharpest tool in the box, but I’m fairly sure that permissions problems happen to other people too. I might go so far as to find out where you feed back to the Eclipse development community for once. Anyways, this post will help remind me next time I get this wrong, it might help someone out, and if nothing else you might be mildly entertained by my ineptitude.

Paul Brabban Development, Java

Bit of a random one coming up…

I needed to get an measure of the difference in performance between Perl and Java for a simple client application, so I wrote the traditional ‘Hello World’ app in both and ran a bunch of executions averaging over the time from start to end of execution. The net result:

Perl is around 34 times faster than Java.

Really? I thought Java was supposed to be fast? In fact, Dhananjay Nene talked about how comparatively fast a selection of languages – including Java – were on his blog, and cwilbur ’s comments suggest that in that experiment:

Java is around 100 times faster than Perl.

So how can these two conflicting results both be true? I’m sure you’ve already figured it out, but I’m going to tell you anyway.

Java code takes hundreds of milliseconds to start up, because Java code runs in the Java Virtual Machine which needs a little time to get itself ready before your code can run. Once it’s up, however, you can get performance close to (or even better than, in reality) that of typical C++.

On the other hand, Perl doesn’t need that environment and so can start faster but trades off more overhead at runtime, meaning slower running performance.

Just goes to show, application performance is another area where there’s no one right answer – it’s about choosing the right tool for the job – I don’t think there’s any way round these performance characteristics without cheating.

Paul Brabban Development, Java, PERL

I was recently asked, why Java? It’s a great question – exactly why do I choose to learn the Java language?

I gave it some thought and I’ll share what I considered. I’m certainly not saying that what follows is a justification of the Java language in any general context, nor am I any kind of expert. This is just my view, given my circumstances.

It’s Free!

If you want to learn a language you don’t want to be laying out pots of cash up front. It’s likely you’ve got a Java Virtual Machine on your computer right now, and obtaining a development kit to get you started writing software is free and straightforward. Win.

The Java Virtual Machine

You never know when you might need to run that little app you wrote on a Windows host, or a different flavour of UNIX, or even a big ol’ IBM mainframe system – it’s nice to have some confidence that it’s just going to work.

Now, the JVM runs on any platform I can think of. Perhaps in the early days, there was some divergence in different platform implementations of Java (having felt the pain of the slight non-standard nature of the Micro$oft JVM in IE some time ago!) which somewhat hampered the cross-platform claim, these days there’s a suite of compliance tests that a JVM implementation must pass to brand itself Java compatible. That means that I don’t have to worry too much about cross-platform compatibility.

The JVM supports more than just the Java language. Jython, JRuby, Scala, JavaFX, Groovy, Fortress, Clojure… the list is getting ever longer, and there’s even a JVM Languages Summit. So, if you’re using the Java language and find a problem that better solved in another language, it’s perhaps not such a huge leap to get your Java code and your new JRuby code working together. Tim Bray wrote up some nice notes on the language summit here if you’re looking for a little more.

The other trick about the JVM is that your code gets better without you changing it. As new JVMs are released, they include the latest, hottest optimizations that take the software you write and give it go-faster stripes.

Tools and Platforms

Tool support for the Java language is extensive enough that there is generally a choice – for example, there is a choice of many Integrated Development Environments (Eclipse, NetBeans, IntelliJ IDEA to name but three) in which to write your software.

If you’re building ‘Enterprise’ software (whatever that really means!) you have a choice of application servers (WebSphere, JBoss, Jetty, Tomcat, GlassFish…) that all implement the Java Enterprise Edition specification in whole or in part (for example, the open source Tomcat application server supports a stripped-down subset of the spec) you know that any of the application servers should run your software.

With all these things the choices mean that I can choose the implementation with the right strengths and at the right price point for the project in hand.

Learning

Java’s got a lot going for it as a learning language – it seems to be on the syllabus for most computer science degrees. There’s a wealth of online material available for free, including Sun’s own learning trails and Sang Shin’s excellent javapassion.com learning site.

I know that the question of value in professional certification seems to polarize opinion, but there certainly is a certification trail in the Java language that’s not trivial to achieve.

The cost of achieving these certifications is financially quite insignificant, but (certainly for me – I’m sure there’s folks that find this stuff easier) demands a significant amount of time and commitment. The objectives and exam questions are put together by teams of Sun engineers, Java developers and Java instructors, orchestrated by Sun. (Thanks to Bert Bates and javaranch.com for that info!)

Having done a couple of certs myself, I found them to be a very useful useful guided tour of the language and its extensions. I found plenty of useful features and techniques whilst studying that have since steered me clear of errors and wasted time.

The JCP and Standards

New APIs for the Java language happen through the JCP, or Java Community Process. Everyone from from individuals to the largest IT players (IBM, Cisco Systems, Nokia – the members are listed here) are involved, and new standards happen in a publicly visible process of proposal and review.

Don’t believe me? Here’s the latest Java Enterprise Edition spec. See those JSR numbers? They’re the specifications that have been developed, reviewed and approved as part of the JCP.

Libraries

There’s sometimes so much choice of open source Java libraries, it’s hard to know what to choose for a given problem. The Apache Software Foundation hosts loads of open source Java projects, as does Google Code and java.net.

Not that every library is a piece of awesome… but many are. Having lots of choice increases the chances there’ll be something out there that’s already been built and tested and fits the bill. The libraries and APIs I have to use with my language of choice to get things done make a big impact to my productivity.

What – No Discussion of Technical Stuff?

Nope. I reckon it’s rather pointless to try and discuss differences between the capabilities of one language versus another. Anything computable can be computed in any Turing-complete language, which I think covers any language you might seriously approach as a general purpose problem solving platform.

So it’s not about what can or can’t be done – it’s really about what language I can be most effective and productive in. The biggest productivity killer in Java seems to be the boilerplate code necessary to do simple things, but over the last couple of years, strides forward have been made with annotations, for example, to reduce the boilerplate problem.

That’s All Folks

That’s about it, really. There’s plenty of other languages that can lay claim to some of the points I’ve made, but few that can claim them all.

There are other languages I choose for specific jobs (JavaScript for client-side behaviour in web browsers, PERL for sysadmin-type scripts) but my day to day workhorse, and the focus of my learning attention, is Java. For now, at least.

If I’ve missed anything or you disagree, feel free to drop me a comment!

Paul Brabban Development, Java