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I'm working on getting an Introduction to Groovy presentation ready for my local Java User's Group and I've pretty much got it together. What I'd like to see is what you all think I just have to cover.
Remember, this is an introductory presentation. Most of the people are experienced Java developers, but I'm pretty sure they have little to no Groovy knowledge. I won't poison the well by mentioning what I've already got down to cover as I want to see what the community has to offer.
What are the best things I can cover (in a 1 hour time frame) that will help me effectively communicate to these Java developers how useful Groovy could be to them?
p.s. I'll share my presentation here later for anyone interested.
as promised now that my presentation has been presented here it is
I don't know anything about groovy so in a sense I've qualified to answer this...
I would want you to:
Tell me why I would want to use Scripting (in general) as opposed to Java-- what does it let me do quicker (as in development time), what does it make more readable. Give tantalising examples of ways I can use chunks of scripting in my mostly Java app. You want to make this relevant to Java devs moreso than tech-junkies.
With that out of the way, why Groovy? Why not Ruby, Python or whatever (which are all runnable on the JVM).
Don't show me syntax that Java can already do (if statements, loops etc) or if you do make it quick. It's as boring as hell to watch someone walk through language syntax 101 for 20min.
For syntax that has a comparible feature in Java maybe show them side by side quickly.
For syntax that is not in Java (closures etc) you can talk to them in a bit more detail.
Remember those examples from the first point. Show me one, fully working (or at least looking like it is).
At the end have question time. That is crazy important, and with that comes a burden on you to be a psuedo-guru :P.
I'm not sure about how the Java6 scripting support works but I'm fairly sure it can be made secure. I remember something about defining the API the script can use before it's run.
If this is the case then an example you could show would be some thick-client application (e.g. a music player) where users can write their own scripts with an API you provide them in Groovy which allows them to script their app in interesting and secure ways (e.g. creating custom columns in the playlist)
I'd go for:
Closures
Duck typing
Builders (XML builder and slurper)
GStrings
Grails
I'd mention the following things in addition to what has already been stated:
GDK - extensions/additions to existing JDK classes
Interaction between Groovy and Java code (basically a non-issue)
Compiling Groovy code to Java .class files
XML parsing and mechanisms for accessing document content
One thing I like doing with Groovy is implementing an interface defined in Java as a map from method names to closures. It's a cool thing you can do with Groovy, but probably well beyond an introductory presentation though.
Include an example of how making Java code more groovy takes away soooo much code. Wait for them to pick their jaws up off of the floor before continuing. Scott Davis has a simple example at the beginning of Groovy Recipes that takes 35 lines of Java or 3 lines of Groovy.
You should definitely show them how to create a quick Grails application. Two domain classes that are related. Build a basic CRUD app. Explain that tables are being created behind the scenes using GORM(Hibernate). Then explain that you can create a war file and deploy it as you would any other Java war file. You can also add Grails/Groovy to an existing Java/JSP project so it doesn't require a huge commitment or paradigm change.
Groovy/Grails is simply Ruby/Rails for Java people. I'd cover the plugins for Netbeans/Eclipse too. Groovy/Grails are just now getting full support in the major IDE's.
Finally, if you can find a good diagram that shows how Grails is built on top of Spring, Hibernate, Quartz, Sitemesh and Groovy, I think people will understand that there is a treasure chest waiting to be unlocked.
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And by the right guide, I mean one which doesn't necessarily focus entirely on how to program in Java, but puts forth a bit of effort on everything else. In other words, something which has enough information on the things which IDEs like Eclipse do for you, and how to manage those things without using an IDE.
Some examples of what I'm looking for:
How to import Java files without packaging them first.
How to specify directories for file/package imports, and where that specification needs
to be placed.
How to use Gedit to effectively program in Java with nothing but a few plugins and command line for compilation.
Great compiler error avoidance practices.
Seriously, I've looked enough now to come to the conclusion that Google really can't just hack what I need, and my best bet is an actual resource filled with lots of information.
If anyone has any ideas or thoughts on where I should look, or even an answer to any of these questions specifically, I would greatly appreciate the input.
IMHO you can't effectively program in Java without IDE (especially working on bigger project). You should learn about using/setting CLASSPATH, also check documentation for basic JDK commands (javac, java, jar, javadoc etc.).
Eclipse IDE has support for other important project tools e.g. Ant and Maven (for example with M2Eclipse plugin), so you can learn them too if you want.
Check this question for more lightweight IDE than Eclipse.
Java programming is quite a broad area. You may wish to do web-programming or Swing and there are lots of frameworks and framework combinations to work with.
If you want to be productive there is no way you can survive, especially for large projects, without using one IDE, or maybe even two. You will need a simple JUnit integration, as well as a debugger and automatic code generation for POJO methods, and autocompletion and refactoring capability and you name it.
I think that the best IDE for Swing development is Netbeans7. Matisse is implemented best, stable and fast. You can drag and drop anything you like anywhere and the generated code is always clear and well organized.
Eclipse has a great GWT-Designer. It is also great for Struts2 programming etc. Both work great with Maven and Ant and Hibernate.
If you need three months for a project you can do with an IDE in two weeks, there is no point in not using an IDE. On the other hand there are also masochists between us...
I recommend programming with an editor and the shell only for beginners, until they get the grasp of things and understand layouts, jars etc. Using a graphical tool to get started is wrong, since the students learn to drag and drop components mechanically and relying upon lack to get things straight. Only as soon as one knows how things work, is IDE a one way street. You never look back again. There is amazing free software today.
Eclipse has a very thorough Java dev guide, which should tell you pretty much everything it will do for you. http://archive.eclipse.org/eclipse/downloads/drops/R-3.1-200506271435/org.eclipse.jdt.doc.user.3.1.pdf.zip I think the guide does a decent job as far as helping you help yourself as well, so I think it could still be a worthy source for what you are seeeking.
In other words, something which has enough information on the things which IDEs like Eclipse do for you, and how to manage those things without using an IDE.
So you acknowledge IDEs are great. Why aren't you using one? In particular, IDEs come with step by step documentation on how to accomplish these simple tasks. I suspect the reason there is little IDE agnostic documentation on these things is that most people actually use IDEs.
Great compiler error avoidance practices.
I for one wouldn't want to code without the Quick Fix feature of eclipse ...
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I just got myself an android phone and I'm dying to start coding on it !
However I'm not a big java fan, although I can live with that, I would like to know if there're reasonable alternatives for the android virtual machine.
I've done a medium sized project using clojure, however from the reviews I read, it's very slow when running on android. How about scala ? I read that some people did experiments with it in android, is it "fast enough" ? How big is the learning curve ?
Cheers,
Ze Maria
There's the NDK which allows you to write parts of your program in C or C++.
There's ASE that allows you to write scripts in python and maybe other languages. There's no python compiler despite you might hear otherwise.
I have read something about scala but since I wasn't really interested I did not pay attention.
There's definitely quite a few people doing Android development in Scala. Of particular notice, there's even a plugin for SBT, the prefered builder for Scala projects, with Android-specific targets.
As for learning curve, I can't speak for Android development itself, as I haven't done that. As for Scala, you can be productive very quick, but learning all the particularities of the language takes time. You don't need to learn all the particularities -- I have seen people write non-toy programs with barely any experience -- but some people can't stand not knowing something about the language they are using.
Also, a lot of Scala code out there is very declarative. If you look at the SBT build files, for example, they are mostly declarative. Some people get very upset by that, for some reason.
I'm guessing what I'm trying to say is that it depends mostly on you how well you'll take to Scala.
As for speed, Scala code can be as fast as Java code, though that may call for avoiding the more high level abstractions in exchange for uglier, but fast, code. It depends a lot of what kind of computation you are doing, though.
Android 2.2 adds jit to the VM which is supposed to make loading Clojure programs much more efficient. Clojure produces a lot of small classes which take a while to load when the android program starts up. this should be alleviated with the enw android though its not intolerable now.
Just noticed that some Scala examples can be found in trunk: http://lampsvn.epfl.ch/trac/scala/browser/scala/trunk/docs/android-examples.
I haven't tried myself but it's encouraging.
There's a port of JRuby to Android, as well, which I've played with and seems interesting. http://ruboto.org/
"fast enough" - you are running applications on a mobile phone that question relative to what you expect it to do.
Also java's performance has been increased through the years. But also run you are just coding in java. Google has created a tool that take java byte code and converts it to .dex (Dalvik Executables). Dalvik the VM implementation that java used is optimized for this platform. Which mean you can program in a high level language like java which provides many helper classes which means you will be more productive.
They do have a NDK but I believe you have to still have a java front end and have your java code call the NDK code when necessary. You pretty much only want to write the native code when you really need to optimization. Alot of java classes like java nio and the opengl classes are just wrappers to low lever calls that use hardware resources directly.
I probably over answered you question a little.
There is also Lua, which you can use with the Corona SDK.
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I need to have an at-home project now that I'm working on Python/Django at work. I'd like to learn something new, so I was thinking of checking out Java.
What's the most well respected web framework for deploying Java web apps?
The only reason I'm not checking out ruby on rails is because of how similar the ORM and other parts are to Django.
Alternatively, does anyone think I should take a look at seaside/smalltalk? Can anyone explain why I should?
Haskell is something I'll consider if anyone can make a good argument for it. I'd need a web framework and database access library to go along with it though.
I'd consider factor/forth if I wasn't so accustomed to the stack paradigm via x86/asm. I'd be willing to hear any counter-arguments to this as well.
See also: http://www.reddit.com/r/programming/comments/9v3uf/asm_c_python_perl_lisp_scheme_programmer_looking/
With that range of skills, why don't you learn something more outside your comfort zone, like carpentry or painting, or any of hundreds of other skills that have little to do with your field.
At some point, all languages are the same and you'll get scant benefit from learning another.
Whereas, with something totally different, you will become a much more well-rounded individual. I, for one, like painting and golf, even though I'm not that good at either of them - when I asked my golf instructor what my handicap was, he said it was an inability to hit the ball straight :-)
I find that I enjoy doing stuff I'm not accustomed to since it's a genuinely new experience. Learning another computer skill is a easy thing to do after a while and hence the pleasure from doing it is reduced.
Don't get me wrong, I like to keep up with developments in the field but, for the most part, the brand new technologies give nothing to my career since most work I do is on stable technologies. You may be in a different situation.
Haskell is pretty popular these days as a mind-bender, though it may not hurt as much for you if you already know Lisp and Scheme. It's purely functional, so there are no side effects to anything. You have to use monads to print text and do other things that require a certain order. It's also completely lazily evaluated, so you can make infinite lists in Haskell and not have to worry about memory consumption.
The Haskell Platform may not be fully complete, but is intended to be a portable set of libraries for Haskell. It's list of packages includes some for CGI handling and (X)HTML generation.
Sounds like you're into web programming, so smalltalk/seaside is a great one. IMO everyone should learn smalltalk even if they never use it, and seaside is a really different web framework than what you are used to. Django, fer instance, is all about REST, while the seaside philosophy basically says "to hell with REST."
And if you've never coded in an image based environment there's just something about it that seems... natural, magical even. Lots of IDE functionality that originated in smalltalk have been implemented in file based language IDE's, but it always feels like an unnatural grafting, where those same features feel as if they simply belong there in smalltalk.
Check out Pharo. Give it enough time to get used to the fact that there's no menu bar and see if it doesn't grab you.
I do suggest Java. When I was looking for a job, I noticed lots of openings for Java developers, so there's a lot of it out there, and you might someday have a chance to use your Java skills.
And then you should try out Scala. Scala is a sort of Python-ish language that uses functional programming to make very scalable programs. Unlike Python, in Scala you do need to declare types of things. Scala runs on the Java Virtual Machine so it can be used in Java shops.
http://www.scala-lang.org/
It's possible I'm just giving you this answer because these are the next two languages I intend to learn, myself.
You probably should also spend a little time playing around with Javascript. Javascript was sort of intended to be a "stealth Lisp" and I imagine you would pick it right up.
http://www.crockford.com/javascript/javascript.html
http://bc.tech.coop/blog/030920.html
And heck, have some fun with it. Write a game or something!
From your list I'd say you are due for a completely object oriented language.
You could check out Ruby, but I'd recommend JavaScript since it offers a lot of interesting things you probably wouldn't expect, like support for closures, higher-order functions and prototypical inheritance - plus it's kinda fun and becoming very popular.
I'd need a web framework and database access library to go along with it though.
If all your programming is based on web frameworks and SQL databases, you will only be solving the same problems with different syntax if you switch languages.
Build something using a different data model - Prolog, Conceptual Graphs, RDF, Linda/JavaSpaces, XQuery, HDF5, ASN.1, or a different network model - XMPP pub-sub, SNMP, a zero-config mesh or a swarm of ZigBee enabled Arduinos.
Maybe look at languages like Oz, Io or Erlang/OTP, which are distributed rather than primarily monolithic like the ones you mention.
What about the Java Spring framework?
http://www.springsource.org/
Or maybe NHibernate?
http://en.wikipedia.org/wiki/NHibernate
At the end of the day its up to you. As I only listed two out of many. When I am programming a static language professonally... I try to learn a dynamic or scripting language. And vice versa.
Also, I try to learn something totally different or outside my realm... maybe even Powershell or Korn shell or ActionScript.
What's the most well respected web framework for deploying Java web apps?
There is no single web framework more respected than others. Struts2, Spring MVC, Stripes or Wicket (which is event based) are all good candidates (I personally like Stripes). But you'll need a bit more for the persistence (Hibernate or JPA) and for the glue (Spring).
Grails (Groovy on Rails) is another good option.
Alternatively, does anyone think I should take a look at seaside/smalltalk? Can anyone explain why I should?
Well, I guess that learning Smalltalk can't hurt but I don't see a good reason to choose Smalltalk over a moderner language like Java. Regarding tooling, I don't know anything in this field except VisualAge for Smalltalk but, personally, I'd really stay far away from it.
Haskell is something I'll consider if anyone can make a good argument for it. [...]
Looks like I'm not the right guy for that.
I'd consider factor/forth if I wasn't so accustomed to the stack paradigm via x86/asm. I'd be willing to hear any counter-arguments to this as well.
Same as above.
I would have suggested mastering Lisp (in some relevant dialect) so even if you have Lisp and Scheme on your resume, it might be worthwhile to REALLY learn deeply. See http://www.paulgraham.com/avg.html for reasons why.
Otherwise Prolog might interest you. It is related to SQL but for programming instead of communicating with an organised set of data tables.
If you want to target web technologies I only have experience with Java. Here the newest Java Server Faces (JSF) allow for using Ajax to update pages, and Google Web Toolkit allow for very rich component based web pages. These might be juicy enough to interest you enough to learn enough Java to find them fun :)
I don’t see C# and the .NET platform on your list. And I am surprised no one mentioned it yet.
I have worked in C# for 5 years. I have looked at some Java code but I have never coded in it. I believe that Java is somewhat similar to C# enough so that if you become proficient in one I think you could pick up the other is a matter of a few days.
One idea might be to create your own language / compiler. The one I would like to create (or see created) would be an Assembly Language level compiler with an object oriented syntax that would be very much like Python… but make it typed language. You could start with the basic raw binary types db, dw, dd, and then add on to these … The functions and methods could have assembly language freely mixed in the high-level code. Now, that would be a fun project, I think ?
Definitely try Haskell or Smalltalk or Forth.
I would say Smalltalk would be most useful while Forth would get you away from the x86 asm and C bullshit. There's more than one way to code close-to-the-hardware stuff.
Why don't you try OCaml? And if you ever happen (sadly) to return to .NET world - you will have knowledge of F# in your baggage.
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We're trying to determine how to implement a simple plugin framework for a service we are implementing that allows different types of calculators to be "plugged-in".
After reading a number of posts about Java plugin frameworks, it seems like the most common options are:
OSGI
"Rolling your own" plugin framework
The Java Plugin Framework (JPF)
The Java Simple Plugin Framework (JSPF)
OSGI seems to be more than we need.
"Rolling your own" is ok but it would be nice to reuse a common library.
So we're down to the JPF and JSPF. JPF doesn't seem to be in active development anymore.
JSPF seems very simple and really all we need. However I haven't heard much about it. I've only seen one post on StackOverflow about it. Does anyone else have any experience with JSPF? Or any other comments on this design choice?
Update: There isn't necessarily a correct answer to this.. however we're going to go with Pavol's idea as we need just a really, really simple solution. Thanks EoH for the nice guide.
(Disclaimer: I am the author of JSPF, so better take my comment with a grain of salt ;-)
The main reason I started with the JSPF was because I had the same problem as you have now: I was looking for a simple solution to make my thesis-project 1) extensible and 2) give it a more or less clear code structure.
The reason why I haven't decided to use an existing framework was because most of them were so heavyweight to start with, that I got lost in reading documentation and was almost forgetting my original task. So, according to your statement
We're trying to determine how to
implement a simple plugin framework
for a service we are implementing that
allows different types of calculators
to be "plugged-in".
I'd think that you could give JSPF a shot and see how far you come within one or two hours.
However, the final decision also depends a bit on what exactly you want to achieve, and the specific circumstances.
I have heard positive results from a number of individuals who have been using it to structure their projects or load plugins in their projects. On the other hand, I also know of one person in our department who discarded it again because he didn't feel it was mixing well with his programming style.
So, to answer your question briefly (and surely in a biased way), I would use
OSGi for projects and teams
which are large and have many people working on it
that justify the overhead of setting up the infrastructure
in need of the specific services offered
JPF for projects and teams
of medium size (?, honestly I am not sure about the project / team size they are targeting)
which are in need of more structured facilities to organize their code, like XML configurations, detailed plugin lifecycle management, extensible plugins ...
JSPF for projects and teams
of small size, following an agile paradigm
that just need something that works out of the box, without the need of configurations or setup
willing to sacrifice some features for simplicity
I hope you find the plugin framework most suitable for your scenario. And, no matter what you try, I would be happy to hear about your results.
If you are planning to have just one (or only a few) not very complex 'extension points' than perhaps a well-defined SPI and a piece of configuration might be sufficient. No need to use a plugin framework.
By piece of configuration I mean some mechanism to find your plugins. For example something like META-INF/services/ or simply listing your plugins in a configuration file.
More details (upon request):
SPI = Service Provider Interface, an "implementer-side equivalent of an API". To learn more try searching for a difference between API and SPI. However in this context it is just a fancy term for an interface to be implemented by your plugins (i.e. defines the contract for your plugins).
A nice, short article "Creating a Service Provider Interface" by Ethan Nicholas describes how to create your own SPI in similar way as it is done in several part of the Java Platform itself.
META-INF/services/ can be seen as a more generalized approach to creating SPIs. More information can be found in the respective section of the JAR File Specification.
If you need a really simple solution, try jin-plugin. It is a minimalistic plugin framework for Java and PHP.
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I was chatting to someone the other day who suggested that Rails and PHP are the most suitable platforms for web applications, and to avoid Java. My background is mainly Java, and I know that it is considered by some to be too verbose and "heavyweight", but is used occasionally (e.g. by LinkedIn).
So I'm wondering whether anyone has had success using Java for a recent web application that has gone live, either using the language itself (e.g. with Stripes/Spring + Hibernate), or the runtime with a dymamic language (such as JRuby, Groovy, Jython)? If so, please share what worked and what you would do differently.
Some background (added later):
Tim O'Reilly coined the phrased "Web 2.0" and here is his definition: http://www.oreillynet.com/lpt/a/6228
I think it's the "End of the release cycle" and "Lightweight programming model", involving rapid iterations and simplified deployment, where Java may be less suitable. Thoughts?
I would argue that there is no specific technology for Web 2.0. The main concept behind a Web 2.0 application is that much of the content is provided by it's users and not one specific person. If you can achieve this with Java, then that is fine. Many people are creating startup companies with technology that is free because they don't have the capital.
there are two totally different concepts called 'Web 2.0':
user generated content (usually with some 'social networking')
dynamic AJAX-based web apps
the second one somewhat dictates the technologies that you have to use (at least some JS, and machine-readable content in (some) responses). of course, there's nothing against using Java (or CGI, Perl, whatever) on the server.
the first one doesn't have anything to do with technology, and everything to do with the service itself you're providing. again, you can use anything you want.
why are these two mixed in the same therm? and more to your point: why are dynamic languages assumed 'more appropriate' for it? i'd guess it's just a temporal coincidence, all three things (user-generated content, AJAX, serious dynamic languages) jumped to the limelight roughly at the same time, and most of the proponents of each concept are using the other two.
in short, better avoid undefined marketroid terms like "web 2.0", and use proper descriptions. at least while working. when selling to the VCs and PHBs use any and all buzzwords that come near!
Of course it is. Java has some extremely mature and well tested frameworks for doing web applications, including so called Web 2.0 websites. Hibernate, Spring, even Struts and Tiles, or even Plain Old Servlets will do.
In addition, Java is very fast (see the Debian speed tests) compared to Ruby, which is good for websites handling lots and lots of requests, which Ajax does tend to inflate the number of! :)
Your friends, with all due respect, are dolts. Java is a rich language with incredible tools support. You could build a fantastic backend in Java and use anything you want for the front end.
It took me a while to figure out what to say in this answer because I was agape at the sheer craziness of the notion.
Where I work, all our applications are built using Java. They are web apps, built using either hibernate or direct JDBC on the data end, and using Struts or JSF for the presentation side. I would not work with JSF again unless we had access to the latest version (we were stuck on 1.0 because of our IDE) as we encountered MANY issues with it and were told that they had been fixed in later versions. As for the rest of the technologies, they work fine if you know how to use them.
In general, you are going to be better off developing in a language you know well and is capable of doing the job than in one you barely know but may be the "best" language for the job.
"Web 2.0" more often than not refers to the user interface than the underlying technology powering the webapp.
What's stopping a Java-based webapp from being totally flashy and AJAX-y in the UI layer? Nothing. You'll be writing the middle layers in Java - which is transparent to the user anyway.
I think that the people who gave you this advice are more concerned about being "hip" and (what they perceive to be) current with what is "hot" right now - which is totally irrelevant to the markup of your UI. I wouldn't listen to them.
Wonderful day, I get to post about Wicket again! :)
Java is very suitable for Web2.0 applications as long as you know how to use the tools which are available for you. The Apache Wicket I just linked is a POJO-based web application framework with such incredible way to hide all that boring server-client stuff that it allows you to do just about anything you can think of. The strong point here is that since Wicket is just POJOs, you can get very fast, iterative and unit tested code that works just as one would expect in browser.
To create Web2.0 sites with Java you don't of course have to use Wicket but I'd recommend it anyway.
I build Web apps at work in Java and then I use PHP for my personal projects. While Java is certainly capable of all that you might require it to do, I've found it a little cumbersome at times and have wished I was using PHP (or another language, for that matter). It does depend on what type and size of application you're building, but I think there are good reasons why many people choose PHP, Ruby and Python for their personal projects, i.e. where they get to choose what language they build Web apps in (and not their superiors).