I want to create a mod for Minecraft, and I am aware it uses Java. I am currently learning JavaScript, and was wondering if I am able to use JavaScript for the SDK.
Yes and no.
Java is not Javascript...but a Java project can interpret Javascript
Java and Javascript are two completely different languages. However, there is a javascript interpreter created in Java, that you can plug in to java, called Rhino. However, although Rhino makes it easier to embed Javascript into your Java code, its not a simple drop in solution that would allow you to simply script what ever you want with out going through the effort of makin the proper connections. Definitely achievable, but you wont likely be able to start scripting without making that time investment to connect Java and Javascript.
Background story
The relationship between Javascript and Java is a rather shallow one. The similar name comes from a marketing plan back when it was being released by Netscape (which most developers ended up moving to the non-profit Mozilla). They made a deal with Sun (bought by Oracle) to share that similar name, but purely for marketing purposes.
Yes, it is possible to run JavaScript within a Java program, using the Rhino Javascript engine (for example).
However, this would not be a good way develop a Minecraft plugin / mod. None of your knowledge of the Javascript APIs would be relevant. Everything you did to interact with Minecraft would entail using Java classes and methods in the Java or Minecraft libraries.
My advice:
If your aim is to avoid learning Java ... don't be lazy. (You'll end up having to learn the Java APIs anyway. And learning another language will be good for you ... assuming you aspire to be a professional programmer.)
If your aim is to integrate some pre-existing Javascript code-base, it might work. But you might be better off porting the Javascript code to Java.
Sorry, Java and JavaScript are totally different languages. The "Java" in both of them was a marketing decision from ancient times.
They do share some of the same syntax that many languages share, however, so if you have learned JavaScript it might be a little easier to get started with Java. They are definitely NOT interchangeable, though.
Have a look at JDK1.6's ScriptEngine, the interface whose methods provide basic scripting functionality. Using these methods you can execute javascript. Numerous examples can be found on usage of this.
script support is avail from jdk 6 onwards:
reference link
However, this is not a full implementation of Rhino.
Related
As I've recently started using JRuby, more specifically building Java applications using Ruby code, I've started using Java Libraries such as LWJGL and Slick.
I know JRuby changes Java method names to a more ruby-esque structure, my question is, is there any current way to generate Ruby documentation, either from source or by conversion of current documentation or even based on what JRuby exposes the methods themselves as?
At some point when JRuby 1.6.7 is out I plan on cleaning this really rough project for just such a thing:
https://github.com/enebo/noridoc
The intention is it will weave both Java and Ruby syntax together and give reasonable documentation for a Rubyist wanting to know all Ruby methods. In it's current form you should be able to generate a reasonable set of HTML docs of Java code showing you all ruby aliased methods. You will need to screw around with the javadoc comment.
Oh and we plan on making this tool available out of the box in JRuby once it is good enough to merge.
What is the process involved with converting a Java web application to something like ASP.NET with Silverlight or alike?
I know many Java frameworks have been proted to .Net (either C# or VB.NET), but haven't really seen many web applications done. (I might be very wrong here)
I also know very little about Java programming but know C#, VB.NET and ASP.NET. I haven;t looked at silverlight yet but know what it can do to some extent. I do know though that Java syntax is very similar to that of C, C# and C++ as they all the the "{}" brackets and layed out similarly.
For arguments sake (just to get a handle and example) what would it take to convert something like Alfresco to a .NET type web app? Also, just want to add that I am not planning on doing it but want to know that if its even worth investing time in looking into Java applications to port to .NET.
Microsoft used to distribute a 'Java Language Conversion Wizard' to convert Java code into C# code, including substituting some of the common framework classes. It needs a lot of cleanup after the fact, but may be useful depending on what sort of code you're trying to convert. If you have access to the VS 2005 tools you should be able to install it.
Other than that, it's heavily dependent on how the code's structured. Finding a web framework that's similar to the Java framework used would probably be helpful. In many cases, I suspect it would be easier just to port the database and master page templates/stylesheets across and build the rest from scratch.
This page on MSDN might be useful: http://msdn.microsoft.com/en-us/gg715299.aspx.
It does a conceptual mapping of concepts in Java to concepts in .NET.
Regarding Giacomo's mention of the Java Language Conversion Assistant (JLCA), it is in fact retired and I wouldn't recommend relying too heavily on it. As he says there's quite a bit of cleanup to do but much of that depends on how you architected your app.
I just ordered an Android smartphone and want to start playing around with creating my own applications. Now the question is which language to use, the native Java or Python using SL4A (former ASE).
I tend to Python, as I know it much better than Java, but I'm wondering what I would be missing using a "second class" language on Android. On the SL4A website it is also stated to be alpha quality software, which is not exactly encouraging.
I'm also not quite sure what the limitations of the scripting environment are and if they would be problematic.
At the moment you cannot create a releasable program with Python (or any other scripting language) using SL4A. I have heard rumours that this is something Google is working on, but even if they do enable it Python apps are likely to be slow and power-hungry compared to Java. Also the scripting API only gives you access to a limited subset of the native Java API. I would not consider using SL4A for serious development work at the moment, only for one-off scripts and prototyping.
Take a look at Scala. It is a statically typed language on the JVM, but uses type inference to remove most of the noise that you get in Java. It also fully supports functional programming, and has a lot of pythonish features. Because it is statically typed it is as efficient as straight Java with none of the disadvantages. IMHO it is the language that Java should have been in the first place.
A lot of people are blogging about using Scala on Android, so Google around for more information.
More likely will depend what type of applications you will develop.
I would start with Java to become familiar with Android SDK. Anyway first you need to look into some examples, tutorials. Most of them are done in Java, and only a few, probably on the dev site of SL4A for that.
Also there is native development Android NDK, that can be programmed with C++.
But anyway Java rules for general applications.
Adding an update to Dave Kirby's answer:
Issue 55, Distribute scripts as APKs, in the issue tracker at SL4A deals specifically with that.
There is a solution being worked out (may be complete by now) described at SharingScripts. The only issue seems to be that you need to have a interpreter APK already installed.
you may want to check out Ruboto it is a framework for developing Android apps based on JRuby which means your JRuby code can call Android APIs and can also be called back from the Android Java side.
Here is an introduction article .
Consider ising Kivy, if you want to write Android apps with Python. The process of packing script to .apk file is described here.
The problem is, resulting .apk will be big (~7Mb for 300Kb data). It is obvious, because you need to pack there Python runtime and all libraries.
Another solution I have heard of, is Pygame for Android, but it works on lower lewel, so you need to draw graphics manually.
Unfortunately, I have not tried any of this ways yet, but it looks, that I'm going to start using kivy soon.
I've been reading about Rhino as a useful way to implement JavaScript inside my Java code.
After reading for a while, searching in google and here, I couldn't find a real reason for which I would use JavaScript inside Java.
Could you point some real world advantages you find on using Rhino for a regular Java application?
Note that since Java 6, the scripting API is in the standard Java library - see the documentation of the package javax.script. The API in javax.script is an adapted version of Rhino. The scripting API supports not only JavaScript, but many other scripting languages.
See Java Scripting Programmer's Guide
The front page there mentions some reasons you might want to use scripting:
Application extension/customization: You can "externalize" parts of your application - like configuration scripts, business logic/rules and math expressions for financial applications.
"Command line" shells for applications -for debugging, runtime/deploy time configuration etc. Most applications have a web-based GUI configuaration tool these days. But sysadmins/deployers frequently prefer command line tools. Instead of inventing ad-hoc scripting language for that purpose, a "standard" scripting language can be used.
An example: You can script Oracle Weblogic using Python scripts, for example to configure your application server domain, to start or stop the server and to do other administration tasks.
Processing XML with Rhino and E4X is a joy compared to most of the Java XML APIs
You have existing JavaScript that "just works" and you don't want to re-write it. This can happen if you have some calculation or processing happening on the client side and move it to the server.
All kinds of neat caching and code loading tricks.
Your problem is better solved by a more dynamic language then Java.
List comprehensions ;)
The benefit of embedding a script language like javascript into your software is that you can offer others a way to write plugins for your software without giving the source code away.
A reason to write the whole app in another language is that you are able to write an app for a company which deploys it in their Java EE environment without having to learn Java.
We use JS (via Rhino) for a DSL in one of our products. It isn't a great DSL, but that is a fault of how we use JS, rather than Rhino.
If you considering to .Net also, I suggests to get along with Rhino.
Besides Java enviroments, rhino is one of the best performance interpreter on .NET environment (using IKVM). On the other hands, nashorn is very slow on .net.
Porting your own Rhino project to .NET is not so difficult.
I am interested to create a drag-and-drop layout designer using only JavaScript, HTML and CSS. The designer will allow the user to drag the page elements from one place to another (something like Blogger's layout designer) to create a site layout. But I don't want to hand code everything in JavaScript, I would prefer to write my application in .NET (preferably) or Java and rely on a compiler to compile it to JavaScript and HTML.
What are the .NET or Java to JavaScript compilers that you have used and can recommend? For Java to JavaScript I know GWT is available. What about .NET to JavaScript? Microsoft did come out with Volta, but the project seems to be no longer available.
Look no further, you already mentioned GWT pick that!
It has a very good API and many good applications have use them.
Even JavaScript frameworks like http://extjs.com/ have GWT support.
I use it for an small JavaScript calendar recently.
To be honest, I don't really like JavaScript that much. Most of the times the errors are hard to track (specially for a non JavaScript guy as me) and the workarounds included some plug-ins for the explorer just to get exactly what a compiler should do. Catch silly error early.
In the other hand I'm very familiar with the Java Programming language, and many of the libraries (if not the most important) such as java.lang and java.util have been ported to GWT.
Plus, the guy who wrote relevant parts of java.util is the same behind GWT (google Joshua Bloch.)
Check out Nikhil Khotari's Script# project. It allows you to write C# code and compiles it to JavaScript.
Script# has already been mentioned. It hasn't been updated since August 2008.
Milescript is another, but also has seen very little for 6 months.
Extsharp for the Ext library. Adds Ext support for Script#
Javascript compiler to Java (going the wrong way for you)
Java to script Eclipse plugin
My issues with Script# (a known issue) is it doesn't support jQuery yet. However it comes with a very lightweight library to tie in with the .NET framework, in Nikhil's sscorlib.js file and ssfx.core.js files. And also has support for lots of other Javascript APIs (mostly Microsoft, seeing as he is in the ASP.NET team).
I'd love to see a Script# extension for jQuery (I'm thinking about writing it if it's easy enough). As it stands, most don't provide full compilation yet but they're certainly getting there.
Update: I wrote a small extension to enable JQuery support Script# a few months ago. The project can be found here.
I'm going to second the use of GWT. I've used it for several projects and, when used in combination with a modern editor like Eclipse or IDEA, it really makes the mess manageable.
It's important to note that not only does it allow you to write in Java and have that transformed into optimized and obfuscated Javascript it also comes with a substantial subset of the core Java API. In addition to this they provide lots of additional classes for doing things like parsing and working with JSON and XML and communicating with a server via asynchronous HTTP. You can check out the docs to get an idea of what else they offer.
Another feature that might be of special interest to you for implementing drag and drop functionality is it's integration with javascript libraries like Ext and scriptaculous. Either through pre-built interfaces or via JSNI
Also for Java there is J2S.
Java2Script (J2S) Pacemaker provides
an Eclipse Java to JavaScript compiler
plugin and an implementation of
JavaScript version of Eclipse Standard
Widget Toolkit (SWT) with other common
utilities, such as java.lang.* and
java.util.*. You can convert your
SWT-base Rich Client Platform (RCP)
into Rich Internet Application (RIA)
by Java2Script Pacemaker.
This means that if you use the SWT IDE (drag and drop) you can then convert the generated code to JS + HTML.
I wouldn't hand write any Javascript for UI. This can lead to maintenance disaster. jQuery is what I am using but I still wouldn't use it to write full UI Javascript code. ExtJS is also another good option if you plan to write in Javascript. In general what I am saying here is that it's so much easier to main in Java/C# than Javascript. Check out cappuccino framework and Atlas. Never used GWT. Script# is similar to GWT but for ASP.NET framework. Also depends on the requirement, if your site is public facing then RIA isn't a good option. It's all about which extreme end you pursuit (hand written and web standard, or RAD or libraries like jQuery/ExtJS as the middle option).
Check out Axial, a .NET to JavaScript converter that works well in ASP.NET. It supports WebForms, jQuery and canvas. It's not very mature, but it's worth a look.
http://jsc.sourceforge.net/ is a C# to JavaScript, Java, Flash and PHP compiler.
JscriptSuite offers another free .NET to Javascript compiler. There is a big difference to Saltarelle (jsc, SharpKit# etc.). Developer write down and debug only C# code (or any other .NET langauge), like in GWT. Javascript will be generated für deployment only.