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Generate XML file from UML Model in Java

I want to make a java application that take UML Model and it's output is a XML File.
I want to know what is the library/API can i use in Java ? - and i want to know if there is any application that do this job ?

Most (if not all) UML tools will export to XMI, you can learn more at
Wikipedia MOF. If you are really interested in code generation (rather than just parsing XML) there are eclipse related projects such as eclipse emf. Good luck w/your journey.

Intellij parsing java code

I want to use a math-expression parser of java code. In particular I would like to convert a math-expression given as String to an abstract syntax tree consisted of separate nodes.
Is there anyone to recommend me a relevant open source tool?
If no, how do you reckon the possibility to exploit Intellij source code to do this work?
Which classes are responsible for code parsing and analysis?
Are they included in idea.jar? How can I easily infiltrate their functionality (methods etc)?
I am speaking exclusively for Intellij.

Take a look at MVEL library.

If you only want the results of the math-expression you should revise the question and the answer i selected months ago:
Java 1.5: mathematical formula parser
Brieff description: use the java integration with dinamyc languajes like javascript to let them do the work for you

I would not use IntelliJ, as much as I love it.
If you need an AST, look no further than ANTLR. If you can write a grammar for your equations, ANTLR can generate a lexer/parser to create it for you.

Is there any program like LINQPad for Java?

I've found LINQPad to be extremely useful when answering StackOverflow questions for C# or VB.NET. It allows me to write up some quick code, run it, and (if I want) see a nicely-formatted dump of the results. That way I can be sure that the code I post actually runs. Thus far I haven't seen anything that I can use to achieve the same result with Java. Is there anything like that out there?
I am not looking for something to query data sources; I just want a light-weight IDE. These are the features I'm particularly interested in:
The ability to write and run short snippets of code without establishing a whole project or file structure.
Reporting of compiler and runtime errors in the code when it is run.
The ability to add references to a particular editor instance.
Syntax highlighting and Autocomplete/Intellisense would be a plus.

JPad - A java scratchpad for running snippets
Since I also couldn't find one I've decided to write one. Currently it can:
Run java snippets (no class / imports / public blah... needed).
Contains drivers for MS/MySQL/Postgres.
Output results as HTML tables
It's very rough but I will add to it over time. Feedback is definitely welcome.

This may help : http://www.browxy.com:9000/codeRunner
EDIT: Url seems to have changed to http://www.browxy.com

You can use the Groovy web console ; it's possible to speak java in groovy land.

Java Snippet Runner:
Does something similar to Linqpad (jar file, not just for macs)
http://mac.softpedia.com/get/Development/Java/Java-Snippet-Runner.shtml
Code Runner (Commercial):
for Mac's only, it'll run code snippets in Java, and lots of other languages too (e.g. Objective C)
http://krillapps.com/coderunner/

http://ideone.com is an online service that has the features you want.

I've been using JEdit for a long time, which is a very powerful cross-platform editor, NOT an IDE. It does have plugins to execute Java code right in the editor, and even uses BSH for macros.

I was looking for a "Java LinqPad" also, and i came across :
this

I've been using IntelliJ IDEA and it works really well as a Groovy scratchpad. The Community Edition is free too.
You need to create a new project, but then can add Groovy scripts to it and run them on the fly. Not had any luck with the actual Scratch File functionality though.
Being a Jetbrains editor it's pretty slick too. (Unlike some of the other options)
Nothing beats LinqPad though.

Coding a parser for a domain specific language in Java

We want to design a simple domain specific language for writing test scripts to automatically test a XML-based interface of one of our applications. A sample test would be:
Get an input XML file from network shared folder or subversion repository
Import the XML file using the interface
Check if the import result message was successfull
Export the XML corresponding to the object that was just imported using the interface and check if it correct.
If the domain specific language can be declarative and its statements look as close as my sentences in the sample above as possible, it will be awesome because people won't necessarily have to be programmers to understand/write/maintain the tests. Something like:
newObject = GET FILE "http://svn/repos/template1.xml"
reponseMessage = IMPORT newObject
newObjectID = GET PROPERTY '/object/id/' FROM responseMessage
(..)
But then I'm not sure how to implement a simple parser for that languange in Java. Back in school, 10 years ago, I coded a language parser using Lex and Yacc for the C language. Maybe an approach would be to use some equivalent for Java?
Or, I could give up the idea of having a declarative language and choose an XML-based language instead, which would possibly be easier to create a parser for? What approach would you recommend?

You could try JavaCC or Antlr for creating a parser for your domain specific language. If the editors of that file are not programmers, I would prefer this approach over XML.

Take a look at Xtext - it will take a grammar definition and generate a parser as well as a fully-featured eclipse editor pluging with syntax highlighting and -checking.

ANTLR should suffice
ANTLR, ANother Tool for Language Recognition, is a language tool that provides a framework for constructing recognizers, interpreters, compilers, and translators from grammatical descriptions containing actions in a variety of target languages. ANTLR provides excellent support for tree construction, tree walking, translation, error recovery, and error reporting.

Look at Antlr library. You'll have to use EBNF grammatic to describe your language and then use Antlr to make java classes from your grammatic.

Have a look at how Cucumber defines its test cases:
(source: cukes.info)
http://cukes.info/ - can run in JRuby.

Or, I could give up the idea of having a declarative language and
choose an XML-based language instead,
which would possibly be easier to
create a parser for? What approach
would you recommend?
This could be easily done using XML to describe your test scenarios.
< GETFILE object="newObject" file="http://svn/repos/template1.xml"/ >
Since your example of syntax is quite simple, it should also be possible to simply use StringTokenizer to tokenize and parse these kind of scripts.
If you want to introduce more complex expressions or control structures you probably better choose ANTLR

I realize this thread is 3 years old but still feel prompted to offer my take on it. The questioner asked if Java could be used for a DSL to look as closely as possible like
Get an input XML file from network shared folder or subversion repository
Import the XML file using the interface
Check if the import result message was successfull
Export the XML corresponding to the object that was just imported
using the interface and check if it correct.
The answer is yes it can be done, and has been done for similar needs. Many years ago I built a Java DSL framework that - with simple customization - could allow the following syntax to be used for compilable, runnable code:
file InputFile
message Message
get InputFile from http://<....>
import Message from InputFile
if validate Message export Message
else
begin
! Signal an error
end
In the above, the keywords file, message, get, import, validate and export are all custom keywords, each one requiring two simple classes of less than a page of code to implement their compiler and runtime functions. As each piece of functionality is completed it is dropped into the framework, where it is immediately available to do its job.
Note that this is just one possible form; the exact syntax can be freely chosen by the implementor. The system is effectively a DIY high-level assembly language, using pre-written Java classes to perform all the functional blocks, both for compiling and for the runtime. The framework defines where these bits of functionality have to be placed, and provides the necessary abstract classes and interfaces to be implemented.
The system meets the primary need of clarity, where non-programmers can easily see what's happening. Changes can be made quickly and run immediately as compilation is almost instantaneous.
Complete (open) source code is available on request. There's a generic Java version and also one for Android.

Is there something like JET (Java Emitter Templates) but without Eclipse-dependencies?

I wanted to use JET (Java Emitter Templates)
in my Netbeans projects, but had to find out that JET
heavily depends on Eclipse libraries.
Is there something similar to JET, but as a standalone project?
Something which is open source and well maintained?
Futhermore, is "code generation" the common term for such tools?

If you are using Maven, you can use JET templates with the maven-jet-plugin.
This seems to be the source code. And here the documentation.
It is not actively maintained but works pretty well and follows the JET spec.
I've used it with templates and skeletons.
It's self contained, doesn't depend on Eclipse, and doesn't introduce any transitive dependencies to your project.

Indeed JET is very tied with Eclipse.
If you want to generate code without Eclipse you should use another solution.
You can choose another template engine like Velocity (https://velocity.apache.org/) or FreeMarker (https://freemarker.apache.org/).
Or you can choose a code generator working by itself independently of any IDE.
For example "Telosys Command Line Interface" : http://www.telosys.org/

From what I know, JET is something like JSP, no?
Java Emitter Templates are very similar to Java Server Pages (JSPs). Both JETs and JSPs use the same syntax, and are compiled to Java behind the scenes. Both are used to separate the responsibility for rendering pages from the model and controller. Both accept objects passed into them as an input argument, both allow inserting string values within code ("expressions"), and allow direct use of Java code to perform loops, declare variable, or perform logical flows ("scriptlets"). Both are good ways of representing the structure of a generated object (web page, Java class, or file) while supporting customization of the details.
JETs differ from JSPs in a few key ways. In a JET, the structure of the markup may be changed to support generating code in different languages. Typically the input to a JET will be a configuration file and not user input (though there is nothing forbidding this). And also typically, JET processing will take place only once for a given workflow. These are not technical limitations, and you may find uses for JETs which are quite different...
ibm.com
Here are a few links to get you started on JSP, if that sounds like what you need:
sun.com
netbeans.org

Look for "template engine" for these types of tools.
A couple you might want to look at:
Apache Velocity (http://velocity.apache.org/)
StringTemplate (http://stringtemplate.org/)

I ended up using ERB (Ruby's template engine).
Works great in Netbeans!
I define custom ant task which generates source files by calling ERB (whose results are placed inside a non-versioned special directory).
The ant task is overriding Netbeans' "-pre-compile" task.