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[Xtend] Lists in JAVA extensions [message #536729]

Sun, 30 May 2010 13:31

Hauke Fuhrmann

Messages: 333
Registered: July 2009

Senior Member

Hi there,

for a Java internal calculation, I need to either
* pass a List as parameter to a JAVA extension or
* get a List as return value from a JAVA extension

How do I do those?

The Xtend reference does not say anything about return values of Java
extension methods at all. So how are they handled?

When I try one of these, I always get
"[Callable not found] - getPorts : getPorts"

--- xtend file
Void getPorts(List ports) :
JAVA my.PtolemyHelper.getPorts(java.util.List);

--- java file
public static void getPorts(java.util.List ports){
System.out.println("test");
}

It's the same when I change java.util.List with
org.eclipse.emf.common.util.EList.

So how can I pass an Xtend List to Java? And how could I return a Java
list to Xtend?

Cheers,
Hauke

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Re: [Xtend] Lists in JAVA extensions [message #536732 is a reply to message #536729]

Sun, 30 May 2010 14:40

Christian Dietrich

Messages: 14665
Registered: July 2009

Senior Member

Hello Hauke,

the extension / java class you defined looks ok and work in my hello world example.

The exception you get hints to some configuration / metamodel / classpath problem so please veryfy that the configuration is correct and that everything can be found on the classpath.

Regards, Christian

Twitter : @chrdietrich
Blog : https://www.dietrich-it.de

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Re: [Xtend] Lists in JAVA extensions [message #536733 is a reply to message #536729]

Sun, 30 May 2010 14:52

Gerd Kainz

Messages: 23
Registered: May 2010

Junior Member

Hi Hauke,

this might solve your problem.

Xtend:

List[Node] getPassedNodes(List[Node] nodes): JAVA javacode.Routing.getPassedNodes(java.util.List);

Java:

package javacode;

import org.eclipse.emf.common.util.BasicEList;

public class Routing {
	public static List<Node> getPassedNodes(List<Node> nodes) {
		List<Node> passedNodes;

		passedNodes = new BasicEList<Node>();
		passedNodes.addAll(nodes);

		return passedNodes;
	}
}

It's important that you specify the return type of your Xtend function even if you don't need to specify it for your Java method in Xtend.

As Alternative to BasicEList you can use any List implementation such as ArrayList.

Best regards,
Gerd

[Updated on: Sun, 30 May 2010 14:53]

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Re: [Xtend] Lists in JAVA extensions [message #536752 is a reply to message #536733]

Sun, 30 May 2010 17:09

Sven Efftinge

Messages: 1823
Registered: July 2009

Senior Member

Hi Gerd,

Gerd Kainz schrieb:
> It's important that you specify the return type of your Xtend function
> even if you don't need to specify it for your Java method in Xtend.

In the case of Java extensions specifying return types is mandatory.
But Hauke used void/Void as the return type which is perfectly ok.

So I don't think that your suggestion solves the issue.

Sven

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Re: [Xtend] Lists in JAVA extensions [message #536753 is a reply to message #536729]

Sun, 30 May 2010 17:10

Sven Efftinge

Messages: 1823
Registered: July 2009

Senior Member

Hauke,

how and from where do you call the extension?

Sven

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Re: [Xtend] Lists in JAVA extensions [message #536771 is a reply to message #536753]

Sun, 30 May 2010 19:15

Hauke Fuhrmann

Messages: 333
Registered: July 2009

Senior Member

Sven Efftinge schrieb:
> how and from where do you call the extension?

Hmm... not sure I understand the question. I would say "the normal way"...

I use the extension as a model-to-model transformation from a Workflow
that I instanciated programmatically in Java code. I execute the
transformation by an Eclipse UI command handler.

The Xtend file is correctly found and all the rest of the transformation
is running. The static Java method is in a Java class in the same plugin
as the Xtend file and the command handler. A simple "test(String)" Java
extension in the same file works without problems. Hence it must be a
problem with the parameters somehow.

Cheers,
Hauke

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Re: [Xtend] Lists in JAVA extensions [message #536780 is a reply to message #536771]

Sun, 30 May 2010 21:36

Sven Efftinge

Messages: 1823
Registered: July 2009

Senior Member

I just tested it in a normal java process using the example the wizard
generates.
I was able to define the following two methods

List[Entity] entities(Model this) :
JAVA metamodel.Helper.getEntities(org.eclipse.emf.ecore.EObject);

Model model(List[Entity] this) :
JAVA metamodel.Helper.getModel(org.eclipse.emf.common.util.EList) ;

which were bound to the following two Java signatures:

public static EList<EObject> getEntities(EObject obj)
public static EObject getModel(EList<EObject> list)

No problem.
It seems that it has something to do with the OSGi context.

Sven

Hauke Fuhrmann schrieb:
> Sven Efftinge schrieb:
>> how and from where do you call the extension?
>
> Hmm... not sure I understand the question. I would say "the normal way"...
>
> I use the extension as a model-to-model transformation from a Workflow
> that I instanciated programmatically in Java code. I execute the
> transformation by an Eclipse UI command handler.
>
> The Xtend file is correctly found and all the rest of the transformation
> is running. The static Java method is in a Java class in the same plugin
> as the Xtend file and the command handler. A simple "test(String)" Java
> extension in the same file works without problems. Hence it must be a
> problem with the parameters somehow.
>
> Cheers,
> Hauke

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Re: [Xtend] Lists in JAVA extensions [message #536781 is a reply to message #536771]

Sun, 30 May 2010 21:47

Hauke Fuhrmann

Messages: 333
Registered: July 2009

Senior Member

It looks like it's at all no problem with passing lists, but with
another parameter (first I tried to reduce the example to a smaller
case, which seems to actually not show the problem):

--- xtend
Void test(EntityType entity) :
JAVA my.Test.test(my.metamodel.EntityType)
;
--- java
public static void test(EntityType test) {
System.out.println(test.getName());
}

Then I get the [Callable not found] error.
The generated my.metamodel code is in the same plugin. Is there a
problem with passing such custom metamodel objects?

A strange workaround is to wrap the EntityType parameter in a List. That
works.

Hauke

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Re: [Xtend] Lists in JAVA extensions [message #536807 is a reply to message #536781]

Mon, 31 May 2010 06:18

Sven Efftinge

Messages: 1823
Registered: July 2009

Senior Member

Hauke Fuhrmann schrieb:
> It looks like it's at all no problem with passing lists, but with
> another parameter (first I tried to reduce the example to a smaller
> case, which seems to actually not show the problem):
>
> --- xtend
> Void test(EntityType entity) :
> JAVA my.Test.test(my.metamodel.EntityType)
> ;
> --- java
> public static void test(EntityType test) {
> System.out.println(test.getName());
> }
>
> Then I get the [Callable not found] error.
> The generated my.metamodel code is in the same plugin. Is there a
> problem with passing such custom metamodel objects?

What makes this type 'custom' (i.e. special)?
What kind of meta model do you use? I suspect that you face the problem
when running the generator. If that is the case, please share the
configuration of your workflow, especially the metaModel part.

Sven

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Re: [Xtend] Lists in JAVA extensions [message #536931 is a reply to message #536807]

Mon, 31 May 2010 14:30

Hauke Fuhrmann

Messages: 333
Registered: July 2009

Senior Member

Sven Efftinge schrieb:
> What makes this type 'custom' (i.e. special)?

Well, its some instance object of my metamodel. So it's not really
special. But it's not a primitive.

> What kind of meta model do you use? I suspect that you face the problem
> when running the generator. If that is the case, please share the
> configuration of your workflow, especially the metaModel part.

I call it from a Java plugin in a command handler. If you want to see it:

http://rtsys.informatik.uni-kiel.de/trac/kieler/browser/trun k/plugins/de.cau.cs.kieler.core.model/src/de/cau/cs/kieler/c ore/model/util/XtendTransformationUtil.java?rev=5980

Cheers,
Hauke

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Re: [Xtend] Lists in JAVA extensions [message #536983 is a reply to message #536931]

Mon, 31 May 2010 19:08

Sven Efftinge

Messages: 1823
Registered: July 2009

Senior Member

Mmhh.. could it be that the model consists of instances of a different
EPackage? I mean a different instance, maybe a dynamic?

Hauke Fuhrmann schrieb:
> Sven Efftinge schrieb:
>> What makes this type 'custom' (i.e. special)?
>
> Well, its some instance object of my metamodel. So it's not really
> special. But it's not a primitive.
>
>> What kind of meta model do you use? I suspect that you face the
>> problem when running the generator. If that is the case, please share
>> the configuration of your workflow, especially the metaModel part.
>
> I call it from a Java plugin in a command handler. If you want to see it:
>
> http://rtsys.informatik.uni-kiel.de/trac/kieler/browser/trun k/plugins/de.cau.cs.kieler.core.model/src/de/cau/cs/kieler/c ore/model/util/XtendTransformationUtil.java?rev=5980
>
>
> Cheers,
> Hauke

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