| Persisting object as XMI using Ecore model [message #1233182] |
Sat, 18 January 2014 17:15  |
Eclipse User |
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Hello,
I am new to EMF and I have created a simple model and generated Java code from it. Now I need to persist the object values that I set using the technique.
Here is my model code:
<?xml version="1.0" encoding="UTF-8"?>
<ecore:EPackage xmi:version=.....
name="library" nsURI="http:// library/1.0" nsPrefix="library">
<eClassifiers xsi:type="ecore:EClass" name="Book">
<eStructuralFeatures xsi:type="ecore:EAttribute" name="title" eType="ecore:EDataType http://www.eclipse.org/emf/2002/Ecore#//EString"/>
<eStructuralFeatures xsi:type="ecore:EAttribute" name="pages" eType="ecore:EDataType http://www.eclipse.org/emf/2002/Ecore#//EInt"/>
<eStructuralFeatures xsi:type="ecore:EReference" name="author" lowerBound="1"
eType="#//Writer"/>
</eClassifiers>
<eClassifiers xsi:type="ecore:EClass" name="Writer">
<eStructuralFeatures xsi:type="ecore:EAttribute" name="name" eType="ecore:EDataType http://www.eclipse.org/emf/2002/Ecore#//EString"/>
</eClassifiers>
</ecore:EPackage>
And the Java code is generated well. However when I execute the code:
// Initialize the model
LibraryPackage.eINSTANCE.eClass();
// Retrieve the default factory singleton
factory = new LibraryFactoryImpl();
// Create the content of the model via this program
Book book = factory.createBook();
book.setTitle("Title of Book");
book.setPages(200);
Writer author = factory.createWriter();
author.setName("Siddhartha");
book.setAuthor(author);
// Obtain a new resource set
ResourceSet resSet = new ResourceSetImpl();
// Register the default resource factory -- only needed for stand-alone!
resSet.getResourceFactoryRegistry()
.getExtensionToFactoryMap()
.put(Resource.Factory.Registry.DEFAULT_EXTENSION,
new XMIResourceFactoryImpl());
URI fileURI = URI.createFileURI(new File("library.xml")
.getAbsolutePath());
// create a resource
Resource resource = resSet.createResource(fileURI);
// Get the first model element and cast it to the right type, in my
// example everything is hierarchical included in this first node
resource.getContents().add(book);
// resource.getContents().add(webPage);
// now save the content.
try {
resource.save(Collections.EMPTY_MAP);
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
I get an exception: java.lang.NullPointerException
at org.eclipse.emf.ecore.EcorePackage$Literals.<clinit>(EcorePackage.java:5145)
... 20 more
The reason as shown by debugger is, in EcorePackage$Literals:
EClass EATTRIBUTE = eINSTANCE.getEAttribute();
Here the eINSTANCE is NULL.
Could you please help me with this, if I am doing anything wrong.
Thanks in advance.
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| Re: Persisting object as XMI using Ecore model [message #1233451 is a reply to message #1233407] |
Sun, 19 January 2014 12:35  |
| Eclipse User |
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Hi
It is not clear to me how saveModelObject(SaveModelObject.java:34)
relates to your earlier message.
You might find that following
http://wiki.eclipse.org/OCL/ForumNetiquette reduces the need to play
ping pong.
Regards
Ed Willink
On 19/01/2014 14:56, Siddhartha Moitra wrote:
> Hello,
>
> Here is the complete stacktrace. I added the ecore initializing
> statement, but no luck.
>
>
> Exception in thread "main" java.lang.ExceptionInInitializerError
> at
> org.eclipse.emf.ecore.impl.EPackageImpl.eStaticClass(EPackageImpl.java:236)
> at
> org.eclipse.emf.ecore.impl.MinimalEObjectImpl.eClass(MinimalEObjectImpl.java:688)
> at
> org.eclipse.emf.ecore.impl.ENamedElementImpl.eContents(ENamedElementImpl.java:224)
> at
> org.eclipse.emf.ecore.util.EcoreUtil$ProperContentIterator.<init>(EcoreUtil.java:1290)
> at
> org.eclipse.emf.ecore.util.EcoreUtil$4.getChildren(EcoreUtil.java:1201)
> at
> org.eclipse.emf.ecore.util.EcoreUtil$ContentTreeIterator.hasNext(EcoreUtil.java:1452)
> at
> org.eclipse.emf.ecore.resource.impl.ResourceImpl.attached(ResourceImpl.java:844)
> at
> org.eclipse.emf.ecore.resource.impl.ResourceImpl$ContentsEList.inverseAdd(ResourceImpl.java:411)
> at
> org.eclipse.emf.common.notify.impl.NotifyingListImpl.addUnique(NotifyingListImpl.java:312)
> at
> org.eclipse.emf.common.util.AbstractEList.add(AbstractEList.java:301)
> at
> org.eclipse.emf.ecore.impl.EPackageImpl.createResource(EPackageImpl.java:753)
> at
> org.eclipse.emf.ecore.impl.EcorePackageImpl.initializePackageContents(EcorePackageImpl.java:2838)
> at
> org.eclipse.emf.ecore.impl.EcorePackageImpl.init(EcorePackageImpl.java:485)
> at org.eclipse.emf.ecore.EcorePackage.<clinit>(EcorePackage.java:67)
> at
> de.sid.emf.webpage.SaveModelObject.saveModelObject(SaveModelObject.java:34)
> at
> de.sid.emf.webpage.main.SaveLoadModelObjectMain.main(SaveLoadModelObjectMain.java:19)
> Caused by: java.lang.NullPointerException
> at
> org.eclipse.emf.ecore.EcorePackage$Literals.<clinit>(EcorePackage.java:5145)
> ... 16 more
>
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