Print an EObject? - eclipse-emf

Question

I am writing some eclipse emf code and would like to print the content of an EObject (not store it to disk).
Here is what I try:
public static void print(EObject obj) {
Resource eResource = obj.eResource();
try {
eResource.save(System.out, null);
} catch (IOException e) {
e.printStackTrace();
}
}
but that gives a NullPointerException. I have tried this instead:
public static void print(EObject obj) {
ResourceSet resourceSet = new ResourceSetImpl();
resourceSet.getResourceFactoryRegistry().getProtocolToFactoryMap()
.put("*", new XMIResourceFactoryImpl());
Resource resource = resourceSet.createResource(URI.createURI("dummyfile.xml"));
resource.getContents().add(obj);
try {
resource.save(System.out, null);
} catch (IOException ioe) {
ioe.printStackTrace();
}
}
This works, but is it not possible to print to screen without specifying a dummy URI??

Answer 1

Updated to include EcoreUtil.copy()
Check this code.
Resource res = new XMLResourceImpl ();
res.getContents().add(EcoreUtil.copy(obj));
try {
resource.save(System.out, null);
} catch (IOException ioe) {
ioe.printStackTrace();
}
If that fails then yes you need a dummy URI
Resource res = new XMLResourceImpl (URI.createURI("dummyfile.xml"));
res.getContents().add(EcoreUtil.copy(obj));
try {
resource.save(System.out, null);
} catch (IOException ioe) {
ioe.printStackTrace();
}

Answer 2

Hm when I pass a copy:
Resource res = new XMLResourceImpl ();
res.getContents().add(ECoreUtil.copy(obj));
try {
resource.save(System.out, null);
} catch (IOException ioe) {
ioe.printStackTrace();
}
some of the xmi attributes are not printed. But if I call the above method multiple times and DON't pass a copy I get a NullPointerException. I guess I am not understanding some basic EMF/Containment functionality here?
So my updated question is:
Is it possible to print a FULL EObject model without modifying the content if the model is used in the following code?