Bug 519368 - Throw NoSuchElementException instead of NPE

If the resource is missing from the given graph in the triplestore.

Change-Id: Ic2ec0f2632b0e8b8ffaad1ae57de95be15ff8a4b
Signed-off-by: Andrii Berezovskyi <andriib@kth.se>

1 files changed, 8 insertions, 1 deletions

diff --git a/org.eclipse.lyo.tools.store/src/main/java/org/eclipse/lyo/tools/store/internals/SparqlStoreImpl.java b/org.eclipse.lyo.tools.store/src/main/java/org/eclipse/lyo/tools/store/internals/SparqlStoreImpl.java
index f5e9b12..f766903 100644
--- a/org.eclipse.lyo.tools.store/src/main/java/org/eclipse/lyo/tools/store/internals/SparqlStoreImpl.java
+++ b/org.eclipse.lyo.tools.store/src/main/java/org/eclipse/lyo/tools/store/internals/SparqlStoreImpl.java
@@ -244,7 +244,14 @@ public class SparqlStoreImpl implements Store {
             final URI resourceUri, final Class<T> clazz)
             throws NoSuchElementException, StoreAccessException, ModelUnmarshallingException {
         final Model model = getJenaModelForSubject(namedGraphUri, resourceUri);
-        return getResourcesFromModel(model, clazz).get(0);
+        final List<T> modelResources = getResourcesFromModel(model, clazz);
+        if (modelResources == null || modelResources.isEmpty()) {
+            throw new NoSuchElementException(
+                    "Empty Jena model for the subject " + resourceUri + ". Use resourceExists(g," +
+                            "r) method to check for resource existence before calling this method" +
+                            ".");
+        }
+        return modelResources.get(0);
     }
 
     @Override