What causes this retainAll exception?
- by Joren
java.lang.UnsupportedOperationException: This operation is not supported on Query Results
at org.datanucleus.store.query.AbstractQueryResult.contains(AbstractQueryResult.java:250)
at java.util.AbstractCollection.retainAll(AbstractCollection.java:369)
at namespace.MyServlet.doGet(MyServlet.java:101)
I'm attempting to take one list I retrieved from a datastore query, and keep only the results which are also in a list I retrieved from a list of keys. Both my lists are populated as expected, but I can't seem to user retainAll on either one of them.
// List<Data> listOne = new ArrayList(query.execute(theQuery));
// DatastoreService ds = DatastoreServiceFactory.getDatastoreService();
// List<Data> listTwo = new ArrayList(ds.get(keys).values());
// listOne.retainAll(listTwo);