Eclipse e4 EventBroker Map<String, String> NullPointer

Question

I need to send an event with the EventBroker of the eclipse e4 framework. Everything is working ( String, List ...) except a Map Instance.

Map<String, String> test = new LinkedHashMap<>();
test.put("test1", "1");
test.put("test2", "2");

broker.send(EventConstants.EXTENDED_SEARCH_ACTICE_HEADER, test);

And the receiving part

@Inject
@Optional
public void onExtendedSearchActiveHeaderEvent(
        @UIEventTopic(EventConstants.EXTENDED_SEARCH_ACTICE_HEADER) Map<String, String> test) {

    System.out.println(test.size()); 

}

Exception while dispatching event org.osgi.service.event.Event

Followed - of course - a NullPointer Exception

Answer 1

The event broker send (and post) methods treat a Map argument specially and expect it to contain the complete event. This has the side effect that the @UIEventTopic does not think there is any Map data.

To deal with this use:

Map<String, Object> eventMap = new HashMap<String, Object>();

// Your map goes under the `IEventBroker.DATA` key
eventMap.put(IEventBroker.DATA, test);

broker.send(EventConstants.EXTENDED_SEARCH_ACTICE_HEADER, eventMap);