Esper convert result to java.util.Map

Question

I am new to Esper, and a created a small program that feeds Esper events in the form of Map.

I have added a listener, and everything works as expected, however, when doing complex queries like count(*) over a time windows, I struggle to get the result back as a java.util.Map. How can I, regardless of query result, get the results as standard Map for further processing?

private class EsperUpdateListener implements UpdateListener {
    public void update(EventBean[] newEvents, EventBean[] oldEvents) {
        System.out.println("Found new event!");
        if(newEvents != null) {
            System.out.println("newEvents (" + newEvents.length + "):");
            for (EventBean e : newEvents) {
                System.out.println("  " + e.toString() + "(" + e.getEventType().getName() + ")");
                System.out.println("    " + e.getUnderlying().toString());

                for (Map.Entry<String,Object> entry : e.getUnderlying().getEntrySet()) {
                    String key = entry.getKey();
                    String val = (String)entry.getValue();
                    System.out.println("    " + key + ": " + val);
                }
            }
        }
        if(oldEvents != null) {
            System.out.println("oldEvents:");
            for (EventBean e : oldEvents) {
                System.out.println("  " + e.toString() + "(" + e.getEventType().getName() + ")");
            }
        }
    }
}

I tried the code above, but it complains that getUnderlying returns an Object, not a map. I tried casting, which kinda sorta works, but not without warnings:

warning: [unchecked] unchecked cast

Map<String,Object> emap = (Map<String,Object>)e.getUnderlying();

Answer 1

When you register an UpdateListener, it receives EventBean instances. The "eventBean.getUnderlying()" returns the representation object and in this case a Map.