AbstractTypedEventSubscriber.java

/**
 * Copyright (c) 2014-2017 by the respective copyright holders.
 * All rights reserved. This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License v1.0
 * which accompanies this distribution, and is available at
 * http://www.eclipse.org/legal/epl-v10.html
 */
package org.eclipse.smarthome.core.events;

import java.util.Set;

import com.google.common.collect.ImmutableSet;

/**
 * The {@link AbstractTypedEventSubscriber} is an abstract implementation of the {@link EventSubscriber} interface which
 * helps to subscribe to a specific event type. To receive an event - casted to the specific event type - the
 * {@link #receiveTypedEvent(T)} method must be implemented. This implementation provides no event filter. To filter
 * events based on the topic or some content the {@link #getEventFilter()} method can be overridden.
 *
 * @author Stefan Bußweiler - Initial contribution
 *
 * @param <T> The specific event type this class subscribes to.
 */
public abstract class AbstractTypedEventSubscriber<T extends Event> implements EventSubscriber {

    private final Set<String> subscribedEventTypes;

    /**
     * Constructs a new typed event subscriber. Must be called in the subclass.
     *
     * @param eventType the event type
     */
    protected AbstractTypedEventSubscriber(String eventType) {
        this.subscribedEventTypes = ImmutableSet.of(eventType);
    }

    @Override
    public Set<String> getSubscribedEventTypes() {
        return subscribedEventTypes;
    }

    @Override
    public EventFilter getEventFilter() {
        return null;
    }

    @SuppressWarnings("unchecked")
    @Override
    public void receive(Event event) {
        receiveTypedEvent((T) event);
    }

    /**
     * Callback method for receiving typed events of type T.
     *
     * @param event the received event
     */
    protected abstract void receiveTypedEvent(T event);

}