EventManager.java

package org.rr.jeborker.event;

import java.util.ArrayList;
import java.util.Collections;
import java.util.List;

import org.rr.commons.collection.WeakList;


public class EventManager {

	public static enum EVENT_TYPES {
		EBOOK_ITEM_SELECTION_CHANGE, METADATA_SHEET_SELECTION_CHANGE, METADATA_SHEET_CONTENT_CHANGE, MAIN_TREE_VISIBILITY_CHANGED
	}

	private static WeakList<ApplicationEventListener> weakListenerList = new WeakList<>();

	private static List<ApplicationEventListener> listenerList = Collections.synchronizedList(new ArrayList<ApplicationEventListener>());

	/**
	 * Adds a weak {@link ApplicationEventListener} listener which will be automatically removed if no hard reference exists anywhere.
	 * @param listener The listener instance to be added.
	 */
	public static synchronized void addWeakListener(ApplicationEventListener listener) {
		weakListenerList.add(listener);
	}

	/**
	 * Adds an {@link ApplicationEventListener} to the listener list which is invoked with the {@link #fireEvent(EVENT_TYPES, ApplicationEvent)} method.
	 * @param listener The listener instance to be added.
	 */
	public static synchronized void addListener(ApplicationEventListener listener) {
		listenerList.add(listener);
	}

	public static synchronized void removeListener(ApplicationEventListener listener) {
		weakListenerList.remove(listener);
		listenerList.remove(listener);
	}

	/**
	 * Fires the event with the specified {@link EVENT_TYPES} to all registered listeners.
	 * @param type The type of event to be fired.
	 * @param evt The event.
	 */
	public static synchronized void fireEvent(EVENT_TYPES type, ApplicationEvent evt) {
		weakListenerList.trimToSize();
		for (int i = 0; i < weakListenerList.size(); i++) {
			ApplicationEventListener applicationEventListener = weakListenerList.get(i);
			fireEvent(type, evt, applicationEventListener);
		}
		for (int i = 0; i < listenerList.size(); i++) {
			ApplicationEventListener applicationEventListener = listenerList.get(i);
			fireEvent(type, evt, applicationEventListener);
		}
	}

	/**
	 * executes the specified event on the given {@link ApplicationEventListener}
	 * @param type The type of event to be fired.
	 * @param evt The {@link ApplicationEvent} containing the current application values.
	 * @param listener The listener where the event method should be invoked.
	 */
	private static void fireEvent(EVENT_TYPES type, ApplicationEvent evt, ApplicationEventListener listener) {
		if(type.equals(EVENT_TYPES.EBOOK_ITEM_SELECTION_CHANGE)) {
			listener.ebookItemSelectionChanged(evt);
		} else if(type.equals(EVENT_TYPES.METADATA_SHEET_SELECTION_CHANGE)) {
			listener.metaDataSheetSelectionChanged(evt);
		} else if(type.equals(EVENT_TYPES.METADATA_SHEET_CONTENT_CHANGE)) {
			listener.metaDataSheetContentChanged(evt);
		} else if(type.equals(EVENT_TYPES.MAIN_TREE_VISIBILITY_CHANGED)) {
			listener.mainTreeVisibilityChanged(evt);
		}
	}

}