/**
* Copyright (C) 2001-2017 by RapidMiner and the contributors
*
* Complete list of developers available at our web site:
*
* http://rapidminer.com
*
* This program is free software: you can redistribute it and/or modify it under the terms of the
* GNU Affero General Public License as published by the Free Software Foundation, either version 3
* of the License, or (at your option) any later version.
*
* This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without
* even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Affero General Public License for more details.
*
* You should have received a copy of the GNU Affero General Public License along with this program.
* If not, see http://www.gnu.org/licenses/.
*/
package com.rapidminer.tools;
import java.util.NoSuchElementException;
/**
* Reimplementation of the Java 1.0 Observer pattern. It has some advantages:
* <ol>
* <li>Separation of interface and implementation</li>
* <li>Generics argument to the update method</li>
* <li>and foremost: The update method can be called on the Event Dispatch Thread (EDT) if this is
* desired. If you don't know, what the EDT is, read the Java docs on Swing and synchronization and
* use EDT if you register an observer that updates Swing GUI components.</li>
* <li>synchronization (Sun's implementation may be synchronized, too, but it is not documented)</li>
* <li>defined exception handling.</li>
* </ol>
*
* @author Simon Fischer
* */
public interface Observable<A> {
/**
* Adds an observer that will be notified on the EDT if onEDT is true.
*
* @throws a
* NPE if observer is null.
*/
public void addObserver(Observer<A> observer, boolean onEDT);
/**
* Removes an observer from this observable.
*
* @throws NoSuchElementException
* if observer is not registered with this Observable.
*/
public void removeObserver(Observer<A> observer);
/**
* Same as {@link #addObserver(Observer, boolean), but adds this observer as the first in the
* list.
*/
void addObserverAsFirst(Observer<A> observer, boolean onEDT);
}