IObserver.java

/*-
 * Copyright © 2009 Diamond Light Source Ltd., Science and Technology
 * Facilities Council Daresbury Laboratory
 *
 * This file is part of GDA.
 *
 * GDA is free software: you can redistribute it and/or modify it under the
 * terms of the GNU General Public License version 3 as published by the Free
 * Software Foundation.
 *
 * GDA 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 General Public License for more
 * details.
 *
 * You should have received a copy of the GNU General Public License along
 * with GDA. If not, see <http://www.gnu.org/licenses/>.
 */

package gda.observable;

/**
 * A general purpose interface for an object to observe an IObservable object. Observing objects must must be added to
 * the IObservable object's list of IObservers by invoking the <IObservable object>.addIObserver() method. Notification
 * from IObservable object is received in the observing objects update() method.
 *
 * @see gda.observable.IObservable
 */
public interface IObserver {

	/**
	 * Called whenever an observed object is changed.
	 *
	 * @param source
	 *            the object being observed
	 * @param arg
	 *            the object specific to the observed object and which representing the change being notified (eg data,
	 *            state etc.)
	 */
	void update(Object source, Object arg);

}