code: /**
   * Created on 19. September 2004, 00:19
   *
   * Copyright (c) 2004-2005, Olaf Landsiedel, Protocol Engineering and
   * Distributed Systems, University of Tuebingen
   * All rights reserved.
   *
   * Redistribution and use in source and binary forms, with or without
   * modification, are permitted provided that the following conditions
   * are met:
   *
   * Redistributions of source code must retain the above copyright notice,
   * this list of conditions and the following disclaimer.
   *
   * Redistributions in binary form must reproduce the above copyright
   * notice, this list of conditions and the following disclaimer in the
   * documentation and/or other materials provided with the distribution.
   *
   * Neither the name of the Protocol Engineering and Distributed Systems
   * Group, the name of the University of Tuebingen nor the names of its
   * contributors may be used to endorse or promote products derived from
   * this software without specific prior written permission.
   *
   * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
   * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
   * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
   * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
   * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
   * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
   * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
   * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
   * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
   * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
   * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
   */
  
  package avrora.sim.energy;
  
  import java.util.LinkedList;
  
  /**
   * implementation of energy control handles subscription of monitors and consumers
   *
   * @author Olaf Landsiedel
   */
  public class EnergyControl {
  
      //consumer list
      // e.g. list of devices which consume energy
      public final LinkedList<Energy> consumer;
  
      //list of monitors which want to be informed about
      //energy consumption
      private final LinkedList<EnergyObserver> subscriber;
      private boolean active;
  
      public EnergyControl() {
          consumer = new LinkedList<Energy>();
          subscriber = new LinkedList<EnergyObserver>();
      }
  
      /**
       * add energy monitor
       *
       * @param energyMonitor monitor
       */
      public void subscribe(EnergyObserver energyMonitor) {
          subscriber.add(energyMonitor);
      }
  
      /**
       * get list of consumers
       *
       * @return consumer list
       */
      public LinkedList<Energy> getConsumers() {
          return consumer;
      }
  
      /**
       * update the state of a device
       *
       * @param energy the energy model of the device
       */
      public void stateChange(Energy energy) {
          for (EnergyObserver eo : subscriber) {
              eo.stateChange(energy);
          }
      }
  
      public void activate() {
          if (!active) {
              active = true;
              for (Energy en : consumer) {
                  en.activate();
              }
          }
      }
  
      public void addConsumer(Energy energy) {
          consumer.add(energy);
          if (active) energy.activate();
      }
  }
  