/*
* Copyright (C) 2016 Álinson Santos Xavier <isoron@gmail.com>
*
* This file is part of Loop Habit Tracker.
*
* Loop Habit Tracker is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by the
* Free Software Foundation, either version 3 of the License, or (at your
* option) any later version.
*
* Loop Habit Tracker 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 this program. If not, see <http://www.gnu.org/licenses/>.
*/
package org.isoron.uhabits.models;
import java.util.*;
/**
* A ModelObservable allows objects to subscribe themselves to it and receive
* notifications whenever the model is changed.
*/
public class ModelObservable
{
private List<Listener> listeners;
/**
* Creates a new ModelObservable with no listeners.
*/
public ModelObservable()
{
super();
listeners = new LinkedList<>();
}
/**
* Adds the given listener to the observable.
*
* @param l the listener to be added.
*/
public void addListener(Listener l)
{
listeners.add(l);
}
/**
* Notifies every listener that the model has changed.
* <p>
* Only models should call this method.
*/
public void notifyListeners()
{
for (Listener l : listeners) l.onModelChange();
}
/**
* Removes the given listener.
* <p>
* The listener will no longer be notified when the model changes. If the
* given listener is not subscribed to this observable, does nothing.
*
* @param l the listener to be removed
*/
public void removeListener(Listener l)
{
listeners.remove(l);
}
/**
* Interface implemented by objects that want to be notified when the model
* changes.
*/
public interface Listener
{
/**
* Called whenever the model associated to this observable has been
* modified.
*/
void onModelChange();
}
}