/***************************************************************************
* Copyright (C) 2012 by H-Store Project *
* Brown University *
* Massachusetts Institute of Technology *
* Yale University *
* *
* http://hstore.cs.brown.edu/ *
* *
* Permission is hereby granted, free of charge, to any person obtaining *
* a copy of this software and associated documentation files (the *
* "Software"), to deal in the Software without restriction, including *
* without limitation the rights to use, copy, modify, merge, publish, *
* distribute, sublicense, and/or sell copies of the Software, and to *
* permit persons to whom the Software is furnished to do so, subject to *
* the following conditions: *
* *
* The above copyright notice and this permission notice shall be *
* included in all copies or substantial portions of the Software. *
* *
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, *
* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF *
* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. *
* IN NO EVENT SHALL THE AUTHORS BE LIABLE FOR ANY CLAIM, DAMAGES OR *
* OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, *
* ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR *
* OTHER DEALINGS IN THE SOFTWARE. *
***************************************************************************/
package edu.brown.utils;
import java.util.Observable;
/**
* EventObservable
*/
public class EventObservable<T> {
protected class InnerObservable extends Observable {
@Override
public synchronized void setChanged() {
super.setChanged();
}
public EventObservable<T> getEventObservable() {
return (EventObservable.this);
}
};
private final InnerObservable observable;
private int observer_ctr = 0;
public EventObservable() {
this.observable = new InnerObservable();
}
public synchronized void addObserver(EventObserver<T> o) {
if (o != null) {
this.observable.addObserver(o.getObserver());
this.observer_ctr++;
}
}
public synchronized void deleteObserver(EventObserver<T> o) {
this.observable.deleteObserver(o.getObserver());
this.observer_ctr--;
}
public synchronized void deleteObservers() {
this.observable.deleteObservers();
this.observer_ctr = 0;
}
public int countObservers() {
return (this.observer_ctr);
}
/**
* Notifies the Observers that a changed occurred
*
* @param arg
* - the state that changed
*/
public void notifyObservers(T arg) {
this.observable.setChanged();
if (this.observer_ctr > 0)
this.observable.notifyObservers(arg);
}
/**
* Notifies the Observers that a changed occurred
*/
public void notifyObservers() {
this.observable.setChanged();
if (this.observer_ctr > 0)
this.observable.notifyObservers();
}
} // END CLASS