com.exigen.ie.constrainer.Observer Maven / Gradle / Ivy
package com.exigen.ie.constrainer;
///////////////////////////////////////////////////////////////////////////////
/*
* Copyright Exigen Group 1998, 1999, 2000
* 320 Amboy Ave., Metuchen, NJ, 08840, USA, www.exigengroup.com
*
* The copyright to the computer program(s) herein
* is the property of Exigen Group, USA. All rights reserved.
* The program(s) may be used and/or copied only with
* the written permission of Exigen Group
* or in accordance with the terms and conditions
* stipulated in the agreement/contract under which
* the program(s) have been supplied.
*/
///////////////////////////////////////////////////////////////////////////////
//: Observer.java
/**
* An abstract class for the observer in the observer-subject (or subscriber-publisher) design pattern.
*/
public abstract class Observer implements EventOfInterest.Constants, java.io.Serializable
{
/**
* Returns true if the "event" is the one this observer is interested in.
*
* @return true if the "event" is the one this observer is interested in.
*
* @param event EventOfInterest.
*/
final public boolean interestedIn(EventOfInterest event)
{
return (subscriberMask() & event.type()) != 0;
}
/**
* Returns the subscriber mask for this observer.
*
* @return the subscriber mask for this observer.
*/
public abstract int subscriberMask();
/**
* Sets the subscriber mask for this observer.
*/
public void subscriberMask(int mask, Subject subj) {}
/**
* Returns the object that owns this observer.
*/
public abstract Object master();
/**
* Called as a notification about an "event" that occured whith the "subject".
* This observer should be subscribed to the corresponding event type for this "subject".
*/
public abstract void update(Subject subject, EventOfInterest event)
throws Failure;
}