85 lines
2.3 KiB
Java
85 lines
2.3 KiB
Java
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/*
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File: OrbitPositions.java
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University of Applied Science Berne,HTA-Biel/Bienne,
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Computer Science Department.
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Diploma thesis J3D Solar System Simulator
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Originally written by Marcel Portner & Bernhard Hari (c) 2000
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CVS - Information :
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$Header: /var/cvsreps/projects/c450/2000/sss3d/source_diploma/sss3d/utils/observer/OrbitPositions.java,v 1.3 2000/12/13 13:42:04 portm Exp $
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$Author: portm $
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$Date: 2000/12/13 13:42:04 $
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$State: Exp $
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*/
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package sss3d.utils.observer;
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import java.util.*;
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/**
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* Abstract class OrbitPositions is part of the position observer - defined
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* by the observer pattern.
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* References : E.Gamma; Design Patterns ISBN 0-201-63361-2, Addison Wesley, 1995<br>
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* OrbitPositions knows its observers and provides an interface for attaching and
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* detaching Observer objects.
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*
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* @author Marcel Portner & Bernhard Hari
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* @version $Revision: 1.3 $
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* @see PositionObserver
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* @see ObjectsPositions
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*/
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abstract public class OrbitPositions {
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protected java.util.Vector observers; // list containing all observers
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/**
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* Creates an object of OrbitPositions witch holds a vector of
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* all attached observers.
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*/
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public OrbitPositions() {
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observers = new Vector();
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}
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/**
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* Attaches an observer to the vector observers.
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*
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* @param observer position observer to attach
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*/
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public void attach(PositionObserver observer) {
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observers.addElement(observer);
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}
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/**
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* Detaches an observer from the vector observers.
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*
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* @param observer removes the position observer from the list
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*/
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public void detach(PositionObserver observer) {
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observers.removeElement(observer);
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}
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/**
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* Notifys an observer given by the argument.
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*
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* @param id id from observer inside the list
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*/
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public void notifyObservers(String id) {
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PositionObserver po;
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Enumeration e = observers.elements();
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while(e.hasMoreElements()) {
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// get identification from every object
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// and update the positions...
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po = (PositionObserver)e.nextElement();
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if( (po.getId()).equals(id) ){
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po.update(this);
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}
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}
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}
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}
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