Ptidej-v5.2-master/POM Tests/data/ArgoUML_0.28/src/org/argouml/model/mdr/CollectionHelper.java
// $Id: CollectionHelper.java 16356 2008-12-14 23:32:49Z tfmorris $
// Copyright (c) 2006 The Regents of the University of California. All
// Rights Reserved. Permission to use, copy, modify, and distribute this
// software and its documentation without fee, and without a written
// agreement is hereby granted, provided that the above copyright notice
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package org.argouml.model.mdr;

import java.util.ArrayList;
import java.util.Collection;
import java.util.Iterator;

/**
 * Static utility methods for dealing with collections.
 * 
 * @author Tom Morris
 */
public class CollectionHelper {

    /**
     * Update a collection using a minimal update strategy and updating the
     * collection in place. This can be used with the JMI "live" semantic
     * collections to update the model in place. Order of processing is to first
     * remove all obsolete elements from the collection and then add all new
     * elements.
     * 
     * @param base
     *            the base collection to be updated
     * @param updates
     *            desired end state of collection
     */
    static void update(Collection base, Collection updates) {
        if (updates == null) {
            base.clear();
            return;
        }
        Collection toBeRemoved = new ArrayList();
        Collection toBeAdded = new ArrayList();

        Iterator oldIt = base.iterator();
        while (oldIt.hasNext()) {
            Object obj = oldIt.next();
            if (!updates.contains(obj)) {
                toBeRemoved.add(obj);
            }
        }
        Iterator newIt = updates.iterator();
        while (newIt.hasNext()) {
            Object obj = newIt.next();
            if (!base.contains(obj)) {
                toBeAdded.add(obj);
            }
        }
        
        base.removeAll(toBeRemoved);
        base.addAll(toBeAdded);
    }

}
