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/*
 * Distributed as part of mchange-commons-java 0.2.11
 *
 * Copyright (C) 2015 Machinery For Change, Inc.
 *
 * Author: Steve Waldman 
 *
 * This library is free software; you can redistribute it and/or modify
 * it under the terms of EITHER:
 *
 *     1) The GNU Lesser General Public License (LGPL), version 2.1, as 
 *        published by the Free Software Foundation
 *
 * OR
 *
 *     2) The Eclipse Public License (EPL), version 1.0
 *
 * You may choose which license to accept if you wish to redistribute
 * or modify this work. You may offer derivatives of this work
 * under the license you have chosen, or you may provide the same
 * choice of license which you have been offered here.
 *
 * This software 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.
 *
 * You should have received copies of both LGPL v2.1 and EPL v1.0
 * along with this software; see the files LICENSE-EPL and LICENSE-LGPL.
 * If not, the text of these licenses are currently available at
 *
 * LGPL v2.1: http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html
 *  EPL v1.0: http://www.eclipse.org/org/documents/epl-v10.php 
 * 
 */

package com.mchange.v1.util;

import java.util.*;

public abstract class NumberedObjectCache
{
    ArrayList al = new ArrayList();
    
    public Object getObject(int num) throws Exception
    {
	Object out = null;
	int req_cap = num + 1;
	if (req_cap > al.size())
	    {
		al.ensureCapacity(req_cap * 2);
		for (int i = al.size(), end = req_cap * 2; i < end; ++i)
		    al.add(null);
		out = addToCache(num);
	    }
	else
	    {
		out = al.get(num);
		if (out == null)
		    out = addToCache(num);
	    }
	return out;
    }

    private Object addToCache(int num) throws Exception
    {
	Object out = findObject(num);
	al.set(num, out);
	return out;
    }

    protected abstract Object findObject(int num) throws Exception;
}