dxvectoriterator.java

Java的面向对象数据库系统的源代码

// You can redistribute this software and/or modify it under the terms of
// the Ozone Library License version 1 published by ozone-db.org.
//
// The original code and portions created by SMB are
// Copyright (C) 1997-@year@ by SMB GmbH. All rights reserved.
//
// $Id: DxVectorIterator.java,v 1.1 2001/12/18 10:31:30 per_nyfelt Exp $

package org.ozoneDB.DxLib;

import java.util.*;

/**
 * 
 * 
 * @author <a href="http://www.softwarebuero.de/">SMB</a>
 * @version $Revision: 1.1 $Date: 2001/12/18 10:31:30 $
 */
public final class DxVectorIterator extends DxAbstractIterator {
    
    final static long serialVersionUID = 1L;

    DxVectorCollection	coll;
    
    Vector		vector;
    
    int			currentIndex;
    
    Object		currentObject;
    
    
    /**
     */
    public DxVectorIterator( DxVectorCollection _coll ) {
        coll = _coll;
        vector = coll.internalVector();
        reset();
    }
    
    
    /**
     */
    public Object object() {
        return currentObject;
    } 
    
    
    /**
     */
    public Object next() {
        if (atFirstObject) {
            atFirstObject = false;
        } else {
            try {
                //skip null elements
                while ((currentObject = vector.elementAt( ++currentIndex )) == null);
            } catch (ArrayIndexOutOfBoundsException e) {
                //object returns null if currentIndex exceeds vector size
                currentObject = null;
            }
        } 
        return currentObject;
    } 
    
    
    /**
     */
    public void reset() {
        atFirstObject = true;
        objectRemoved = false;
        currentIndex = 0;
        currentObject = currentIndex < vector.size() ? vector.elementAt( currentIndex ) : null;
    } 
    
    
    /**
     */
    public synchronized Object removeObject() {
        Object answer = vector.elementAt( currentIndex );
        //decrement index to point to the same index after next()
        vector.removeElementAt( currentIndex-- );
        coll.decCounter();
        return answer;
    }
}