dxlistiterator.java

用Java写的面相对象的数据库管理系统

// 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) 1997-2000 by SMB GmbH. All rights reserved.
//
// $Id: DxListIterator.java,v 1.6 2000/10/28 16:55:14 daniela Exp $

package org.ozoneDB.DxLib;

/**
 * 
 * 
 * @author <a href="http://www.softwarebuero.de/">SMB</a>
 * @version $Revision: 1.6 $Date: 2000/10/28 16:55:14 $
 */
public class DxListIterator extends DxAbstractIterator {
    
    final static long serialVersionUID = 1L;
    
    DxListCollection list;
    DxListNode node;
    Object currentObject;
    
    
    /**
     */
    public DxListIterator( DxListCollection _list ) {
        list = _list;
        reset();
    }
    
    
    /**
     */
    public Object object() {
        return currentObject;
    } 
    
    
    /**
     */
    public Object next() {
        if (atFirstObject) {
            atFirstObject = false;
        } else {
            if (currentObject != null && !objectRemoved) {
                node = node.next();
            } 
            objectRemoved = false;
        } 
        currentObject = node != null ? node.data() : null;
        return currentObject;
    } 
    
    
    /**
     */
    public void reset() {
        node = list.head().next();
        atFirstObject = true;
        objectRemoved = false;
        currentObject = null;
    } 
    
    
    /**
     */
    public Object removeObject() {
        Object answer = currentObject;
        if (currentObject != null && !objectRemoved) {
            DxListNode delNode = node;
            node = node.next();
            delNode.remove();
            objectRemoved = true;
            list.decCounter();
            currentObject = null;
        } 
        return answer;
    } 
}