dxhashset.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: DxHashSet.java,v 1.8 2000/10/28 16:55:14 daniela Exp $

package org.ozoneDB.DxLib;

import java.util.*;

/**
 * 
 * 
 * @author <a href="http://www.softwarebuero.de/">SMB</a>
 * @version $Revision: 1.8 $Date: 2000/10/28 16:55:14 $
 */
public class DxHashSet extends DxAbstractSet implements DxHashCollection {
    
    final static long serialVersionUID = 1L;
    
    protected Hashtable ht;
    
    
    public DxHashSet() {
        ht = new Hashtable();
    }
    
    
    public DxHashSet( int initSize ) {
        ht = new Hashtable( initSize );
    }
    
    
    public Object clone() {
        DxSet newSet = new DxHashSet( count() );
        return clone( newSet );
    } 
    
    
    public synchronized boolean add( Object obj ) {
        Object old = ht.put( obj, obj );
        if (old != null) {
            ht.put( old, old );
            return false;
        } else {
            return true;
        } 
    } 
    
    
    public synchronized boolean remove( Object obj ) {
        Object old = ht.remove( obj );
        return old != null;
    } 
    
    
    public boolean contains( Object obj ) {
        return ht.containsKey( obj );
    } 
    
    
    public DxIterator iterator() {
        return new DxHashIterator( this );
    } 
    
    
    public int count() {
        return ht.size();
    } 
    
    
    public boolean isEmpty() {
        return ht.isEmpty();
    } 
    
    
    public synchronized void clear() {
        ht.clear();
    } 
    
    
    public Hashtable internalHashtable() {
        return ht;
    } 
}