dxarraybag.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: DxArrayBag.java,v 1.11 2000/10/28 16:55:14 daniela Exp $

package org.ozoneDB.DxLib;

import java.util.*;
import java.io.*;

/**
 * 
 * 
 * @author <a href="http://www.softwarebuero.de/">SMB</a>
 * @version $Revision: 1.11 $Date: 2000/10/28 16:55:14 $
 */
public class DxArrayBag extends DxAbstractBag implements DxVector, DxVectorCollection {
    
    final static long serialVersionUID = 1L;
    
    private transient Vector vector;
    
    private transient int itemCount;
    
    
    public DxArrayBag() {
        this( 32 );
    }
    
    
    public DxArrayBag( int initSpace ) {
        vector = new Vector( initSpace );
        itemCount = 0;
    }
    
    
    public synchronized boolean addFront( Object obj ) {
        insertAtIndex( obj, 0 );
        return true;
    } 
    
    
    public synchronized boolean addBack( Object obj ) {
        insertAtIndex( obj, size() );
        return true;
    } 
    
    
    /**
     * Sets the component at the specified index of this vector to be the
     * specified object. The previous component at that position is returned.
     * The index must be a value greater than or equal to 0. The size of the
     * array will grow if the specified index is greater than the current size.
     */
    public synchronized Object addAtIndex( Object obj, int index ) {
        if (index >= vector.size()) {
            vector.setSize( index + 1 );
        } 
        Object old = vector.elementAt( index );
        vector.setElementAt( obj, index );
        if (old == null) {
            itemCount++;
        } 
        return old;
    } 
    
    
    public Object elementAtIndex( int index ) {
        return vector.elementAt( index );
    } 
    
    
    /**
     * Sets the component at the specified index to be null. The previous
     * component at that position is returned. The index must be a value
     * greater than or equal to 0 and less than the current size.
     */
    public synchronized Object removeAtIndex( int index ) {
        Object old = vector.elementAt( index );
        vector.setElementAt( null, index );
        if (old != null) {
            itemCount--;
        } 
        return old;
    } 
    
    
    /**
     * Inserts the specified object as a component at the specified index. Each
     * component with an index greater or equal to the specified index is
     * shifted upward to have an index one greater than the value it had
     * previously. The index must be a value greater than or equal to 0 and less
     * than or equal to the current size of the vector.
     */
    public synchronized void insertAtIndex( Object obj, int index ) {
        if (index >= vector.size()) {
            vector.setSize( index );
        } 
        vector.insertElementAt( obj, index );
        itemCount++;
    } 
    
    
    /**
     * Deletes the component at the specified index. Each component in this
     * array with an index greater or equal to the specified index is shifted
     * downward to have an index one smaller than the value it had previously.
     * The index must be a value greater than or equal to 0 and less than the
     * current size.
     */
    public synchronized Object deleteAtIndex( int index ) {
        Object old = vector.elementAt( index );
        if (old != null) {
            itemCount--;
        } 
        vector.removeElementAt( index );
        return old;
    } 
    
    
    public int space() {
        return vector.capacity();
    } 
    
    
    public DxIterator iterator() {
        return new DxVectorIterator( this );
    } 
    
    
    public int count() {
        return itemCount;
    } 
    
    
    public int size() {
        return vector.size();
    } 
    
    
    public boolean isEmpty() {
        return vector.isEmpty();
    } 
    
    
    public synchronized void clear() {
        vector.removeAllElements();
        itemCount = 0;
    } 
    
    
    public Vector internalVector() {
        return vector;
    } 
}