dxabstractcollection.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: DxAbstractCollection.java,v 1.1 2001/12/18 10:31:30 per_nyfelt Exp $

package org.ozoneDB.DxLib;

import org.ozoneDB.io.stream.ResolvingObjectInputStream;

import java.io.*;


/**
 * Common super class of all collection classes.
 */
public abstract class DxAbstractCollection extends DxObject implements DxCollection, Externalizable {

    final static long serialVersionUID = 2L;


    public DxAbstractCollection() {
    }

    /**
     * Construct the collection out of an array of objects.
     */
    //    public DxAbstractCollection (Object[] objs) {
    //        for (int i=0; i<objs.length; i++)
    //            add (objs[i]);
    //        }


    public Object clone( DxCollection newInstance ) {
        try {
            DxIterator it = iterator();
            Object obj;
            while ((obj = it.next()) != null) {
                newInstance.add( obj );
            }
            return newInstance;
        } catch (Exception e) {
            throw new RuntimeException( e.toString() );
        }
    }


    /**
     * erzeugt einen clone der collection und der objekte;
     * Achtung: alle objekte in der collection muessen DxCompatible sein
     */
    public DxCollection valueClone() {
        try {
            DxCollection coll = (DxCollection)getClass().newInstance();
            DxIterator it = iterator();
            while (it.next() != null) {
                Object obj = it.object();

                if (obj instanceof DxCompatible) {
                    coll.add( ((DxCompatible)obj).clone() );
                } else if (obj instanceof Serializable) {

                    ByteArrayOutputStream bout = new ByteArrayOutputStream( 4096 );
                    ObjectOutputStream out = new ObjectOutputStream( bout );
                    out.writeObject( obj );
                    out.close();

                    ObjectInputStream in = new ResolvingObjectInputStream( new ByteArrayInputStream( bout.toByteArray() ) );
                    coll.add( in.readObject() );
                } else {

                    throw new CloneNotSupportedException();
                }
            }
            return coll;
        } catch (Exception e) {
            throw new RuntimeException( e.toString() );
        }
    }


    public Object[] toArray() {
        Object[] result = new Object[count()];
        DxIterator it = iterator();
        Object obj;
        for (int i = 0; (obj = it.next()) != null; i++) {
            result[i] = obj;
        }
        return result;
    }


    /**
     * Compares two collections for equality.
     * You have to override this method in the implementation of an actual
     * collections in order to provide another behaviour than the one implemented in
     * Objects.equals().
     */
    public boolean equals( Object obj ) {
        return super.equals( obj );

    //        if (obj instanceof DxCollection && obj != null) {
    //
    //            if (this == obj)
    //                return true;
    //
    //            boolean answer = true;
    //            DxIterator it = iterator();
    //            while (it.next() != null) {
    //                if (!((DxCollection)obj).contains (it.object())) {
    //                    answer = false;
    //                    break;
    //                    }
    //                }
    //            if (answer) {
    //                it = ((DxCollection)obj).iterator();
    //                while (it.next() != null) {
    //                    if (!contains (it.object())) {
    //                        answer = false;
    //                        break;
    //                        }
    //                    }
    //                }
    //            return answer;
    //            }
    //        else
    //            return false;
    }


    public synchronized boolean addAll( DxCollection coll ) {
        boolean answer = false;
        DxIterator it = coll.iterator();
        Object obj;
        while ((obj = it.next()) != null) {
            if (add( obj )) {
                answer = true;
            }
        }
        return answer;
    }


    public synchronized boolean addAll( Object[] objs ) {
        boolean answer = false;
        for (int i = 0; i < objs.length; i++) {
            if (add( objs[i] )) {
                answer = true;
            }
        }
        return answer;
    }


    /**
     * Remove the first occurence of an object that equals the the
     * specified object.
     */
    public synchronized boolean remove( Object obj ) {
        boolean answer = false;
        DxIterator it = iterator();
        Object cursor;
        while ((cursor = it.next()) != null) {
            if (obj.equals( cursor )) {
                it.removeObject();
                answer = true;
            }
        }
        return answer;
    }


    public synchronized boolean removeAll( DxCollection coll ) {
        boolean answer = false;
        if (!coll.isEmpty() && !isEmpty()) {
            DxIterator it = coll.iterator();
            Object obj;
            while ((obj = it.next()) != null) {
                if (remove( obj )) {
                    answer = true;
                }
            }
        }
        return answer;
    }


    /**
     * Returns true is this collection contains an object that equals
     * to the specified object.
     */
    public boolean contains( Object obj ) {
        DxIterator it = iterator();
        Object cursor;
        while ((cursor = it.next()) != null) {
            if (obj.equals( cursor )) {
                return true;
            }
        }
        return false;
    }


    public boolean containsAll( DxCollection coll ) {
        DxIterator it = coll.iterator();
        Object cursor;
        while ((cursor = it.next()) != null) {
            if (!contains( cursor )) {
                return false;
            }
        }
        return true;
    }


    public void writeExternal( ObjectOutput out ) throws IOException {
        // System.out.println (getClass().getName() + ".writeExternal()...");
        out.writeInt( count() );
        DxIterator it = iterator();
        Object obj;
        while ((obj = it.next()) != null) {
            out.writeObject( obj );
        }
    }


    public synchronized void readExternal( ObjectInput in ) throws IOException, ClassNotFoundException {
        int count = in.readInt();
        for (; count > 0; count--) {
            add( in.readObject() );
        }
    }

}