objid.java

数据结构及算法 对于参加ACM的学生有一定帮助 里面有详细的解答

//
//  Unified Library Application
//  Case study in Unified Modeling Language Toolkit
//
//  ObjId.java: represents a object id, a class that works as
//  "pointer" to any persistent object in the system.
//
//  Copyright (c) 1998 John Wiley & Sons, Inc. All rights reserved.
//  Reproduction or translations of this work beyond that permitted
//  in Section 117 of the 1976 United States Copyright Act without
//  the express written permission of the copyright owner is unlawful.
//  Requests for further information should be addressed to Permissions
//  Department, John Wiley & Sons, Inc. The purchaser may make back-up
//  copies for his/her own use only and not for distribution or resale.
//  The Publisher assumes no responsibility for errors, omissions, or
//  damages, caused by the use of these programs of from the use of the
//  information contained herein.

package util;

import java.io.*;

public class ObjId
{
    private String classname;
    private int number;
    public ObjId()
    {
        classname = "NotSet";
        number = 0;
    }
    public ObjId(String name, int num)
    {
        classname = name;
        number = num;
    }
    public String getName()
    {
        return classname;
    }
    public int getId()
    {
        return number;
    }
    public boolean equals(Object obj)
    {
        if (!obj.getClass().getName().equals("util.ObjId"))
            return false;
        ObjId comp = (ObjId) obj;
        if (classname.equals(comp.classname) &&
            number == comp.number)
            return true;
        else
            return false;
    }
    public void write(RandomAccessFile out)
        throws IOException
    {
        out.writeUTF(classname);
        out.writeInt(number);
    }
    public void read(RandomAccessFile in)
        throws IOException
    {
        classname = in.readUTF();
        number = in.readInt();
    }
}