abstractenum.java

老外的在线考试

/*
 * Core - Library of useful classes that are used in many CyberDemia projects.
 * Copyright (C) 2003 CyberDemia Research and Services
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Library General Public
 * License as published by the Free Software Foundation; either
 * version 2 of the License, or (at your option) any later version.
 *
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Library General Public License for more details.
 *
 * You should have received a copy of the GNU Library General Public
 * License along with this library; if not, write to the
 * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
 * Boston, MA  02111-1307, USA.
 *
 * See the COPYING file located in the top-level-directory of
 * the archive of this library for complete text of license.
 */
package com.cyberdemia.generic;

/**
* Abstract base class from which all classes that represent enumerated
* values (akin to C++ enum) can be extended.
* <P>Provides all the functionality of a enumerated value class.
* <P>The enumerated value contains an integer code for differentiation
* between values, and an optional name, mainly for display purposes.
* <p>I expect this class to be absolete when JDK 1.5 appears.
 *
 * @author Alexander Yap
 * @version $Revision: 1.4 $ at $Date: 2004/03/22 07:39:44 $ by $Author: alexycyap $
*/
public abstract class AbstractEnum implements java.io.Serializable, Comparable
{

	private Integer m_code=null;
	private String m_name = null;
	private String m_str = null;
	private String m_classNCode = null;

	// Ctors are protected to prevent user instantiation.
	protected AbstractEnum() 
    {
        // Not used.
    }

	/**
	* Creates unamed enumerated value class.
	*/
	protected AbstractEnum(Integer code, String str)
	{
		this(code,str,"Unamed");
	}

	/**
	* Creates named enumerated value class.
	*/
	protected AbstractEnum(Integer code, String str, String name)
	{
		m_code = code;
		m_str = str;
		m_name = name;
		m_classNCode = this.getClass().getName()+code.toString();
		
	}

	/**
	* Gets textual display name of the enumerated value.
	* In multi-lingial application, this may be the message resource key.
	*/
	public String getName()
	{
		return m_name;
	}

	/**
	* Gets textual representation of the programmatic string of this enum
	* object. This is typically used as an abbreviated name.
	*/
	public String getStr()
	{
		return m_str;
	}

	/**
	* Returns the integer code.
	*/
	public Integer getCode()
	{
		return m_code;
	}

	/**
	* Gets textual representation of the integer code of the enumerated value.
	* <P> This is similar to casting a C++ enum to a string stream.
	*/
	public String toString()
	{
		return m_code.toString();
	}

	/**
	* Equality comparison.
	* @return true if obj is a subclass of AbstractEnum with the same
	* code and is of the same class as this enumerated value class.
	*/
	public boolean equals(Object obj)
	{
		if (obj == null)
			return false;
		if (! this.getClass().isInstance(obj))
			return false;

		return (((AbstractEnum)obj).m_code.equals(m_code));
	}

	/**
	* Gets the hashCode which is derived from the integer code and the
	* class name.
	* <P>This makes it unique between different subclasses with the same code.
	*/
	public int hashCode()
	{
		return m_classNCode.hashCode();
	}


	public int compareTo(Object rhs)
	{
		if (rhs instanceof AbstractEnum)
		{
			return m_code.compareTo( ((AbstractEnum)rhs).getCode());
		}
		return -1;
	}

}