book.java

jdk 6.0的api文档．．．很难找到哦

/*
 * Copyright 2002 Sun Microsystems, Inc. All  Rights Reserved.
 *  
 * Redistribution and use in source and binary forms, with or 
 * without modification, are permitted provided that the following 
 * conditions are met:
 * 
 * -Redistributions of source code must retain the above copyright  
 *  notice, this list of conditions and the following disclaimer.
 * 
 * -Redistribution in binary form must reproduce the above copyright 
 *  notice, this list of conditions and the following disclaimer in 
 *  the documentation and/or other materials provided with the 
 *  distribution.
 *  
 * Neither the name of Sun Microsystems, Inc. or the names of 
 * contributors may be used to endorse or promote products derived 
 * from this software without specific prior written permission.
 * 
 * This software is provided "AS IS," without a warranty of any 
 * kind. ALL EXPRESS OR IMPLIED CONDITIONS, REPRESENTATIONS AND 
 * WARRANTIES, INCLUDING ANY IMPLIED WARRANTY OF MERCHANTABILITY, 
 * FITNESS FOR A PARTICULAR PURPOSE OR NON-INFRINGEMENT, ARE HEREBY 
 * EXCLUDED. SUN AND ITS LICENSORS SHALL NOT BE LIABLE FOR ANY 
 * DAMAGES OR LIABILITIES  SUFFERED BY LICENSEE AS A RESULT OF OR 
 * RELATING TO USE, MODIFICATION OR DISTRIBUTION OF THE SOFTWARE OR 
 * ITS DERIVATIVES. IN NO EVENT WILL SUN OR ITS LICENSORS BE LIABLE 
 * FOR ANY LOST REVENUE, PROFIT OR DATA, OR FOR DIRECT, INDIRECT, 
 * SPECIAL, CONSEQUENTIAL, INCIDENTAL OR PUNITIVE DAMAGES, HOWEVER 
 * CAUSED AND REGARDLESS OF THE THEORY OF LIABILITY, ARISING OUT OF 
 * THE USE OF OR INABILITY TO USE SOFTWARE, EVEN IF SUN HAS BEEN 
 * ADVISED OF THE POSSIBILITY OF SUCH DAMAGES.
 *  
 * You acknowledge that Software is not designed, licensed or 
 * intended for use in the design, construction, operation or 
 * maintenance of any nuclear facility. 
 */

import java.io.*;


/**
 * The Externalizable subclass.
 * Will save the state of its superclass by calling the superclass's 
 * writeExternal and readExternal Methods from within its own writeExternal 
 * and readExternal methods
 */
public class Book extends ReadingMaterial implements Externalizable {

    private int numpages;
    private String name;
    private boolean ishardcover;

    // other relevant information and methods
    // .
    // .
    // .
   
    /** 
     * mandatory public no-arg constructor 
     */
    public Book() { 
	super(); }
  
    public Book(int pages, String n, boolean hardcover, String author,
	 String subject, int yearwritten) {

	super(author, subject, yearwritten);
	numpages = pages;
	name = n;
	ishardcover = hardcover;
    }

    /**
     * Mandatory writeExternal method. 
     * 
     * @serialData Saves state of its superclass by
     *             calling its writeExternal method and 
     *             then save its own fields. Writes numpages field as int,
     *             name field as an object and ishardcover field as a boolean.
     * 
     * @see ReadingMaterial#writeExternal(ObjectOutput)
     */
    public void writeExternal(ObjectOutput out) throws IOException {
	
	// first we call the writeExternal of the superclass as to write
	// all the superclass data fields
	super.writeExternal(out);

	// now we take care of this class's fields
	out.writeInt(numpages);
	out.writeObject(name);
	out.writeBoolean(ishardcover);
    }

    /**
     * Mandatory readExternal method. Will read in the data that we wrote out
     * in the writeExternal method. Restores the state of the superclass 
     * first by calling the superclass's readExternal method. Then, restores 
     * its own fields. These fields MUST BE IN THE SAME ORDER AND TYPE as we
     * wrote them out.
     * By the time, readExternal is called, an object of this class has already
     * been created using the public no-arg constructor, so this method is
     * used to restore the data to all of the fields of the newly created
     * object.
     */
    public void readExternal(ObjectInput in) throws IOException, ClassNotFoundException {

      // first call the superclass external method
    super.readExternal(in);
    
    // now take care of this subclass's fields
    numpages = in.readInt();
    name = (String)in.readObject();
    ishardcover= in.readBoolean();
  }

    /** 
     * Prints out the fields. used for testing!
     */
    public String toString() {
        return("Name: " + name + "\n" + "Author: " + super.getAuthor() + "\n" + "Pages: "
+ numpages + "\n" + "Subject: " + super.getSubject() + "\n" + "Year: " + super.getYearwritten() + "\n" );
    }
}