/* * Copyright (c) 2002, Oracle and/or its affiliates. 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 Oracle nor 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 subclass that implements Externalizable.. responsible for * saving the state of its non-Externalizable super class */ class Book extends ReadingMaterial implements Externalizable { int numpages; String name; boolean ishardcover; // other relevant information and methods // . // . // . /* * mandatory public no-arg constructor * if the superclass did not have a no-arg constructor, we would have to * give the regular constructor default values. */ public Book() { super(); } Book(int pages, String n, boolean hardcover, String author, String subject, int yearwritten) { super(author, subject, yearwritten); numpages = pages; name = n; ishardcover = hardcover; } /** * Mandatory writeExernal method. * * @serialData Expicitly saves the supertype's fields and then saves this * class fields. Writes superclass fields in following order: * author as an object, subject as an object, yearwritten * as an integer. Writes class fields in following order: * numpages as an int, name as an Object and ishardcover * as a boolean. */ public void writeExternal(ObjectOutput out) throws IOException { /* * Since the superclass does not implement the Serializable interface * we explicitly do the saving... Since these fields are not private * we can access them directly. If they were private, the superclass * would have to implement get methods that would allow the * subclass this necessary access for proper saving. */ out.writeObject(author); out.writeObject(subject); out.writeInt(yearwritten); // now we take care of this subclass's fields out.writeInt(numpages); out.writeObject(name); out.writeBoolean(ishardcover); } /** * Mandatory readExternal method. Explicitly restores the supertype's * fields and then restores * this class's fields */ public void readExternal(ObjectInput in) throws IOException, ClassNotFoundException { /* * Since the superclass does not implement the Serializable interface * we explicitly do the restoring... Since these fields are not private * we can access them directly. If they were private, the superclass * would have to implement set methods that would allow the * subclass this necessary access for proper restoring. */ author = (String) in.readObject(); subject = (String) in.readObject(); yearwritten = in.readInt(); // now we take care of the 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: " + author + "\n" + "Pages: " + numpages + "\n" + "Subject: " + subject + "\n" + "Year: " + yearwritten + "\n"); } }