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| 1 | +/* | |
| 2 | + * Copyright (c) 1996, 2004, Oracle and/or its affiliates. All rights reserved. | |
| 3 | + * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. | |
| 4 | + * | |
| 5 | + * This code is free software; you can redistribute it and/or modify it | |
| 6 | + * under the terms of the GNU General Public License version 2 only, as | |
| 7 | + * published by the Free Software Foundation. Oracle designates this | |
| 8 | + * particular file as subject to the "Classpath" exception as provided | |
| 9 | + * by Oracle in the LICENSE file that accompanied this code. | |
| 10 | + * | |
| 11 | + * This code is distributed in the hope that it will be useful, but WITHOUT | |
| 12 | + * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or | |
| 13 | + * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License | |
| 14 | + * version 2 for more details (a copy is included in the LICENSE file that | |
| 15 | + * accompanied this code). | |
| 16 | + * | |
| 17 | + * You should have received a copy of the GNU General Public License version | |
| 18 | + * 2 along with this work; if not, write to the Free Software Foundation, | |
| 19 | + * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. | |
| 20 | + * | |
| 21 | + * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA | |
| 22 | + * or visit www.oracle.com if you need additional information or have any | |
| 23 | + * questions. | |
| 24 | + */ | |
| 25 | + | |
| 26 | +package java.io; | |
| 27 | + | |
| 28 | +import java.io.ObjectOutput; | |
| 29 | +import java.io.ObjectInput; | |
| 30 | + | |
| 31 | +/** | |
| 32 | + * Only the identity of the class of an Externalizable instance is | |
| 33 | + * written in the serialization stream and it is the responsibility | |
| 34 | + * of the class to save and restore the contents of its instances. | |
| 35 | + * | |
| 36 | + * The writeExternal and readExternal methods of the Externalizable | |
| 37 | + * interface are implemented by a class to give the class complete | |
| 38 | + * control over the format and contents of the stream for an object | |
| 39 | + * and its supertypes. These methods must explicitly | |
| 40 | + * coordinate with the supertype to save its state. These methods supersede | |
| 41 | + * customized implementations of writeObject and readObject methods.<br> | |
| 42 | + * | |
| 43 | + * Object Serialization uses the Serializable and Externalizable | |
| 44 | + * interfaces. Object persistence mechanisms can use them as well. Each | |
| 45 | + * object to be stored is tested for the Externalizable interface. If | |
| 46 | + * the object supports Externalizable, the writeExternal method is called. If the | |
| 47 | + * object does not support Externalizable and does implement | |
| 48 | + * Serializable, the object is saved using | |
| 49 | + * ObjectOutputStream. <br> When an Externalizable object is | |
| 50 | + * reconstructed, an instance is created using the public no-arg | |
| 51 | + * constructor, then the readExternal method called. Serializable | |
| 52 | + * objects are restored by reading them from an ObjectInputStream.<br> | |
| 53 | + * | |
| 54 | + * An Externalizable instance can designate a substitution object via | |
| 55 | + * the writeReplace and readResolve methods documented in the Serializable | |
| 56 | + * interface.<br> | |
| 57 | + * | |
| 58 | + * @author unascribed | |
| 59 | + * @see java.io.ObjectOutputStream | |
| 60 | + * @see java.io.ObjectInputStream | |
| 61 | + * @see java.io.ObjectOutput | |
| 62 | + * @see java.io.ObjectInput | |
| 63 | + * @see java.io.Serializable | |
| 64 | + * @since JDK1.1 | |
| 65 | + */ | |
| 66 | +public interface Externalizable extends java.io.Serializable { | |
| 67 | + /** | |
| 68 | + * The object implements the writeExternal method to save its contents | |
| 69 | + * by calling the methods of DataOutput for its primitive values or | |
| 70 | + * calling the writeObject method of ObjectOutput for objects, strings, | |
| 71 | + * and arrays. | |
| 72 | + * | |
| 73 | + * @serialData Overriding methods should use this tag to describe | |
| 74 | + * the data layout of this Externalizable object. | |
| 75 | + * List the sequence of element types and, if possible, | |
| 76 | + * relate the element to a public/protected field and/or | |
| 77 | + * method of this Externalizable class. | |
| 78 | + * | |
| 79 | + * @param out the stream to write the object to | |
| 80 | + * @exception IOException Includes any I/O exceptions that may occur | |
| 81 | + */ | |
| 82 | + void writeExternal(ObjectOutput out) throws IOException; | |
| 83 | + | |
| 84 | + /** | |
| 85 | + * The object implements the readExternal method to restore its | |
| 86 | + * contents by calling the methods of DataInput for primitive | |
| 87 | + * types and readObject for objects, strings and arrays. The | |
| 88 | + * readExternal method must read the values in the same sequence | |
| 89 | + * and with the same types as were written by writeExternal. | |
| 90 | + * | |
| 91 | + * @param in the stream to read data from in order to restore the object | |
| 92 | + * @exception IOException if I/O errors occur | |
| 93 | + * @exception ClassNotFoundException If the class for an object being | |
| 94 | + * restored cannot be found. | |
| 95 | + */ | |
| 96 | + void readExternal(ObjectInput in) throws IOException, ClassNotFoundException; | |
| 97 | +} | |