/*

 * Copyright 1996-2005 Sun Microsystems, Inc.  All Rights Reserved.

 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

 *

 * This code is free software; you can redistribute it and/or modify it

 * under the terms of the GNU General Public License version 2 only, as

 * published by the Free Software Foundation.  Sun designates this

 * particular file as subject to the "Classpath" exception as provided

 * by Sun in the LICENSE file that accompanied this code.

 *

 * This code 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 General Public License

 * version 2 for more details (a copy is included in the LICENSE file that

 * accompanied this code).

 *

 * You should have received a copy of the GNU General Public License version

 * 2 along with this work; if not, write to the Free Software Foundation,

 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

 *

 * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,

 * CA 95054 USA or visit www.sun.com if you need additional information or

 * have any questions.

 */

package java.io;

/**

 * Serializability of a class is enabled by the class implementing the

 * java.io.Serializable interface. Classes that do not implement this

 * interface will not have any of their state serialized or

 * deserialized.  All subtypes of a serializable class are themselves

 * serializable.  The serialization interface has no methods or fields

 * and serves only to identify the semantics of being serializable. <p>

 *

 * To allow subtypes of non-serializable classes to be serialized, the

 * subtype may assume responsibility for saving and restoring the

 * state of the supertype's public, protected, and (if accessible)

 * package fields.  The subtype may assume this responsibility only if

 * the class it extends has an accessible no-arg constructor to

 * initialize the class's state.  It is an error to declare a class

 * Serializable if this is not the case.  The error will be detected at

 * runtime. <p>

 *

 * During deserialization, the fields of non-serializable classes will

 * be initialized using the public or protected no-arg constructor of

 * the class.  A no-arg constructor must be accessible to the subclass

 * that is serializable.  The fields of serializable subclasses will

 * be restored from the stream. <p>

 *

 * When traversing a graph, an object may be encountered that does not

 * support the Serializable interface. In this case the

 * NotSerializableException will be thrown and will identify the class

 * of the non-serializable object. <p>

 *

 * Classes that require special handling during the serialization and

 * deserialization process must implement special methods with these exact

 * signatures: <p>

 *

 * <PRE>

 * private void writeObject(java.io.ObjectOutputStream out)

 *     throws IOException

 * private void readObject(java.io.ObjectInputStream in)

 *     throws IOException, ClassNotFoundException;

 * private void readObjectNoData()

 *     throws ObjectStreamException;

 * </PRE>

 *

 * <p>The writeObject method is responsible for writing the state of the

 * object for its particular class so that the corresponding

 * readObject method can restore it.  The default mechanism for saving

 * the Object's fields can be invoked by calling

 * out.defaultWriteObject. The method does not need to concern

 * itself with the state belonging to its superclasses or subclasses.

 * State is saved by writing the individual fields to the

 * ObjectOutputStream using the writeObject method or by using the

 * methods for primitive data types supported by DataOutput.

 *

 * <p>The readObject method is responsible for reading from the stream and

 * restoring the classes fields. It may call in.defaultReadObject to invoke

 * the default mechanism for restoring the object's non-static and

 * non-transient fields.  The defaultReadObject method uses information in

 * the stream to assign the fields of the object saved in the stream with the

 * correspondingly named fields in the current object.  This handles the case

 * when the class has evolved to add new fields. The method does not need to

 * concern itself with the state belonging to its superclasses or subclasses.

 * State is saved by writing the individual fields to the

 * ObjectOutputStream using the writeObject method or by using the

 * methods for primitive data types supported by DataOutput.

 *

 * <p>The readObjectNoData method is responsible for initializing the state of

 * the object for its particular class in the event that the serialization

 * stream does not list the given class as a superclass of the object being

 * deserialized.  This may occur in cases where the receiving party uses a

 * different version of the deserialized instance's class than the sending

 * party, and the receiver's version extends classes that are not extended by

 * the sender's version.  This may also occur if the serialization stream has

 * been tampered; hence, readObjectNoData is useful for initializing

 * deserialized objects properly despite a "hostile" or incomplete source

 * stream.

 *

 * <p>Serializable classes that need to designate an alternative object to be

 * used when writing an object to the stream should implement this

 * special method with the exact signature: <p>

 *

 * <PRE>

 * ANY-ACCESS-MODIFIER Object writeReplace() throws ObjectStreamException;

 * </PRE><p>

 *

 * This writeReplace method is invoked by serialization if the method

 * exists and it would be accessible from a method defined within the

 * class of the object being serialized. Thus, the method can have private,

 * protected and package-private access. Subclass access to this method

 * follows java accessibility rules. <p>

 *

 * Classes that need to designate a replacement when an instance of it

 * is read from the stream should implement this special method with the

 * exact signature.<p>

 *

 * <PRE>

 * ANY-ACCESS-MODIFIER Object readResolve() throws ObjectStreamException;

 * </PRE><p>

 *

 * This readResolve method follows the same invocation rules and

 * accessibility rules as writeReplace.<p>

 *

 * The serialization runtime associates with each serializable class a version

 * number, called a serialVersionUID, which is used during deserialization to

 * verify that the sender and receiver of a serialized object have loaded

 * classes for that object that are compatible with respect to serialization.

 * If the receiver has loaded a class for the object that has a different

 * serialVersionUID than that of the corresponding sender's class, then

 * deserialization will result in an {@link InvalidClassException}.  A

 * serializable class can declare its own serialVersionUID explicitly by

 * declaring a field named <code>"serialVersionUID"</code> that must be static,

 * final, and of type <code>long</code>:<p>

 *

 * <PRE>

 * ANY-ACCESS-MODIFIER static final long serialVersionUID = 42L;

 * </PRE>

 *

 * If a serializable class does not explicitly declare a serialVersionUID, then

 * the serialization runtime will calculate a default serialVersionUID value

 * for that class based on various aspects of the class, as described in the

 * Java(TM) Object Serialization Specification.  However, it is <em>strongly

 * recommended</em> that all serializable classes explicitly declare

 * serialVersionUID values, since the default serialVersionUID computation is

 * highly sensitive to class details that may vary depending on compiler

 * implementations, and can thus result in unexpected

 * <code>InvalidClassException</code>s during deserialization.  Therefore, to

 * guarantee a consistent serialVersionUID value across different java compiler

 * implementations, a serializable class must declare an explicit

 * serialVersionUID value.  It is also strongly advised that explicit

 * serialVersionUID declarations use the <code>private</code> modifier where

 * possible, since such declarations apply only to the immediately declaring

 * class--serialVersionUID fields are not useful as inherited members. Array

 * classes cannot declare an explicit serialVersionUID, so they always have

 * the default computed value, but the requirement for matching

 * serialVersionUID values is waived for array classes.

 *

 * @author  unascribed

 * @see java.io.ObjectOutputStream

 * @see java.io.ObjectInputStream

 * @see java.io.ObjectOutput

 * @see java.io.ObjectInput

 * @see java.io.Externalizable

 * @since   JDK1.1

 */

public interface Serializable {

}