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| author | Tom Tromey <tromey@gcc.gnu.org> | 2005-07-16 00:30:23 +0000 |
|---|---|---|
| committer | Tom Tromey <tromey@gcc.gnu.org> | 2005-07-16 00:30:23 +0000 |
| commit | f911ba985aa7fe0096c386c5be385ac5825ea527 (patch) | |
| tree | a0b991cf5866ae1d616639b906ac001811d74508 /libjava/classpath/java/io/Externalizable.java | |
| parent | 6f4434b39b261de5317dc81ddfdd94d2e1d62b11 (diff) | |
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Initial revision
From-SVN: r102074
Diffstat (limited to 'libjava/classpath/java/io/Externalizable.java')
| -rw-r--r-- | libjava/classpath/java/io/Externalizable.java | 107 |
1 files changed, 107 insertions, 0 deletions
diff --git a/libjava/classpath/java/io/Externalizable.java b/libjava/classpath/java/io/Externalizable.java new file mode 100644 index 0000000..113c19f --- /dev/null +++ b/libjava/classpath/java/io/Externalizable.java @@ -0,0 +1,107 @@ +/* Externalizable.java -- Interface for saving and restoring object data + Copyright (C) 1998 Free Software Foundation, Inc. + +This file is part of GNU Classpath. + +GNU Classpath is free software; you can redistribute it and/or modify +it under the terms of the GNU General Public License as published by +the Free Software Foundation; either version 2, or (at your option) +any later version. + +GNU Classpath 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 for more details. + +You should have received a copy of the GNU General Public License +along with GNU Classpath; see the file COPYING. If not, write to the +Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA +02110-1301 USA. + +Linking this library statically or dynamically with other modules is +making a combined work based on this library. Thus, the terms and +conditions of the GNU General Public License cover the whole +combination. + +As a special exception, the copyright holders of this library give you +permission to link this library with independent modules to produce an +executable, regardless of the license terms of these independent +modules, and to copy and distribute the resulting executable under +terms of your choice, provided that you also meet, for each linked +independent module, the terms and conditions of the license of that +module. An independent module is a module which is not derived from +or based on this library. If you modify this library, you may extend +this exception to your version of the library, but you are not +obligated to do so. If you do not wish to do so, delete this +exception statement from your version. */ + + +package java.io; + +/** + * This interface provides a way that classes can completely control how + * the data of their object instances are written and read to and from + * streams. It has two methods which are used to write the data to a stream + * and to read the data from a stream. The read method must read the data + * in exactly the way it was written by the write method. + * <p> + * Note that classes which implement this interface must take into account + * that all superclass data must also be written to the stream as well. + * The class implementing this interface must figure out how to make that + * happen. + * <p> + * This interface can be used to provide object persistence. When an + * object is to be stored externally, the <code>writeExternal</code> method is + * called to save state. When the object is restored, an instance is + * created using the default no-argument constructor and the + * <code>readExternal</code> method is used to restore the state. + * + * @author Aaron M. Renn (arenn@urbanophile.com) + */ +public interface Externalizable extends Serializable +{ + /** + * This method restores an object's state by reading in the instance data + * for the object from the passed in stream. Note that this stream is not + * a subclass of <code>InputStream</code>, but rather is a class that + * implements + * the <code>ObjectInput</code> interface. That interface provides a + * mechanism for + * reading in Java data types from a stream. + * <p> + * Note that this method must be compatible with <code>writeExternal</code>. + * It must read back the exact same types that were written by that + * method in the exact order they were written. + * <p> + * If this method needs to read back an object instance, then the class + * for that object must be found and loaded. If that operation fails, + * then this method throws a <code>ClassNotFoundException</code> + * + * @param in An <code>ObjectInput</code> instance for reading in the object + * state + * + * @exception ClassNotFoundException If the class of an object being + * restored cannot be found + * @exception IOException If any other error occurs + */ + void readExternal(ObjectInput in) + throws ClassNotFoundException, IOException; + + /** + * This method is responsible for writing the instance data of an object + * to the passed in stream. Note that this stream is not a subclass of + * <code>OutputStream</code>, but rather is a class that implements the + * <code>ObjectOutput</code> interface. That interface provides a + * number of methods + * for writing Java data values to a stream. + * <p> + * Not that the implementation of this method must be coordinated with + * the implementation of <code>readExternal</code>. + * + * @param out An <code>ObjectOutput</code> instance for writing the + * object state + * + * @exception IOException If an error occurs + */ + void writeExternal(ObjectOutput out) throws IOException; +} |