/* ObjectId.java -- object IDs   Copyright (C) 2005 Free Software FoundationThis file is part of GNU Classpath.GNU Classpath is free software; you can redistribute it and/or modifyit under the terms of the GNU General Public License as published bythe 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, butWITHOUT ANY WARRANTY; without even the implied warranty ofMERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNUGeneral Public License for more details.You should have received a copy of the GNU General Public Licensealong with GNU Classpath; see the file COPYING.  If not, write to theFree Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA02110-1301 USA.Linking this library statically or dynamically with other modules ismaking a combined work based on this library.  Thus, the terms andconditions of the GNU General Public License cover the wholecombination.As a special exception, the copyright holders of this library give youpermission to link this library with independent modules to produce anexecutable, regardless of the license terms of these independentmodules, and to copy and distribute the resulting executable underterms of your choice, provided that you also meet, for each linkedterms of your choice, provided that you also meet, for each linkedindependent module, the terms and conditions of the license of thatmodule.  An independent module is a module which is not derived fromor based on this library.  If you modify this library, you may extendthis exception to your version of the library, but you are notobligated to do so.  If you do not wish to do so, delete thisexception statement from your version. */package gnu.classpath.jdwp.id;import gnu.classpath.jdwp.JdwpConstants;import gnu.classpath.jdwp.exception.InvalidObjectException;import java.io.DataOutputStream;import java.io.IOException;/** * This is a base class for all ObjectID-like entities in JDWP, * inculding Objects, ClassObject, ClassLoader, Thread, ThreadGroup, * etc. * * @author Keith Seitz  <keiths@redhat.com> */public class ObjectId  extends JdwpId{  /**   * The object class that this id represents   */  public static final Class typeClass = Object.class;  // Handle to disable garbage collection  private Object _handle;  /**   * Constructs a new <code>ObjectId</code>   */  public ObjectId ()  {    super (JdwpConstants.Tag.OBJECT);  }  /**   * Constructs a new <code>ObjectId</code> of the   * given type.   *   * @param  tag  the tag of this type of object ID   */  public ObjectId (byte tag)  {    super (tag);  }  /**   * Returns the size of this id type   */  public int size ()  {    return 8;  }  /**   * Returns the object referred to by this ID   *   * @returns the object   * @throws InvalidObjectException if the object was garbage collected   *           or is invalid   */  public Object getObject ()    throws InvalidObjectException  {    Object obj = _reference.get ();    if (obj == null)      throw new InvalidObjectException (_id);    return obj;  }  /**   * Writes the id to the stream   *   * @param outStream  the stream to which to write   * @throws IOException  when an error occurs on the <code>OutputStream</code>   */  public void write (DataOutputStream outStream)    throws IOException  {    // All we need to do is write out our id as an 8-byte integer    outStream.writeLong (_id);  }  /**   * Disable garbage collection on object   */  public void disableCollection ()    throws InvalidObjectException  {    _handle = getObject ();  }  /**   * Enable garbage collection on object   */  public void enableCollection ()  {    _handle = null;  }}