1 /* ObjectId.java -- object IDs 2 Copyright (C) 2005, 2006 Free Software Foundation 3 4 This file is part of GNU Classpath. 5 6 GNU Classpath is free software; you can redistribute it and/or modify 7 it under the terms of the GNU General Public License as published by 8 the Free Software Foundation; either version 2, or (at your option) 9 any later version. 10 11 GNU Classpath is distributed in the hope that it will be useful, but 12 WITHOUT ANY WARRANTY; without even the implied warranty of 13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU 14 General Public License for more details. 15 16 You should have received a copy of the GNU General Public License 17 along with GNU Classpath; see the file COPYING. If not, write to the 18 Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 19 02110-1301 USA. 20 21 Linking this library statically or dynamically with other modules is 22 making a combined work based on this library. Thus, the terms and 23 conditions of the GNU General Public License cover the whole 24 combination. 25 26 As a special exception, the copyright holders of this library give you 27 permission to link this library with independent modules to produce an 28 executable, regardless of the license terms of these independent 29 modules, and to copy and distribute the resulting executable under 30 terms of your choice, provided that you also meet, for each linked 31 terms of your choice, provided that you also meet, for each linked 32 independent module, the terms and conditions of the license of that 33 module. An independent module is a module which is not derived from 34 or based on this library. If you modify this library, you may extend 35 this exception to your version of the library, but you are not 36 obligated to do so. If you do not wish to do so, delete this 37 exception statement from your version. */ 38 39 40 package gnu.classpath.jdwp.id; 41 42 import gnu.classpath.jdwp.JdwpConstants; 43 import gnu.classpath.jdwp.exception.InvalidObjectException; 44 45 import java.io.DataOutputStream; 46 import java.io.IOException; 47 48 /** 49 * This is a base class for all ObjectID-like entities in JDWP, 50 * inculding Objects, ClassObject, ClassLoader, Thread, ThreadGroup, 51 * etc. 52 * 53 * @author Keith Seitz <keiths@redhat.com> 54 */ 55 public class ObjectId 56 extends JdwpId 57 { 58 /** 59 * The object class that this id represents 60 */ 61 public static final Class typeClass = Object.class; 62 63 // Handle to disable garbage collection 64 private Object _handle; 65 66 /** 67 * Constructs a new <code>ObjectId</code> 68 */ ObjectId()69 public ObjectId () 70 { 71 super (JdwpConstants.Tag.OBJECT); 72 } 73 74 /** 75 * Constructs a new <code>ObjectId</code> of the 76 * given type. 77 * 78 * @param tag the tag of this type of object ID 79 */ ObjectId(byte tag)80 public ObjectId (byte tag) 81 { 82 super (tag); 83 } 84 85 /** 86 * Returns the object referred to by this ID 87 * 88 * @returns the object 89 * @throws InvalidObjectException if the object was garbage collected 90 * or is invalid 91 */ getObject()92 public Object getObject () 93 throws InvalidObjectException 94 { 95 Object obj = _reference.get (); 96 if (obj == null) 97 throw new InvalidObjectException (_id); 98 99 return obj; 100 } 101 102 /** 103 * Writes the id to the stream 104 * 105 * @param outStream the stream to which to write 106 * @throws IOException when an error occurs on the <code>OutputStream</code> 107 */ write(DataOutputStream outStream)108 public void write (DataOutputStream outStream) 109 throws IOException 110 { 111 // All we need to do is write out our id as an 8-byte integer 112 outStream.writeLong (_id); 113 } 114 115 /** 116 * Disable garbage collection on object 117 */ disableCollection()118 public void disableCollection () 119 throws InvalidObjectException 120 { 121 _handle = getObject (); 122 } 123 124 /** 125 * Enable garbage collection on object 126 */ enableCollection()127 public void enableCollection () 128 { 129 _handle = null; 130 } 131 } 132