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Diffstat (limited to 'libjava/java/lang/ref/PhantomReference.java')
-rw-r--r-- | libjava/java/lang/ref/PhantomReference.java | 62 |
1 files changed, 62 insertions, 0 deletions
diff --git a/libjava/java/lang/ref/PhantomReference.java b/libjava/java/lang/ref/PhantomReference.java new file mode 100644 index 00000000000..7c07b52eccb --- /dev/null +++ b/libjava/java/lang/ref/PhantomReference.java @@ -0,0 +1,62 @@ +/* java.lang.ref.PhantomReference + Copyright (C) 1999 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., 59 Temple Place, Suite 330, Boston, MA +02111-1307 USA. + +As a special exception, if you link this library with other files to +produce an executable, this library does not by itself cause the +resulting executable to be covered by the GNU General Public License. +This exception does not however invalidate any other reasons why the +executable file might be covered by the GNU General Public License. */ + + +package java.lang.ref; + +/** + * A phantom reference is useful, to get notified, when an object got + * finalized. You can't access that object though, since it is + * finalized. This is the reason, why <code>get()</code> always + * returns null. + * + * @author Jochen Hoenicke + */ +public class PhantomReference + extends Reference +{ + /** + * Creates a new phantom reference. + * @param referent the object that should be watched. + * @param q the queue that should be notified, if the referent was + * finalized. This mustn't be <code>null</code>. + * @exception NullPointerException if q is null. + */ + public PhantomReference(Object referent, ReferenceQueue q) + { + super(referent, q); + } + + /** + * Returns the object, this reference refers to. + * @return <code>null</code>, since the refered object may be + * finalized and thus not accessible. + */ + public Object get() + { + return null; + } +} |