org.jboss.util.SoftObject Maven / Gradle / Ivy
/*
* JBoss, Home of Professional Open Source
* Copyright 2005, JBoss Inc., and individual contributors as indicated
* by the @authors tag. See the copyright.txt in the distribution for a
* full listing of individual contributors.
*
* This is free software; you can redistribute it and/or modify it
* under the terms of the GNU Lesser General Public License as
* published by the Free Software Foundation; either version 2.1 of
* the License, or (at your option) any later version.
*
* This software 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
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this software; if not, write to the Free
* Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
* 02110-1301 USA, or see the FSF site: http://www.fsf.org.
*/
package org.jboss.util;
import java.lang.ref.SoftReference;
import java.lang.ref.ReferenceQueue;
/**
* Convenience class to wrap an Object into a SoftReference.
*
* Modified from java.util.WeakHashMap.WeakKey.
*
* @version $Revision: 2787 $
* @author Jason Dillon
*/
@SuppressWarnings("unchecked")
public final class SoftObject
extends SoftReference
{
/** The hash code of the nested object */
protected final int hashCode;
/**
* Construct a SoftObject.
*
* @param obj Object to reference.
*/
public SoftObject(final Object obj) {
super(obj);
hashCode = obj.hashCode();
}
/**
* Construct a SoftObject.
*
* @param obj Object to reference.
* @param queue Reference queue.
*/
public SoftObject(final Object obj, final ReferenceQueue queue) {
super(obj, queue);
hashCode = obj.hashCode();
}
/**
* Check the equality of an object with this.
*
* @param obj Object to test equality with.
* @return True if object is equal.
*/
public boolean equals(final Object obj) {
if (obj == this) return true;
if (obj != null && obj.getClass() == getClass()) {
SoftObject soft = (SoftObject)obj;
Object a = this.get();
Object b = soft.get();
if (a == null || b == null) return false;
if (a == b) return true;
return a.equals(b);
}
return false;
}
/**
* Return the hash code of the nested object.
*
* @return The hash code of the nested object.
*/
public int hashCode() {
return hashCode;
}
/////////////////////////////////////////////////////////////////////////
// Factory Methods //
/////////////////////////////////////////////////////////////////////////
/**
* Create a SoftObject for the given object.
*
* @param obj Object to reference.
* @return SoftObject or null if object is null.
*/
public static SoftObject create(final Object obj) {
if (obj == null) return null;
else return new SoftObject(obj);
}
/**
* Create a SoftObject for the given object.
*
* @param obj Object to reference.
* @param queue Reference queue.
* @return SoftObject or null if object is null.
*/
public static SoftObject create(final Object obj,
final ReferenceQueue queue)
{
if (obj == null) return null;
else return new SoftObject(obj, queue);
}
}