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/*
* This file is part of the LibreOffice project.
*
* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at http://mozilla.org/MPL/2.0/.
*
* This file incorporates work covered by the following license notice:
*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed
* with this work for additional information regarding copyright
* ownership. The ASF licenses this file to you under the Apache
* License, Version 2.0 (the "License"); you may not use this file
* except in compliance with the License. You may obtain a copy of
* the License at http://www.apache.org/licenses/LICENSE-2.0 .
*/
package com.sun.star.lib.uno.helper;
import java.lang.ref.WeakReference;
import com.sun.star.uno.XAdapter;
import com.sun.star.uno.XReference;
import java.util.List;
import java.util.Collections;
import java.util.LinkedList;
/** An XAdapter implementation that holds a weak reference (java.lang.ref.WeakReference)
* to an object. Clients can register listener (com.sun.star.lang.XReference) which
* are notified when the the object (the one which is kept weak) is being finalized. That
* is, that object is being destroyed because there are not any hard references
* to it.
*/
public class WeakAdapter implements XAdapter
{
private final boolean DEBUG= false;
// references the XWeak implementation
private WeakReference<Object> m_weakRef;
// contains XReference objects registered by addReference
private List<XReference> m_xreferenceList;
/**
*@param component the object that is to be held weak
*/
public WeakAdapter(Object component)
{
m_weakRef= new WeakReference<Object>(component);
m_xreferenceList= Collections.synchronizedList( new LinkedList<XReference>());
}
/** Called by the XWeak implementation (WeakBase) when it is being finalized.
* It is only being called once.
* The registererd XReference listeners are notified. On notification they are
* to unregister themselves. The notification is thread-safe. However, it is possible
* to add a listener during the notification process, which will never receive a
* notification. To prevent this, one would have to synchronize this method with
* the addReference method. But this can result in deadlocks in a multithreaded
* environment.
*/
void referentDying()
{
//synchronized call
XReference[] references= m_xreferenceList.toArray(new XReference[m_xreferenceList.size()]);
for (int i= references.length; i > 0; i--)
{
references[i-1].dispose();
}
}
/** Method of com.sun.star.uno.XAdapter. It is called to obtain a hard reference
* to the object which is kept weak by this instance.
* @return hard reference to the object
*/
public Object queryAdapted()
{
return m_weakRef.get();
}
/** Method of com.sun.star.uno.XAdapter. Called by clients to register listener which
* are notified when the weak object is dying.
*@param xReference a listener
*/
public void removeReference(XReference xReference)
{
m_xreferenceList.remove(xReference);
}
/** Method of com.sun.star.uno.XAdapter. Called by clients to unregister listeners.
*@param a listener
*/
public void addReference(XReference xReference)
{
m_xreferenceList.add(xReference);
}
}
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