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/*******************************************************************************
* Copyright (c) 2010 Oracle. All rights reserved.
* This program and the accompanying materials are made available under the
* terms of the Eclipse Public License v1.0, which accompanies this distribution
* and is available at http://www.eclipse.org/legal/epl-v10.html.
*
* Contributors:
* Oracle - initial API and implementation
******************************************************************************/
package org.eclipse.jpt.common.utility.internal;
/**
* Provide a container for passing an object that can be changed by the
* recipient. If the value is set at any time after construction of the
* reference, the reference is marked "set". This allows the client to
* detect whether the server/recipient ever set the value, even if it remains
* unchanged. This is particularly useful when the value can be set to
* <code>null</code>.
* <p>
* The reference can be set multiple times, but it can
* never be "unset" once it is "set".
*/
public class FlaggedObjectReference<V>
extends SimpleObjectReference<V>
{
private volatile boolean set = false;
private static final long serialVersionUID = 1L;
// ********** constructors **********
/**
* Create an object reference with the specified initial value.
*/
public FlaggedObjectReference(V value) {
super(value);
}
/**
* Create an object reference with an initial value of
* <code>null</code>.
*/
public FlaggedObjectReference() {
super();
}
// ********** set **********
public boolean isSet() {
return this.set;
}
// ********** overrides **********
@Override
public V setValue(V value) {
this.set = true;
return super.setValue(value);
}
@Override
public String toString() {
String s = super.toString();
return (this.set) ? '*' + s : s;
}
}
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