| /******************************************************************************* |
| * 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; |
| } |
| } |