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8187443: Forest Consolidation: Move files to unified layout
Reviewed-by: darcy, ihse
This commit is contained in:
Erik Joelsson
parent
270fe13182
commit
3789983e89
56923 changed files with 3 additions and 15727 deletions
227
src/java.base/share/classes/java/util/Observable.java
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src/java.base/share/classes/java/util/Observable.java
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/*
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* Copyright (c) 1994, 2016, Oracle and/or its affiliates. All rights reserved.
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* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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*
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* This code is free software; you can redistribute it and/or modify it
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* under the terms of the GNU General Public License version 2 only, as
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* published by the Free Software Foundation. Oracle designates this
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* particular file as subject to the "Classpath" exception as provided
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* by Oracle in the LICENSE file that accompanied this code.
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*
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* This code is distributed in the hope that it will be useful, but WITHOUT
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* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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* version 2 for more details (a copy is included in the LICENSE file that
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* accompanied this code).
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*
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* You should have received a copy of the GNU General Public License version
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* 2 along with this work; if not, write to the Free Software Foundation,
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* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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*
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* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
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* or visit www.oracle.com if you need additional information or have any
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* questions.
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*/
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package java.util;
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/**
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* This class represents an observable object, or "data"
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* in the model-view paradigm. It can be subclassed to represent an
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* object that the application wants to have observed.
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* <p>
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* An observable object can have one or more observers. An observer
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* may be any object that implements interface {@code Observer}. After an
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* observable instance changes, an application calling the
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* {@code Observable}'s {@code notifyObservers} method
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* causes all of its observers to be notified of the change by a call
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* to their {@code update} method.
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* <p>
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* The order in which notifications will be delivered is unspecified.
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* The default implementation provided in the Observable class will
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* notify Observers in the order in which they registered interest, but
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* subclasses may change this order, use no guaranteed order, deliver
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* notifications on separate threads, or may guarantee that their
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* subclass follows this order, as they choose.
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* <p>
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* Note that this notification mechanism has nothing to do with threads
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* and is completely separate from the {@code wait} and {@code notify}
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* mechanism of class {@code Object}.
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* <p>
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* When an observable object is newly created, its set of observers is
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* empty. Two observers are considered the same if and only if the
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* {@code equals} method returns true for them.
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*
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* @author Chris Warth
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* @see java.util.Observable#notifyObservers()
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* @see java.util.Observable#notifyObservers(java.lang.Object)
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* @see java.util.Observer
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* @see java.util.Observer#update(java.util.Observable, java.lang.Object)
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* @since 1.0
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*
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* @deprecated
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* This class and the {@link Observer} interface have been deprecated.
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* The event model supported by {@code Observer} and {@code Observable}
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* is quite limited, the order of notifications delivered by
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* {@code Observable} is unspecified, and state changes are not in
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* one-for-one correspondence with notifications.
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* For a richer event model, consider using the
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* {@link java.beans} package. For reliable and ordered
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* messaging among threads, consider using one of the concurrent data
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* structures in the {@link java.util.concurrent} package.
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* For reactive streams style programming, see the
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* {@link java.util.concurrent.Flow} API.
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*/
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@Deprecated(since="9")
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public class Observable {
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private boolean changed = false;
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private Vector<Observer> obs;
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/** Construct an Observable with zero Observers. */
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public Observable() {
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obs = new Vector<>();
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}
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/**
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* Adds an observer to the set of observers for this object, provided
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* that it is not the same as some observer already in the set.
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* The order in which notifications will be delivered to multiple
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* observers is not specified. See the class comment.
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*
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* @param o an observer to be added.
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* @throws NullPointerException if the parameter o is null.
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*/
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public synchronized void addObserver(Observer o) {
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if (o == null)
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throw new NullPointerException();
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if (!obs.contains(o)) {
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obs.addElement(o);
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}
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}
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/**
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* Deletes an observer from the set of observers of this object.
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* Passing {@code null} to this method will have no effect.
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* @param o the observer to be deleted.
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*/
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public synchronized void deleteObserver(Observer o) {
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obs.removeElement(o);
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}
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/**
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* If this object has changed, as indicated by the
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* {@code hasChanged} method, then notify all of its observers
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* and then call the {@code clearChanged} method to
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* indicate that this object has no longer changed.
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* <p>
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* Each observer has its {@code update} method called with two
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* arguments: this observable object and {@code null}. In other
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* words, this method is equivalent to:
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* <blockquote>{@code
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* notifyObservers(null)}</blockquote>
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*
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* @see java.util.Observable#clearChanged()
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* @see java.util.Observable#hasChanged()
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* @see java.util.Observer#update(java.util.Observable, java.lang.Object)
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*/
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public void notifyObservers() {
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notifyObservers(null);
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}
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/**
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* If this object has changed, as indicated by the
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* {@code hasChanged} method, then notify all of its observers
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* and then call the {@code clearChanged} method to indicate
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* that this object has no longer changed.
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* <p>
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* Each observer has its {@code update} method called with two
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* arguments: this observable object and the {@code arg} argument.
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*
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* @param arg any object.
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* @see java.util.Observable#clearChanged()
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* @see java.util.Observable#hasChanged()
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* @see java.util.Observer#update(java.util.Observable, java.lang.Object)
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*/
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public void notifyObservers(Object arg) {
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/*
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* a temporary array buffer, used as a snapshot of the state of
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* current Observers.
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*/
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Object[] arrLocal;
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synchronized (this) {
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/* We don't want the Observer doing callbacks into
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* arbitrary code while holding its own Monitor.
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* The code where we extract each Observable from
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* the Vector and store the state of the Observer
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* needs synchronization, but notifying observers
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* does not (should not). The worst result of any
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* potential race-condition here is that:
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* 1) a newly-added Observer will miss a
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* notification in progress
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* 2) a recently unregistered Observer will be
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* wrongly notified when it doesn't care
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*/
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if (!changed)
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return;
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arrLocal = obs.toArray();
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clearChanged();
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}
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for (int i = arrLocal.length-1; i>=0; i--)
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((Observer)arrLocal[i]).update(this, arg);
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}
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/**
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* Clears the observer list so that this object no longer has any observers.
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*/
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public synchronized void deleteObservers() {
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obs.removeAllElements();
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}
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/**
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* Marks this {@code Observable} object as having been changed; the
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* {@code hasChanged} method will now return {@code true}.
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*/
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protected synchronized void setChanged() {
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changed = true;
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}
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/**
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* Indicates that this object has no longer changed, or that it has
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* already notified all of its observers of its most recent change,
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* so that the {@code hasChanged} method will now return {@code false}.
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* This method is called automatically by the
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* {@code notifyObservers} methods.
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*
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* @see java.util.Observable#notifyObservers()
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* @see java.util.Observable#notifyObservers(java.lang.Object)
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*/
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protected synchronized void clearChanged() {
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changed = false;
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}
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/**
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* Tests if this object has changed.
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*
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* @return {@code true} if and only if the {@code setChanged}
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* method has been called more recently than the
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* {@code clearChanged} method on this object;
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* {@code false} otherwise.
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* @see java.util.Observable#clearChanged()
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* @see java.util.Observable#setChanged()
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*/
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public synchronized boolean hasChanged() {
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return changed;
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}
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/**
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* Returns the number of observers of this {@code Observable} object.
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*
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* @return the number of observers of this object.
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*/
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public synchronized int countObservers() {
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return obs.size();
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}
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}
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