#getValue()/#setValue(Object) methods. Observers can register instances of PropertyChangeListener to be notified if the value changes. If the value is read-only or write-only, an implementor may choose to reject an operation using an UnsupportedOperationException or may do nothing or perform an appropriate action, or may return an appropriate value.
The listeners registered with this ValueModel using #addValueChangeListener will be invoked only with PropertyChangeEvents that have the name set to "value". In other words, the listeners won't get notified when a PropertyChangeEvent is fired that has a null object as the name to indicate an arbitrary set of the event source's properties have changed. This is the case if you use the PropertyChangeSupport, either directly or indirectly, to fire property changes with the property name "value" specified. This constraint ensures that all ValueModel implementors behave like the AbstractValueModel subclasses. In the rare case, where you want to notify a PropertyChangeListener even with PropertyChangeEvents that have no property name set, you can register the listener with #addPropertyChangeListener, not #addValueChangeListener.
AbstractValueModel minimizes the effort required to implement this interface. It uses the PropertyChangeSupport to fire PropertyChangeEvents, and it adds PropertyChangeListeners for the specific property name "value". This ensures that the constraint mentioned above is met.
Implementors are encouraged to provide non-null values for the PropertyChangeEvent's old and new values. However, both may be null. @author Karsten Lentzsch @version $Revision: 1.8 $ @see AbstractValueModel @see ValueHolder @see DisplayProject.binding.beans.PropertyAdapter Copyright (c) 2002-2005 JGoodies Karsten Lentzsch. All rights reserved. Redistribution and use in source and binary forms, with or without modification, are permitted provided that the following conditions are met: o Redistributions of source code must retain the above copyright notice, this list of conditions and the following disclaimer. o Redistributions in binary form must reproduce the above copyright notice, this list of conditions and the following disclaimer in the documentation and/or other materials provided with the distribution. o Neither the name of JGoodies Karsten Lentzsch nor the names of its contributors may be used to endorse or promote products derived from this software without specific prior written permission. THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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