/*

 * Copyright (c) 1996, 2011, Oracle and/or its affiliates. All rights reserved.

 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

 *

 * This code is free software; you can redistribute it and/or modify it

 * under the terms of the GNU General Public License version 2 only, as

 * published by the Free Software Foundation.  Oracle designates this

 * particular file as subject to the "Classpath" exception as provided

 * by Oracle in the LICENSE file that accompanied this code.

 *

 * This code is distributed in the hope that it will be useful, but WITHOUT

 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

 * version 2 for more details (a copy is included in the LICENSE file that

 * accompanied this code).

 *

 * You should have received a copy of the GNU General Public License version

 * 2 along with this work; if not, write to the Free Software Foundation,

 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

 *

 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

 * or visit www.oracle.com if you need additional information or have any

 * questions.

 */

package java.beans;

import java.util.EventObject;

/**

 * A "PropertyChange" event gets delivered whenever a bean changes a "bound"

 * or "constrained" property.  A PropertyChangeEvent object is sent as an

 * argument to the PropertyChangeListener and VetoableChangeListener methods.

 * <P>

 * Normally PropertyChangeEvents are accompanied by the name and the old

 * and new value of the changed property.  If the new value is a primitive

 * type (such as int or boolean) it must be wrapped as the

 * corresponding java.lang.* Object type (such as Integer or Boolean).

 * <P>

 * Null values may be provided for the old and the new values if their

 * true values are not known.

 * <P>

 * An event source may send a null object as the name to indicate that an

 * arbitrary set of if its properties have changed.  In this case the

 * old and new values should also be null.

 */

public class PropertyChangeEvent extends EventObject {

    private static final long serialVersionUID = 7042693688939648123L;

    /**

     * Constructs a new {@code PropertyChangeEvent}.

     *

     * @param source        the bean that fired the event

     * @param propertyName  the programmatic name of the property that was changed

     * @param oldValue      the old value of the property

     * @param newValue      the new value of the property

     *

     * @throws IllegalArgumentException if {@code source} is {@code null}

     */

    public PropertyChangeEvent(Object source, String propertyName,

                               Object oldValue, Object newValue) {

        super(source);

        this.propertyName = propertyName;

        this.newValue = newValue;

        this.oldValue = oldValue;

    }

    /**

     * Gets the programmatic name of the property that was changed.

     *

     * @return  The programmatic name of the property that was changed.

     *          May be null if multiple properties have changed.

     */

    public String getPropertyName() {

        return propertyName;

    }

    /**

     * Gets the new value for the property, expressed as an Object.

     *

     * @return  The new value for the property, expressed as an Object.

     *          May be null if multiple properties have changed.

     */

    public Object getNewValue() {

        return newValue;

    }

    /**

     * Gets the old value for the property, expressed as an Object.

     *

     * @return  The old value for the property, expressed as an Object.

     *          May be null if multiple properties have changed.

     */

    public Object getOldValue() {

        return oldValue;

    }

    /**

     * Sets the propagationId object for the event.

     *

     * @param propagationId  The propagationId object for the event.

     */

    public void setPropagationId(Object propagationId) {

        this.propagationId = propagationId;

    }

    /**

     * The "propagationId" field is reserved for future use.  In Beans 1.0

     * the sole requirement is that if a listener catches a PropertyChangeEvent

     * and then fires a PropertyChangeEvent of its own, then it should

     * make sure that it propagates the propagationId field from its

     * incoming event to its outgoing event.

     *

     * @return the propagationId object associated with a bound/constrained

     *          property update.

     */

    public Object getPropagationId() {

        return propagationId;

    }

    /**

     * name of the property that changed.  May be null, if not known.

     * @serial

     */

    private String propertyName;

    /**

     * New value for property.  May be null if not known.

     * @serial

     */

    private Object newValue;

    /**

     * Previous value for property.  May be null if not known.

     * @serial

     */

    private Object oldValue;

    /**

     * Propagation ID.  May be null.

     * @serial

     * @see #getPropagationId

     */

    private Object propagationId;

    /**

     * Returns a string representation of the object.

     *

     * @return a string representation of the object

     *

     * @since 1.7

     */

    public String toString() {

        StringBuilder sb = new StringBuilder(getClass().getName());

        sb.append("[propertyName=").append(getPropertyName());

        appendTo(sb);

        sb.append("; oldValue=").append(getOldValue());

        sb.append("; newValue=").append(getNewValue());

        sb.append("; propagationId=").append(getPropagationId());

        sb.append("; source=").append(getSource());

        return sb.append("]").toString();

    }

    void appendTo(StringBuilder sb) {

    }

}