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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.


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).


Null values may be provided for the old and the new values if their
true values are not known.


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.

Since:1.1
/**
 * 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.
 *
 * @since 1.1
 */
public class PropertyChangeEvent extends EventObject {
    private static final long serialVersionUID = 7042693688939648123L;

    
Constructs a new PropertyChangeEvent. 
Params:
  • source –        the bean that fired the event
  • propertyName –  the programmatic name of the property that was changed
  • oldValue –      the old value of the property
  • newValue –      the new value of the property
Throws:
/**
     * 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.

Returns: The programmatic name of the property that was changed.
         May be null if multiple properties have changed.
/**
     * 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.

Returns: The new value for the property, expressed as an Object.
         May be null if multiple properties have changed.
/**
     * 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.

Returns: The old value for the property, expressed as an Object.
         May be null if multiple properties have changed.
/**
     * 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.

Params:
  • propagationId –  The propagationId object for the event.
/**
     * 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.

Returns:the propagationId object associated with a bound/constrained
         property update.
/**
     * 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
/**
     * 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
/**
     * 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
/**
     * Previous value for property.  May be null if not known.
     * @serial
     */
    private Object oldValue;

    
Propagation ID.  May be null.

See Also:
@serial
/**
     * Propagation ID.  May be null.
     * @serial
     * @see #getPropagationId
     */
    private Object propagationId;

    
Returns a string representation of the object.

Returns:a string representation of the object
Since:1.7
/**
     * 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) {
    }
}