org.apache.commons.configuration.event
Class ConfigurationEvent

java.lang.Object
  java.util.EventObject
      org.apache.commons.configuration.event.ConfigurationEvent

All Implemented Interfaces:

Serializable

public class ConfigurationEvent

extends EventObject

An event class for reporting updates on a configuration object.

Event objects of this type are used for "raw" events, i.e. unfiltered modifications of any kind. A level with semantically higher events (e.g. for property changes) may be built on top of this fundamental event mechanism.

Each event can contain the following data:

• A source object, which is usually the configuration object that was modified.
• The event's type. This is a numeric value that corresponds to constant declarations in concrete configuration classes. It describes what exactly has happended.
• If available, the name of the property whose modification caused the event.
• If available, the value of the property that caused this event.
• A flag whether this event was generated before or after the update of the source configuration. A modification of a configuration typically causes two events: one event before and one event after the modification is performed. This allows event listeners to react at the correct point of time.

The following standard events are generated by typical configuration implementations (the constants for the event types are defined in AbstractConfiguration):

EVENT_ADD_PROPERTY

This event is triggered for each call of the addProperty() method of a configuration object. It contains the name of the property, to which new data is added, and the value object that is added to this property (this may be an array or a list if multiple values are added).

EVENT_SET_PROPERTY

Calling the setProperty() method triggers this event. The event object stores the name of the affected property and its new value.

EVENT_CLEAR_PROPERTY

If a property is removed from a configuration (by calling the clearProperty() method), an event of this type is fired. In this case the event object only stores the name of the removed property, the value is null.

EVENT_CLEAR

This event is fired when the whole configuration is cleared. The corresponding event object contains no additional data.

Since:

1.3

Version:

$Id: ConfigurationEvent.java 443105 2006-09-13 20:04:01Z oheger $

Author:

Commons Configuration team

See Also:

Serialized Form

Field Summary

Fields inherited from class java.util.EventObject

source

Constructor Summary

ConfigurationEvent(Object source, int type, String propertyName, Object propertyValue, boolean beforeUpdate)
Creates a new instance of ConfigurationEvent and initializes it.

Method Summary

String	getPropertyName() Returns the name of the affected property.
Object	getPropertyValue() Returns the value of the affected property if available.
int	getType() Returns the type of this event.
boolean	isBeforeUpdate() Returns a flag if this event was generated before or after an update.

Methods inherited from class java.util.EventObject

getSource, toString

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Constructor Detail

ConfigurationEvent

public ConfigurationEvent(Object source,
                          int type,
                          String propertyName,
                          Object propertyValue,
                          boolean beforeUpdate)

Creates a new instance of ConfigurationEvent and initializes it.

Parameters:

source - the event source

type - the event's type

propertyName - the name of the affected property

propertyValue - the value of the affected property

beforeUpdate - the before update flag

Method Detail

getPropertyName

public String getPropertyName()

Returns the name of the affected property. This can be null if no property change has lead to this event.

Returns:

the name of the property

getPropertyValue

public Object getPropertyValue()

Returns the value of the affected property if available.

Returns:

the value of the property; can be null

getType

public int getType()

Returns the type of this event. This describes the update process that caused this event.

Returns:

the event's type

isBeforeUpdate

public boolean isBeforeUpdate()

Returns a flag if this event was generated before or after an update.

Returns:

true if this event was generated before an update; false otherwise