org.kepler.gui.state

Class StateChangeMonitor

java.lang.Object

org.kepler.gui.state.StateChangeMonitor

public class StateChangeMonitor
extends java.lang.Object

Maintain a registry of objects that are interested in changes in application state. When the application state changes (through posting a notification to this class), distribute the StateChangeEvent to all of the registered listeners. This class follows the singleton pattern because we never need or want more than a single instance to manage all of the change events.

Author:

Matt Jones

Method Summary

Modifier and Type	Method and Description
void	addStateChangeListener(java.lang.String stateChange, StateChangeListener listener) This method is called by objects to register a listener for changes in the application state.
static StateChangeMonitor	getInstance() Get the single instance of the StateChangeMonitor, creating it if needed.
void	notifyStateChange(StateChangeEvent event) Notify the monitor of an application state change so that it in turn can notify all of the registered listeners of that state change.
void	removeStateChangeListener(java.lang.String stateChange, StateChangeListener listener) This method is called by objects to remove a listener for changes in the application state.

Methods inherited from class java.lang.Object

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

Method Detail

getInstance

public static StateChangeMonitor getInstance()

Get the single instance of the StateChangeMonitor, creating it if needed.

Returns:

the single instance of the StateChangeMonitor

addStateChangeListener

public void addStateChangeListener(java.lang.String stateChange,
                                   StateChangeListener listener)

This method is called by objects to register a listener for changes in the application state. Any change in the state will trigger notification.

Parameters:

stateChange - the name of the state change for which notifications should be sent

listener - a reference to the object to be notified of changes

removeStateChangeListener

public void removeStateChangeListener(java.lang.String stateChange,
                                      StateChangeListener listener)

This method is called by objects to remove a listener for changes in the application state. Any change in the state will trigger notification.

Parameters:

stateChange - the name of the state change for which the listener should be removed

listener - a reference to the object to be removed

notifyStateChange

public void notifyStateChange(StateChangeEvent event)

Notify the monitor of an application state change so that it in turn can notify all of the registered listeners of that state change.

Parameters:

event - the StateChangeEvent that has occurred