org.jscience.util
Interface ChangeListener

All Superinterfaces:

java.util.EventListener

All Known Implementing Classes:

ChangeAdapter, ChangeForwarder, ChangeForwarder.Retyper, ChangeListener.AlwaysVetoListener, ChangeListener.LoggingListener

public interface ChangeListener
extends java.util.EventListener

Interface for objects which listen to ChangeEvents.

Since:

1.1

Nested Class Summary

static class	ChangeListener.AlwaysVetoListener An implementation that always vetoes everything.
static class	ChangeListener.LoggingListener A listener that writes information about the event stream to a PrintStream.

Field Summary

static ChangeListener	ALWAYS_VETO Convenience implementation which vetoes every change of which it is notified.
static ChangeListener	LOG_TO_OUT Convenience implementation that echoes all events to out.

Method Summary

void	postChange(ChangeEvent cev) Called when a change has just taken place.
void	preChange(ChangeEvent cev) Called before a change takes place.

Field Detail

ALWAYS_VETO

static final ChangeListener ALWAYS_VETO

Convenience implementation which vetoes every change of which it is notified. You could add this to an object directly to stop it changing in any way, or alternatively you could add it for a specific ChangeType to stop that single item from altering.

LOG_TO_OUT

static final ChangeListener LOG_TO_OUT

Convenience implementation that echoes all events to out.

Method Detail

preChange

void preChange(ChangeEvent cev)
               throws ChangeVetoException

Called before a change takes place.

This is your chance to stop the change by throwing a ChangeVetoException. This method does not indicate that the change will definitely take place, so it is not recomended that you take any positive action within this handler.

Parameters:

cev - An event encapsulating the change which is about to take place.

Throws:

ChangeVetoException - Description of Exception

ChangeVetoException - if the receiver does not wish this change to occur at this time.

postChange

void postChange(ChangeEvent cev)

Called when a change has just taken place.

This method is the place to perform any behavior in response to the change event.

Parameters:

cev - An event encapsulating the change which has occured.