ca.odell.glazedlists.calculation.Calculation Maven / Gradle / Ivy
/* Glazed Lists (c) 2003-2007 */
/* http://publicobject.com/glazedlists/ publicobject.com,*/
/* O'Dell Engineering Ltd.*/
package ca.odell.glazedlists.calculation;
import java.beans.PropertyChangeListener;
/**
* It is sometimes desirable to compute single values from an entire List of
* objects. For example, an EventList may represent the ages of all
* customers and it is useful to display the average age of all customers. The
* average can be modeled as a Calculation which is updated as the
* contents of the EventList change and in turn broadcast PropertyChangeEvents
* to registered listeners describing a change in the calculated value.
*
* In this way, Calculation object represent a continuation of data
* transformation from the domain of Lists to the domain of simple Number
* objects calculated from the elements of those Lists.
*
* @author James Lemieux
*/
public interface Calculation {
/**
* @param pcl a PropertyChangeListener to notify any time the
* {@link #getValue value} changes
*/
public void addPropertyChangeListener(PropertyChangeListener pcl);
/**
* @param pcl a PropertyChangeListener which should no longer be notified
* of {@link #getValue value} changes
*/
public void removePropertyChangeListener(PropertyChangeListener pcl);
/**
* @return a human readable name for this Calculation
*/
public String getName();
/**
* Adjusts the Calculation to have the new name;
*
* @param name the new human-readable name of this Calculation
*/
public void setName(String name);
/**
* @return the latest calculated value
*/
public N getValue();
/**
* Cease the updating of this Calculation from its data sources and free
* them for garbage collection.
*/
public void dispose();
}