package com.onaro.util.jfc.grouping;

import java.util.EventListener;

import com.onaro.util.ListenerList;

/**
 * Allows user to trace sorting changes.
 */
public interface SortingListener extends EventListener {

    /**
     * When sorting changes, tells the new sorting column and order.
     * @param column the number of the sorting column
     * @param ascending true if the sorting is ascending
     */
    public void sortingChanged(int column, boolean ascending);

    /**
     * Register an event firer with the <code>ListenerList</code> utility for this listener.
     */
    final static FireEvent firer = new FireEvent();
}

/**
 * Used for sending event to {@link SortingListener}s by the
 * {@link ListenerList} utility.
 */
class FireEvent implements ListenerList.FireEvent<SortingListener,SortingChangedEvent> {

    FireEvent() {
        ListenerList.addFireEvent(SortingListener.class, this);
    }

    public void fire(SortingListener listener, SortingChangedEvent event) {
        listener.sortingChanged(event.getColumn(), event.isAscending());
    }
}