observablelist.java

本程序是有IBM开发的一个基于数据表格的组件,里面有相关的例子和DOC,本站资料仅为大家学习之用

package com.ibm.j2x.util.collection;

import java.util.ArrayList;
import java.util.Collection;
import java.util.Iterator;
import java.util.List;
import java.util.ListIterator;

import com.ibm.j2x.event.CollectionEvent;
import com.ibm.j2x.event.CollectionListener;

/**
 * The ObservableList subclasses the ArrayList and 
 * overrides all the functions that change the internally
 * stored collection.  In the overridden function, it simply
 * calls the super class's function and fires a
 * CollectionEvent to let observers know the collection
 * has changed.
 * @author MAbernethy
 *
 */
public class ObservableList extends ArrayList implements ObservableCollection
{	
	/** the observers of this collection */
	protected ArrayList listeners = new ArrayList();
	
	/**
	 * Constructs an empty list with the specified initial capacity.
	 * @param initialCapacity  the initial capacity of the list
	 */
	public ObservableList(int initialCapacity) 
	{
		super(initialCapacity);
	}

	/**
	 * Constructs an empty list with an initial capacity of ten.
	 *
	 */
	 public ObservableList() 
	 {
	 	this(10);
	 }
	
	/**
	 * Constructs a list containing the elements of the specified collection, 
	 * in the order they are returned by the collection's iterator.
	 * @param c the collection whose elements are to be placed into this list.
	 */
	 public ObservableList(Collection c) 
	 {
		super(c);
		fireCollectionEvent(new CollectionEvent(this, CollectionEvent.ADD));
	 }	
	
	/**
	 * Calls the super class's corresponding method
	 * and fires a CollectionEvent. 
	 */
	public boolean add(Object o)
	{
		boolean b = super.add(o);
		fireCollectionEvent(new CollectionEvent(this, CollectionEvent.ADD));
		return b;
	}

	/**
	 * Calls the super class's corresponding method
	 * and fires a CollectionEvent. 
	 */
	public boolean remove(Object o)
	{
		boolean b = super.remove(o);
		fireCollectionEvent(new CollectionEvent(this, CollectionEvent.REMOVE));
		return b;
	}

	/**
	 * Calls the super class's corresponding method
	 * and fires a CollectionEvent. 
	 */
	public boolean addAll(Collection c)
	{
		boolean b = super.addAll(c);
		fireCollectionEvent(new CollectionEvent(this, CollectionEvent.ADD));
		return b;		
	}

	/**
	 * Calls the super class's corresponding method
	 * and fires a CollectionEvent. 
	 */
	public boolean addAll(int index, Collection c)
	{
		boolean b = super.addAll(index, c);
		fireCollectionEvent(new CollectionEvent(this, CollectionEvent.ADD));
		return b;
	}

	/**
	 * Calls the super class's corresponding method
	 * and fires a CollectionEvent. 
	 */
	public boolean removeAll(Collection c)
	{
		boolean b = super.removeAll(c);
		fireCollectionEvent(new CollectionEvent(this, CollectionEvent.REMOVE));
		return b;
	}

	/**
	 * Calls the super class's corresponding method
	 * and fires a CollectionEvent. 
	 */
	public void clear()
	{
		super.clear();
		fireCollectionEvent(new CollectionEvent(this, CollectionEvent.REMOVE));
	}

	/**
	 * Calls the super class's corresponding method
	 * and fires a CollectionEvent. 
	 */
	public Object set(int index, Object element)
	{
		Object o = super.set(index, element);
		fireCollectionEvent(new CollectionEvent(this, CollectionEvent.MODIFY));
		return o;
	}

	/**
	 * Calls the super class's corresponding method
	 * and fires a CollectionEvent. 
	 */
	public void add(int index, Object element)
	{
		super.add(index, element);
		fireCollectionEvent(new CollectionEvent(this, CollectionEvent.ADD));	
	}

	/**
	 * Calls the super class's corresponding method
	 * and fires a CollectionEvent. 
	 */
	public Object remove(int index)
	{
		Object o = super.remove(index);
		fireCollectionEvent(new CollectionEvent(this, CollectionEvent.REMOVE));
		return o;
	}
	
	/**
	 * Calls the super class's corresponding method
	 * and fires a CollectionEvent. 
	 */
	public boolean retainAll(Collection c)
	{
		boolean b = super.retainAll(c);
		fireCollectionEvent(new CollectionEvent(this, CollectionEvent.REMOVE));
		return b;
	}
	
	/**
	 * Adds a listener to this collection.
	 * @param l the CollectionListener
	 */
	public void addCollectionListener(CollectionListener l)
	{
		if ( ! listeners.contains(l))
			listeners.add(l);
	}

	/**
	 * Removes the listener from this collection.
	 * @param l the CollectionListener
	 */
	public void removeCollectionListener(CollectionListener l)
	{
		listeners.remove(l);
	}
	
	/**
	 * Fires a CollectionEvent to all listeners.
	 * @param e the CollectionEvent
	 */
	protected void fireCollectionEvent(CollectionEvent e)
	{
		for (Iterator i=listeners.iterator(); i.hasNext();)
			((CollectionListener)i.next()).collectionChanged(e);
	}

}