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The message box acts as a buffer for incoming messages. Its major property is to be usable from any thread. This allows any external source to post any message at any time without having to wonder about synchronisation.

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package org.miv.mbox;

import java.util.ArrayList;

/**
 * Implementation of a message box to be used without having to inherit it.
 * 
 * 
 * This message box is a fully fledged box that can work by itself, receive
 * messages and dispatch them to a listener when invoked. It is the pending of
 * the {@link org.miv.mbox.MBoxBase} when it is not possible to inherit from it.
 * 
 *
 * @author Antoine Dutot
 * @since  28102006
 */
public class MBoxStandalone extends MBoxBase
{
// Attributes

	/**
	 * Listener for this message box. There can be only one listener per message
	 * box.
	 */
	protected ArrayList listeners = new ArrayList();

	/**
	 * Notify every threads waiting on this mbox monitor at each post?.
	 */
	protected boolean notifyOnPost = false;
	
// Constructors

	/**
	 * New empty message box dispatching messages to a given listener.
	 * @param listener The message reader.
	 */
	public MBoxStandalone( MBoxListener listener )
	{
		listeners.add( listener );
	}
	
	/**
	 * New empty message box. To use this, you must add a listener.
	 */
	public MBoxStandalone()
	{
	}

// Access

	/**
	 * Does the {@link #post(String,Object...)} method must notify any
	 * thread waiting on the monitor of this message box?.
	 */
	public boolean notifyOnPost()
	{
		return notifyOnPost;
	}

// Command

	/**
	 * Specify if each call to {@link #post(String, Object...)} should notify threads
	 * waiting on the monitor of this message box.
	 */
	public void setNotifyOnPost( boolean on )
	{
		notifyOnPost = on;
	}
	
	@Override
	public synchronized void post( String from, Object ... data )
	{
		super.post( from, data );
		
		if( notifyOnPost )
			notifyAll();
	}
	
	@Override
	public void processMessage( String from, Object data[] )
	{
		for( MBoxListener listener: listeners )
			listener.processMessage( from, data );
	}
	
	/**
	 * Set the listener of this message box. All messages will be sent to it
	 * when {@link #processMessages()} will be called.
	 * @param listener The message listener.
	 */
	@Deprecated
	public void setListener( MBoxListener listener )
	{
		listeners.add( listener );
	}
	
	/**
	 * Add a listener for this message box. All message will be sent to it
	 * when {@link #processMessages()} is called. Note that all listeners
	 * receive all messages. That is if there is N listeners, and the box
	 * received one message, the message is sent N times, once for each
	 * listener.
	 * @param listener The listener to add.
	 */
	public void addListener( MBoxListener listener )
	{
		listeners.add( listener );
	}

	/**
	 * Remove a listener.
	 * @param listener The listener to remove.
	 */
	public void removeListener( MBoxListener listener )
	{
		int index = listeners.indexOf( listener );
	
		if( index >= 0 )
			listeners.remove( index );
	}
}