/*
 *   
 *
 * Copyright  1990-2007 Sun Microsystems, Inc. All Rights Reserved.
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER
 * 
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License version
 * 2 only, as published by the Free Software Foundation.
 * 
 * This program is distributed in the hope that it will be useful, but
 * WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
 * General Public License version 2 for more details (a copy is
 * included at /legal/license.txt).
 * 
 * You should have received a copy of the GNU General Public License
 * version 2 along with this work; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
 * 02110-1301 USA
 * 
 * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa
 * Clara, CA 95054 or visit www.sun.com if you need additional
 * information or have any questions.
 */

package javax.microedition.lcdui;

/**  
 * This interface is used by applications which need to receive
 * high-level events from the implementation. An application will
 * provide an implementation of a <code>CommandListener</code>
 * (typically by using
 * a nested class or an inner class) and will then provide the
 * instance to the <CODE>addCommand</CODE> method on a
 * <code>Displayable</code> in
 * order to receive high-level events on that screen.
 *
 * <p>The specification does not require the platform to create several 
 * threads for the event delivery.
 * Thus, if a <code>CommandListener</code> method does not return
 * or the return is
 * not delayed, the system may be blocked. So, there is the following note to
 * application developers:</p>
 * <UL>
 * <LI><em>the <code>CommandListener</code> method should return
 * immediately</em>.</LI>
 * </UL>
 *
 * @see javax.microedition.lcdui.Displayable#setCommandListener
 * @since MIDP 1.0 
 */
public interface CommandListener {
    
    /**
     * Indicates that a command event has occurred on
     * <code>Displayable d</code>.
     *
     * @param c a <code>Command</code> object identifying the
     * command. This is either one of the
     * applications have been added to <code>Displayable</code> with 
     * {@link Displayable#addCommand(Command)
     * addCommand(Command)} or is the implicit 
     * {@link List#SELECT_COMMAND SELECT_COMMAND} of
     * <code>List</code>.
     * @param d the <code>Displayable</code> on which this event
     *  has occurred
     */
    void commandAction(Command c, Displayable d);
}