如果在Mac上运行，此方法将设置系统属性，该属性告诉菜单栏显示在屏幕顶部。

/*

 * Copyright (c) 2013, Jeremy Brooks

 * All rights reserved.

 *

 * Redistribution and use in source and binary forms, with or without modification, are permitted provided that the following conditions are met:

 *

 * Redistributions of source code must retain the above copyright notice, this list of conditions and the following disclaimer.

 * Redistributions in binary form must reproduce the above copyright notice, this list of conditions and the following

 * disclaimer in the documentation and/or other materials provided with the distribution.

 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES,

 * INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE

 * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,

 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;

 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,

 * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF

 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

 */
//from 时   代    Java - nowjava.com

public class Main{

    /**

     * If running on a Mac, this method will set the

     * system property which tells the menu bar to

     * display at the top of the screen.

     */

    public static void setMacMenuBar() {

        // SET SYSTEM PROPERTY FOR MAC-STYLE MENU BAR

        if (isRunningOnMac()) {

            System.setProperty("apple.laf.useScreenMenuBar", "true");

        }

    }