Here you can find the source of rootFrame(@Nonnull Component component)
@Nullable public static JFrame rootFrame(@Nonnull Component component)
//package com.java2s; /**/*from ww w . ja v a2 s. c o m*/ * Copyright (C) cedarsoft GmbH. * * Licensed under the GNU General Public License version 3 (the "License") * with Classpath Exception; you may not use this file except in compliance * with the License. You may obtain a copy of the License at * * http://www.cedarsoft.org/gpl3ce * (GPL 3 with Classpath Exception) * * This code is free software; you can redistribute it and/or modify it * under the terms of the GNU General Public License version 3 only, as * published by the Free Software Foundation. cedarsoft GmbH designates this * particular file as subject to the "Classpath" exception as provided * by cedarsoft GmbH in the LICENSE file that accompanied this code. * * This code 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 3 for more details (a copy is included in the LICENSE file that * accompanied this code). * * You should have received a copy of the GNU General Public License version * 3 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 cedarsoft GmbH, 72810 Gomaringen, Germany, * or visit www.cedarsoft.com if you need additional information or * have any questions. */ import javax.annotation.Nonnull; import javax.annotation.Nullable; import javax.swing.JFrame; import javax.swing.SwingUtilities; import java.awt.Component; import java.awt.Window; public class Main { @Nullable public static JFrame rootFrame(@Nonnull Component component) { Window window = SwingUtilities.getWindowAncestor(component); if (window instanceof JFrame) { return (JFrame) window; } return null; } }