1 /* 2 * Copyright (c) 2014, Oracle and/or its affiliates. All rights reserved. 3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. 4 * 5 * This code is free software; you can redistribute it and/or modify it 6 * under the terms of the GNU General Public License version 2 only, as 7 * published by the Free Software Foundation. Oracle designates this 8 * particular file as subject to the "Classpath" exception as provided 9 * by Oracle in the LICENSE file that accompanied this code. 10 * 11 * This code is distributed in the hope that it will be useful, but WITHOUT 12 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 13 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 14 * version 2 for more details (a copy is included in the LICENSE file that 15 * accompanied this code). 16 * 17 * You should have received a copy of the GNU General Public License version 18 * 2 along with this work; if not, write to the Free Software Foundation, 19 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. 20 * 21 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA 22 * or visit www.oracle.com if you need additional information or have any 23 * questions. 24 */ 25 26 package sun.awt.util; 27 28 /** 29 * A utility class needed to access the root {@code ThreadGroup} 30 * 31 * The class should not depend on any others, because it' called from JNI_OnLoad of the AWT 32 * native library. Triggering class loading could lead to a deadlock. 33 */ 34 public final class ThreadGroupUtils { 35 ThreadGroupUtils()36 private ThreadGroupUtils() { 37 // Avoid instantiation 38 } 39 40 /** 41 * Returns a root thread group. 42 * Should be called with {@link sun.security.util.SecurityConstants#MODIFY_THREADGROUP_PERMISSION} 43 * 44 * @return a root {@code ThreadGroup} 45 */ getRootThreadGroup()46 public static ThreadGroup getRootThreadGroup() { 47 ThreadGroup currentTG = Thread.currentThread().getThreadGroup(); 48 ThreadGroup parentTG = currentTG.getParent(); 49 while (parentTG != null) { 50 currentTG = parentTG; 51 parentTG = currentTG.getParent(); 52 } 53 return currentTG; 54 } 55 } 56