1 /* 2 * Copyright (c) 1998, 2011, 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 /* 27 * This source code is provided to illustrate the usage of a given feature 28 * or technique and has been deliberately simplified. Additional steps 29 * required for a production-quality application, such as security checks, 30 * input validation and proper error handling, might not be present in 31 * this sample code. 32 */ 33 34 35 package com.sun.tools.example.debug.bdi; 36 37 import com.sun.jdi.ThreadGroupReference; 38 import java.util.List; 39 import java.util.Stack; 40 import java.util.ArrayList; 41 import java.util.Iterator; 42 43 /** 44 * Descend the tree of thread groups. 45 * @author Robert G. Field 46 */ 47 public class ThreadGroupIterator implements Iterator<ThreadGroupReference> { 48 private final Stack<Iterator<ThreadGroupReference>> stack 49 = new Stack<Iterator<ThreadGroupReference>>(); 50 51 public ThreadGroupIterator(List<ThreadGroupReference> tgl) { 52 push(tgl); 53 } 54 55 public ThreadGroupIterator(ThreadGroupReference tg) { 56 List<ThreadGroupReference> tgl = new ArrayList<ThreadGroupReference>(); 57 tgl.add(tg); 58 push(tgl); 59 } 60 61 /* 62 ThreadGroupIterator() { 63 this(Env.vm().topLevelThreadGroups()); 64 } 65 */ 66 67 private Iterator<ThreadGroupReference> top() { 68 return stack.peek(); 69 } 70 71 /** 72 * The invariant in this class is that the top iterator 73 * on the stack has more elements. If the stack is 74 * empty, there is no top. This method assures 75 * this invariant. 76 */ 77 private void push(List<ThreadGroupReference> tgl) { 78 stack.push(tgl.iterator()); 79 while (!stack.isEmpty() && !top().hasNext()) { 80 stack.pop(); 81 } 82 } 83 84 @Override 85 public boolean hasNext() { 86 return !stack.isEmpty(); 87 } 88 89 @Override 90 public ThreadGroupReference next() { 91 return nextThreadGroup(); 92 } 93 94 public ThreadGroupReference nextThreadGroup() { 95 ThreadGroupReference tg = top().next(); 96 push(tg.threadGroups()); 97 return tg; 98 } 99 100 @Override 101 public void remove() { 102 throw new UnsupportedOperationException(); 103 } 104 105 /* 106 static ThreadGroupReference find(String name) { 107 ThreadGroupIterator tgi = new ThreadGroupIterator(); 108 while (tgi.hasNext()) { 109 ThreadGroupReference tg = tgi.nextThreadGroup(); 110 if (tg.name().equals(name)) { 111 return tg; 112 } 113 } 114 return null; 115 } 116 */ 117 }