1/* 2 * Copyright (c) 2001, 2005, 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. 8 * 9 * This code is distributed in the hope that it will be useful, but WITHOUT 10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 12 * version 2 for more details (a copy is included in the LICENSE file that 13 * accompanied this code). 14 * 15 * You should have received a copy of the GNU General Public License version 16 * 2 along with this work; if not, write to the Free Software Foundation, 17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. 18 * 19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA 20 * or visit www.oracle.com if you need additional information or have any 21 * questions. 22 */ 23 24/** 25 * @test 26 * @bug 4421469 6282555 27 * @summary Hashtable's toString method should detect self-referential 28 * hash tables rather than throwing a StackOverflowException. 29 * @author Josh Bloch, Martin Buchholz 30 */ 31 32import java.util.*; 33import java.util.concurrent.*; 34 35public class SelfRef { 36 public static void main(String[] args) { 37 testMap(new Hashtable<Object,Object>()); 38 testMap(new HashMap<Object,Object>()); 39 testMap(new LinkedHashMap<Object,Object>()); 40 testMap(new ConcurrentHashMap<Object,Object>()); 41 } 42 43 private static void testMap(Map<Object,Object> m) { 44 if (! (m.toString().equals("{}"))) 45 throw new Error(); 46 m.put("Harvey", m); 47 if (! (m.toString().equals("{Harvey=(this Map)}"))) 48 throw new Error(); 49 m.clear(); 50 m.put(m, "Harvey"); 51 if (! (m.toString().equals("{(this Map)=Harvey}"))) 52 throw new Error(); 53 m.clear(); 54 m.hashCode(); 55 } 56} 57