1/* 2 * Copyright (c) 2012, 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 7173432 27 * @summary If the key to be inserted into a HashMap is null and the table 28 * needs to be resized as part of the insertion then addEntry will try to 29 * recalculate the hash of a null key. This will fail with an NPE. 30 */ 31 32import java.util.*; 33 34public class NullKeyAtResize { 35 public static void main(String[] args) throws Exception { 36 List<Object> old_order = new ArrayList<>(); 37 Map<Object,Object> m = new HashMap<>(16); 38 int number = 0; 39 while(number < 100000) { 40 m.put(null,null); // try to put in null. This may cause resize. 41 m.remove(null); // remove it. 42 Integer adding = (number += 100); 43 m.put(adding, null); // try to put in a number. This wont cause resize. 44 List<Object> new_order = new ArrayList<>(); 45 new_order.addAll(m.keySet()); 46 new_order.remove(adding); 47 if(!old_order.equals(new_order)) { 48 // we resized and didn't crash. 49 System.out.println("Encountered resize after " + (number / 100) + " iterations"); 50 break; 51 } 52 // remember this order for the next time around. 53 old_order.clear(); 54 old_order.addAll(m.keySet()); 55 } 56 if(number == 100000) { 57 throw new Error("Resize never occurred"); 58 } 59 } 60} 61