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. 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 8046085 27 * @summary Ensure that when trees are being used for collisions that null key 28 * insertion still works. 29 */ 30 31 import java.util.*; 32 import java.util.stream.IntStream; 33 34 public class PutNullKey { 35 36 // Initial capacity of map 37 // Should be >= the map capacity for treeifying, see HashMap/ConcurrentMap.MIN_TREEIFY_CAPACITY 38 static final int INITIAL_CAPACITY = 64; 39 40 // Maximum size of map 41 // Should be > the treeify threshold, see HashMap/ConcurrentMap.TREEIFY_THRESHOLD 42 static final int SIZE = 256; 43 44 // Load factor of map 45 // A value 1.0 will ensure that a new threshold == capacity 46 static final float LOAD_FACTOR = 1.0f; 47 48 public static class CollidingHash implements Comparable<CollidingHash> { 49 50 private final int value; 51 CollidingHash(int value)52 public CollidingHash(int value) { 53 this.value = value; 54 } 55 56 @Override hashCode()57 public int hashCode() { 58 // intentionally bad hashcode. Force into first bin. 59 return 0; 60 } 61 62 @Override equals(Object o)63 public boolean equals(Object o) { 64 if (null == o) { 65 return false; 66 } 67 68 if (o.getClass() != CollidingHash.class) { 69 return false; 70 } 71 72 return value == ((CollidingHash) o).value; 73 } 74 75 @Override compareTo(CollidingHash o)76 public int compareTo(CollidingHash o) { 77 return value - o.value; 78 } 79 } 80 main(String[] args)81 public static void main(String[] args) throws Exception { 82 Map<Object,Object> m = new HashMap<>(INITIAL_CAPACITY, LOAD_FACTOR); 83 IntStream.range(0, SIZE) 84 .mapToObj(CollidingHash::new) 85 .forEach(e -> { m.put(e, e); }); 86 87 // kaboom? 88 m.put(null, null); 89 } 90 } 91