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7173432: Handle null key at HashMap resize

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If the key to be inserted into a HashMap is null and the table needs to be resized as part of the insertion then addEntry will try to recalculate the hash of a null key. This will fail with an NPE.

Reviewed-by: darcy
This commit is contained in:
Mike Duigou 2012-06-01 00:05:21 -07:00
parent 7dfc5df74e
commit 59ccdc0fbc
2 changed files with 61 additions and 1 deletions
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2
jdk/src/share/classes/java/util/HashMap.java
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@ -784,7 +784,7 @@ public class HashMap<K,V>
void addEntry(int hash, K key, V value, int bucketIndex) {
if ((size >= threshold) && (null != table[bucketIndex])) {
resize(2 * table.length);
hash = hash(key);
hash = (null != key) ? hash(key) : 0;
bucketIndex = indexFor(hash, table.length);
}

60
jdk/test/java/util/HashMap/NullKeyAtResize.java Normal file
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@ -0,0 +1,60 @@
/*
* Copyright (c) 2012, Oracle and/or its affiliates. All rights reserved.
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* This code is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License version 2 only, as
* published by the Free Software Foundation.
*
* This code is distributed in the hope that it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
* version 2 for more details (a copy is included in the LICENSE file that
* accompanied this code).
*
* You should have received a copy of the GNU General Public License version
* 2 along with this work; if not, write to the Free Software Foundation,
* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
*
* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
* or visit www.oracle.com if you need additional information or have any
* questions.
*/
/**
* @test
* @bug 7173432
* @summary If the key to be inserted into a HashMap is null and the table
* needs to be resized as part of the insertion then addEntry will try to
* recalculate the hash of a null key. This will fail with an NPE.
*/
import java.util.*;
public class NullKeyAtResize {
public static void main(String[] args) throws Exception {
List<Object> old_order = new ArrayList<>();
Map<Object,Object> m = new HashMap<>(16);
int number = 0;
while(number < 100000) {
m.put(null,null); // try to put in null. This may cause resize.
m.remove(null); // remove it.
Integer adding = (number += 100);
m.put(adding, null); // try to put in a number. This wont cause resize.
List<Object> new_order = new ArrayList<>();
new_order.addAll(m.keySet());
new_order.remove(adding);
if(!old_order.equals(new_order)) {
// we resized and didn't crash.
System.out.println("Encountered resize after " + (number / 100) + " iterations");
break;
}
// remember this order for the next time around.
old_order.clear();
old_order.addAll(m.keySet());
}
if(number == 100000) {
throw new Error("Resize never occurred");
}
}
}