73 lines
2.8 KiB
Java
73 lines
2.8 KiB
Java
/*
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* Copyright (c) 2015, Oracle and/or its affiliates. All rights reserved.
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* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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*
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* This code is free software; you can redistribute it and/or modify it
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* under the terms of the GNU General Public License version 2 only, as
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* published by the Free Software Foundation.
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*
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* This code is distributed in the hope that it will be useful, but WITHOUT
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* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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* version 2 for more details (a copy is included in the LICENSE file that
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* accompanied this code).
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*
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* You should have received a copy of the GNU General Public License version
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* 2 along with this work; if not, write to the Free Software Foundation,
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* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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*
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* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
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* or visit www.oracle.com if you need additional information or have any
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* questions.
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*/
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/**
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* @test
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* @bug 8080535
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* @summary Expected size of Character.UnicodeBlock.map is not optimal
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*/
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import java.lang.reflect.Field;
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import java.util.HashMap;
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import java.util.Map;
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public class NonOptimalMapSize {
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public static void main(String[] args) throws Throwable {
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Class<?> ubCls = Character.UnicodeBlock.class;
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Field mapField = ubCls.getDeclaredField("map");
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mapField.setAccessible(true);
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Map<?,?> map = (Map<?,?>)mapField.get(null);
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if (!map.getClass().equals(HashMap.class)) {
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throw new RuntimeException(
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"Character.UnicodeBlock.map is expected to be HashMap");
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}
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int mapSize = map.size();
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Field sizeField = ubCls.getDeclaredField("INITIAL_CAPACITY");
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sizeField.setAccessible(true);
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int INITIAL_CAPACITY = sizeField.getInt(null);
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// Construct a HashMap with specified initial capacity
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HashMap<Object,Object> map1 = new HashMap<>(INITIAL_CAPACITY);
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Class<?> hmCls = HashMap.class;
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Field tableField = hmCls.getDeclaredField("table");
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tableField.setAccessible(true);
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// ... and fill it up
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map1.put(new Object(), new Object());
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final Object initialTable = tableField.get(map1);
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while (map1.size() < map.size() &&
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initialTable == tableField.get(map1)) {
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map1.put(new Object(), new Object());
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}
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// Now check that internal storage didn't change
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if (initialTable != tableField.get(map1)) {
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throw new RuntimeException(
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"Initial capacity " + INITIAL_CAPACITY +
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" was only enough to hold " + (map1.size()-1) +
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" entries, but needed " + map.size());
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}
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}
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}
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