1 /*

     2  * Copyright (c) 2015, 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.

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    23 

    24 

    25 /**

    26  * @test

    27  * @bug 8080535

    28  * @summary Expected size of Character.UnicodeBlock.map is not optimal

    29  */

    30 

    31 import java.lang.reflect.Field;

    32 import java.util.HashMap;

    33 import java.util.Map;

    34 

    35 public class NonOptimalMapSize {

    36     public static void main(String[] args) throws Throwable {

    37         Class<?> ubCls = Character.UnicodeBlock.class;

    38         Field mapField = ubCls.getDeclaredField("map");

    39         mapField.setAccessible(true);

    40         Map<?,?> map = (Map<?,?>)mapField.get(null);

    41         if (!map.getClass().equals(HashMap.class)) {

    42             throw new RuntimeException(

    43                     "Character.UnicodeBlock.map is expected to be HashMap");

    44         }

    45         int mapSize = map.size();

    46 

    47         Field sizeField = ubCls.getDeclaredField("INITIAL_CAPACITY");

    48         sizeField.setAccessible(true);

    49         int INITIAL_CAPACITY = sizeField.getInt(null);

    50 

    51         // Construct a HashMap with specified initial capacity

    52         HashMap<Object,Object> map1 = new HashMap<>(INITIAL_CAPACITY);

    53         Class<?> hmCls = HashMap.class;

    54         Field tableField = hmCls.getDeclaredField("table");

    55         tableField.setAccessible(true);

    56         // ... and fill it up

    57         map1.put(new Object(), new Object());

    58         final Object initialTable = tableField.get(map1);

    59         while (map1.size() < map.size() &&

    60                 initialTable == tableField.get(map1)) {

    61             map1.put(new Object(), new Object());

    62         }

    63 

    64         // Now check that internal storage didn't change

    65         if (initialTable != tableField.get(map1)) {

    66             throw new RuntimeException(

    67                     "Initial capacity " + INITIAL_CAPACITY +

    68                     " was only enough to hold " + (map1.size()-1) +

    69                     " entries, but needed " + map.size());

    70         }

    71     }

    72 }