CheckedIdentityMap.java

/*
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 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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 *
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 * 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).
 *
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 * 2 along with this work; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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/*
 * @test
 * @bug 6585904
 * @run testng CheckedIdentityMap
 * @summary Checked collections with underlying maps with identity comparisons
 */

import org.testng.annotations.Test;

import java.util.IdentityHashMap;
import java.util.Map;

import static java.util.Collections.checkedMap;
import static org.testng.Assert.assertEquals;
import static org.testng.Assert.assertNotEquals;

public class CheckedIdentityMap {

    @Test
    public void testHashCode() {
        Map<Integer, Integer> m1 = checkedMap(
            new IdentityHashMap<Integer, Integer>(),
            Integer.class, Integer.class);
        Map<Integer, Integer> m2 = checkedMap(
            new IdentityHashMap<Integer, Integer>(),
            Integer.class, Integer.class);
        // NB: these are unique instances. Compare vs. Integer.valueOf(1)
        m1.put(new Integer(1), new Integer(1));
        m2.put(new Integer(1), new Integer(1));

        Map.Entry<Integer, Integer> e1 = m1.entrySet().iterator().next();
        Map.Entry<Integer, Integer> e2 = m2.entrySet().iterator().next();

        assertNotEquals(e1, e2);
        assertEquals(e1.hashCode(), hashCode(e1));
        assertEquals(e2.hashCode(), hashCode(e2));
    }

    static int hashCode(Map.Entry<?,?> e) {
        return (System.identityHashCode(e.getKey()) ^
                System.identityHashCode(e.getValue()));
    }
}