ComputeIfAbsentAccessOrder.java

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 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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 * 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).
 *
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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 8030016
 * @summary computeIfAbsent would generate spurious access
 */

import java.util.*;

public class ComputeIfAbsentAccessOrder {
    public static void main(String args[]) throws Throwable {
        LinkedHashMap<String,Object> map = new LinkedHashMap<>(2, 0.75f, true);
        map.put("first", null);
        map.put("second", null);

        map.computeIfAbsent("first", l -> null); // should do nothing

        String key = map.keySet().stream()
                .findFirst()
                .orElseThrow(() -> new RuntimeException("no value"));
        if(!"first".equals(key)) {
            throw new RuntimeException("not expected value " + "first" + "!=" + key);
        }
    }
}