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Java example source code file (Serial.java)

This example Java source code file (Serial.java) is included in the alvinalexander.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" TM.

Learn more about this Java project at its project page.

Java - Java tags/keywords

bytearrayoutputstream, doubleaccumulator, doubleadder, ioexception, longaccumulator, longadder, longbinaryoperator, objectinputstream, objectoutputstream, runtimeexception, serializable, serializationproxy, string, unexpected

The Serial.java Java example source code

/*
 * Copyright (c) 2013, 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 8026344
 * @summary Exercise classes in j.u.c.atomic that use serialization proxies
 */

import java.util.concurrent.atomic.DoubleAdder;
import java.util.concurrent.atomic.DoubleAccumulator;
import java.util.concurrent.atomic.LongAdder;
import java.util.concurrent.atomic.LongAccumulator;
import java.util.function.DoubleBinaryOperator;
import java.util.function.LongBinaryOperator;
import java.io.ByteArrayOutputStream;
import java.io.ByteArrayInputStream;
import java.io.DataInputStream;
import java.io.Serializable;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.io.IOException;

/**
 * Basic test to exercise the j.u.c.atomic classes that use serialization
 * proxies.
 */

public class Serial {

    public static void main(String[] args) {
        testDoubleAdder();
        testDoubleAccumulator();
        testLongAdder();
        testLongAccumulator();
    }

    static void testDoubleAdder() {
        DoubleAdder a = new DoubleAdder();
        a.add(20.1d);
        DoubleAdder result = echo(a);
        if (result.doubleValue() != a.doubleValue())
            throw new RuntimeException("Unexpected doubleValue");

        checkSerialClassName(a, "java.util.concurrent.atomic.DoubleAdder$SerializationProxy");
    }

    static void testDoubleAccumulator() {
        DoubleBinaryOperator plus = (DoubleBinaryOperator & Serializable) (x, y) -> x + y;
        DoubleAccumulator a = new DoubleAccumulator(plus, 13.9d);
        a.accumulate(17.5d);
        DoubleAccumulator result = echo(a);
        if (result.get() != a.get())
            throw new RuntimeException("Unexpected value");
        a.reset();
        result.reset();
        if (result.get() != a.get())
            throw new RuntimeException("Unexpected value after reset");

        checkSerialClassName(a, "java.util.concurrent.atomic.DoubleAccumulator$SerializationProxy");
    }

    static void testLongAdder() {
        LongAdder a = new LongAdder();
        a.add(45);
        LongAdder result = echo(a);
        if (result.longValue() != a.longValue())
            throw new RuntimeException("Unexpected longValue");

        checkSerialClassName(a, "java.util.concurrent.atomic.LongAdder$SerializationProxy");
    }

    static void testLongAccumulator() {
        LongBinaryOperator plus = (LongBinaryOperator & Serializable) (x, y) -> x + y;
        LongAccumulator a = new LongAccumulator(plus, -2);
        a.accumulate(34);
        LongAccumulator result = echo(a);
        if (result.get() != a.get())
            throw new RuntimeException("Unexpected value");
        a.reset();
        result.reset();
        if (result.get() != a.get())
            throw new RuntimeException("Unexpected value after reset");

        checkSerialClassName(a, "java.util.concurrent.atomic.LongAccumulator$SerializationProxy");
    }

    /**
     * Serialize the given object, returning the reconstituted object.
     */
    @SuppressWarnings("unchecked")
    static <T extends Serializable> T echo(T obj) {
        ByteArrayOutputStream out = new ByteArrayOutputStream();
        try (ObjectOutputStream oos = new ObjectOutputStream(out)) {
            oos.writeObject(obj);
        } catch (IOException e) {
            throw new RuntimeException("Serialization failed: " + e);
        }
        ByteArrayInputStream in = new ByteArrayInputStream(out.toByteArray());
        try (ObjectInputStream ois = new ObjectInputStream(in)) {
            return (T) ois.readObject();
        } catch (IOException | ClassNotFoundException e) {
            throw new RuntimeException("Deserialization failed: " + e);
        }
    }

    /**
     * Checks that the given object serializes to the expected class.
     */
    static void checkSerialClassName(Serializable obj, String expected) {
        String cn = serialClassName(obj);
        if (!cn.equals(expected))
            throw new RuntimeException(obj.getClass() + " serialized as " + cn
                + ", expected " + expected);
    }

    /**
     * Returns the class name that the given object serializes as.
     */
    static String serialClassName(Serializable obj) {
        ByteArrayOutputStream out = new ByteArrayOutputStream();
        try (ObjectOutputStream oos = new ObjectOutputStream(out)) {
            oos.writeObject(obj);
        } catch (IOException e) {
            throw new RuntimeException("Serialization failed: " + e);
        }
        ByteArrayInputStream in = new ByteArrayInputStream(out.toByteArray());
        try (DataInputStream dis = new DataInputStream(in)) {
            dis.readShort();      // STREAM_MAGIC
            dis.readShort();      // STREAM_VERSION
            dis.readByte();       // TC_OBJECT
            dis.readByte();       // TC_CLASSDESC
            return dis.readUTF(); // className
        } catch (IOException e) {
            throw new RuntimeException(e);
        }
    }
}

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