bug in UserAgent.equals()

[drobert]

As part of a serialization test I was running, I noticed that when UserAgent.EMPTY is serialized then deserialized, after.equals(before) returns false.

It appears it's due to this line:

if (deviceCategory != other.deviceCategory) {
    return false;
}

Even though DeviceCategory is final, it does not guarantee the categories are the same object instance. I believe this should fix it, though I'll submit a PR once I have a test written:

if (!deviceCategory.equals(other.deviceCategory)) {
    return false;
}

A test to reproduce this issue:

public class ExampleTest {

    @Test
    public equalsFailsAfterSerDeser() throws Exception {
        UserAgent before = UserAgent.EMPTY;
        UserAgent after = SerializationUtils.deserialize(SerializationUtils.serialize(item));
 
        assertEquals(before, after);
    }

    /**
     * Lifted directly from SpringFramework 4.1.6.Release
     * @see org.springframework.util.SerializationUtils
     */
    static final class SerializationUtils {
        private SerializationUtils() { }

        /**
         * Serialize the given object to a byte array.
         * @param object the object to serialize
         * @return an array of bytes representing the object in a portable fashion
         */
        public static byte[] serialize(Object object) {
            if (object == null) {
                return null;
            }
            ByteArrayOutputStream baos = new ByteArrayOutputStream(1024);
            try {
                ObjectOutputStream oos = new ObjectOutputStream(baos);
                oos.writeObject(object);
                oos.flush();
            }
            catch (IOException ex) {
                throw new IllegalArgumentException("Failed to serialize object of type: " + object.getClass(), ex);
            }
            return baos.toByteArray();
        }

        /**
         * Deserialize the byte array into an object.
         * @param bytes a serialized object
         * @return the result of deserializing the bytes
         */
        public static Object deserialize(byte[] bytes) {
            if (bytes == null) {
                return null;
            }
            try {
                ObjectInputStream ois = new ObjectInputStream(new ByteArrayInputStream(bytes));
                return ois.readObject();
            }
            catch (IOException ex) {
                throw new IllegalArgumentException("Failed to deserialize object", ex);
            }
            catch (ClassNotFoundException ex) {
                throw new IllegalStateException("Failed to deserialize object type", ex);
            }
        }
    }
}