Question

I work on a big java project(mobile application), and got the “thankful” job to review and optimize/refactore code, because of the poor performance(high complexity).
Note: I’m totally new to Java(my background is C/C++), therefore I applogize for any dumb question.
The first thing I did, was to use Findbugs and fix all reported issues. Afterwards I used the metric tool Understand to get an overview, which
methods have a high cyclomatic complexity. Unfortunately there were a lot of methods with a cyclometic complexity above the 2^20 range 🙁
And one of them is where I would need some help or good ideas…

Short description:
For the communication with a server data has to be serialized. There is no Serializable interface available on this mobile framework.
Therefore, the colleague, who wrote all of the code(alone) implemented a Serializable interface containing one method called toByteArray().
E.g., the class Customer:

class Customer
{
    Address address;
    AttributeCollection attributes;
    LocationCollection locations;
    int recId;
    int recStatus;
    DateTime recCreated;
    String recCreatedBy;
    String recCreatedByProg;
    DateTime recChanged;
    String recChangedBy;
    String recChangedByProg;
    int refAddressesId;
    int refMandatorsId;
    CustomerPropertyUsage usage;

    /**
    * Serialize the properties of a class into a byte array.
    * @param destData Byte array, where the serialized data should be stored. Minimum 2 bytes.
    * @param serializationIndex Offset within the passed byte array, from which the serialized data of the class
    * should be entered. The offset is increased by the registered number of bytes so that after this method the
    * next call points to the serialized data subsequent byte.
    */
    void toByteArray(byte[] destData, IntClass serializationIndex)
    {
        if (this.address == null)
            this.usage.value &= ~CustomerPropertyUsage.ADDRESS;
        if (this.attributes == null)
            this.usage.value &= ~CustomerPropertyUsage.ATTRIBUTES;
        if (this.locations == null)
            this.usage.value &= ~CustomerPropertyUsage.LOCATIONS;

        this.usage.toByteArray(destData, serializationIndex);

        CatrString catrString = null;

        if ((this.usage.value & CustomerPropertyUsage.RECORD_HEADER) != CustomerPropertyUsage.NONE)
        {
            // Call static method getBytes from SerializationHelper class
            SerializationHelper.getBytes(this.recId, 4, destData, serializationIndex.value);
            serializationIndex.value += 4;

            SerializationHelper.getBytes(this.recStatus, 4, destData, serializationIndex.value);
            serializationIndex.value += 4;

            // recChanged is a DateTime object. For the serialization we need minimum a 7 bytes array,
            // Call method toByteArray() from DateTime class.
            this.recChanged.toByteArray(destData, serializationIndex);

            // call toByteArray of CatrString class
            catrString = new CatrString(this.recChangedBy);
            catrString.toByteArray(destData, serializationIndex);

            catrString.setValue(this.recChangedByProg);
            catrString.toByteArray(destData, serializationIndex);

            // Same as recChanged
            this.recCreated.toByteArray(destData, serializationIndex);

            catrString = new CatrString(this.recCreatedBy);
            catrString.toByteArray(destData, serializationIndex);

            catrString.setValue(this.recCreatedByProg);
            catrString.toByteArray(destData, serializationIndex);

            SerializationHelper.getBytes(this.refAddressesId, 4, destData, serializationIndex.value);
            serializationIndex.value += 4;

            SerializationHelper.getBytes(this.refMandatorsId, 4, destData, serializationIndex.value);
            serializationIndex.value += 4;
        }

        if (next property...)
        {
            ... Serialization ...
        }

        if (next property...)
        {
            ... Serialization ...
        }
    }
}

To keep the GPRS dues low, the server sets a value in this.usage.value and therefore only a specific property will be serialized and transmitted back to the server –>
transmitted messages are small.
This approach creates a lot of if-cases, depending on how much properties are in the class and therefore the path count gets higher and higher.
I think that’s not a beatiful solution but it’s okay. What I would like to change is the serialization calls inside the if-cases.
At the moment they look like this:

---- class SerializationHelper ----

    static void getBytes(long valueToConvert, int numOfBytesToConvert, byte[] destinationBytes, int destinationBytesOffset)
    {
        destinationBytes[destinationBytesOffset] = (byte)(valueToConvert & 0x000000FF);
        destinationBytes[destinationBytesOffset + 1] = (byte)((valueToConvert & 0x0000FF00) >> 8);

        if (numOfBytesToConvert > 2)
        {
            destinationBytes[destinationBytesOffset + 2] = (byte)((valueToConvert & 0x00FF0000) >> 16);
            destinationBytes[destinationBytesOffset + 3] = (byte)((valueToConvert & 0xFF000000) >> 24);

            if (numOfBytesToConvert > 4)
            {
                destinationBytes[destinationBytesOffset + 4] = (byte)((valueToConvert & 0x000000FF00000000L) >> 32);
                destinationBytes[destinationBytesOffset + 5] = (byte)((valueToConvert & 0x0000FF0000000000L) >> 40);
                destinationBytes[destinationBytesOffset + 6] = (byte)((valueToConvert & 0x00FF000000000000L) >> 48);
                destinationBytes[destinationBytesOffset + 7] = (byte)((valueToConvert & 0xFF00000000000000L) >> 56);
            }
        }
    }

---- class CatrString  ----

    void toByteArray(byte[] destData, IntClass serializationIndex)
    {
        //  Number of unicode characters
        SerializationHelper.getBytes(this.textLength, 2, destData, serializationIndex.value);
        serializationIndex.value += 2;

        // Text UTF-16 unicode characters
        for (int charIndex = 0; charIndex < this.textLength; charIndex++)
        {
            destData[serializationIndex.value] = (byte)(this.charCodes[charIndex] & 0x00FF);
            serializationIndex.value++;
            destData[serializationIndex.value] = (byte)((this.charCodes[charIndex] & 0xFF00) >> 8);
            serializationIndex.value++;
        }

        // Code End of string as UTF-16 unicode character
        destData[serializationIndex.value] = 0x00;
        serializationIndex.value++;
        destData[serializationIndex.value] = 0x00;
        serializationIndex.value++;
    }

---- class DateTime  ----

    void toByteArray(byte[] destData, IntClass serializationIndex)
    {
        destData[serializationIndex.value + 0] = (byte) (m_year % 0x0100);  // year low-Byte.
        destData[serializationIndex.value + 1] = (byte) (m_year / 0x0100);  // year high-Byte.
        destData[serializationIndex.value + 2] = (byte) (m_month);
        destData[serializationIndex.value + 3] = (byte) m_day;

        destData[serializationIndex.value + 4] = (byte) m_hour;
        destData[serializationIndex.value + 5] = (byte) m_minute;
        destData[serializationIndex.value + 6] = (byte) m_second;

        serializationIndex.value += 7;
    }

It should be possible to write a more “general” class which does all the serialization stuff, where I say serialize xy
bytes and that’s it. But what I don’t understand is what about “special” toByteArray() methods like for Strings(UTF-16 encoding)
or Date and Time? If I pack them in a class is that a good solution? Did I gain something with that? Maintable code? High-Performance code??
What would be your approach?

Thx

Answer 1

May be it’s better to create a Map of properties for each class. By default the set is empty but on call e.g. setAddress(address) we call fieldsMap.put(ADDRESS_KEY_STRING,address) instead of assigning to the class’ field.

To store all acesses (existing) properties we just go through the fieldsMap storing each Entry.