Hello,

I maintain a large document archive and I often use bit fields to record the status of my documents during processing or when validating them. My legacy code simply uses static int constants such as:

static int DOCUMENT_STATUS_NO_STATE = 0
static int DOCUMENT_STATUS_OK = 1
static int DOCUMENT_STATUS_NO_TIF_FILE = 2
static int DOCUMENT_STATUS_NO_PDF_FILE = 4

This makes it pretty easy to indicate the state a document is in, by setting the appropriate flags. For example:

status = DOCUMENT_STATUS_NO_TIF_FILE | DOCUMENT_STATUS_NO_PDF_FILE;

Since the approach of using static constants is bad practice and because I would like to improve the code, I was looking to use Enums to achieve the same. There are a few requirements, one of them being the need to save the status into a database as a numeric type. So there is a need to transform the enumeration constants to a numeric value. Below is my first approach and I wonder if this is the correct way to go about this?

class DocumentStatus{

    public enum StatusFlag {

        DOCUMENT_STATUS_NOT_DEFINED(1<<0),
        DOCUMENT_STATUS_OK(1<<1), 
        DOCUMENT_STATUS_MISSING_TID_DIR(1<<2),
        DOCUMENT_STATUS_MISSING_TIF_FILE(1<<3),
        DOCUMENT_STATUS_MISSING_PDF_FILE(1<<4),
        DOCUMENT_STATUS_MISSING_OCR_FILE(1<<5),
        DOCUMENT_STATUS_PAGE_COUNT_TIF(1<<6),
        DOCUMENT_STATUS_PAGE_COUNT_PDF(1<<7),
        DOCUMENT_STATUS_UNAVAILABLE(1<<8),


        private final long statusFlagValue;

        StatusFlag(long statusFlagValue) {
            this.statusFlagValue = statusFlagValue
        }

        public long getStatusFlagValue(){
            return statusFlagValue
        } 

       }


    /**
     * Translates a numeric status code into a Set of StatusFlag enums
     * @param numeric statusValue 
     * @return EnumSet representing a documents status
     */
    public EnumSet<StatusFlag> getStatusFlags(long statusValue)
    {
        EnumSet statusFlags = EnumSet.noneOf(StatusFlag.class)
        StatusFlag.each { statusFlag -> 
            long flagValue = statusFlag.statusFlagValue
            if ( (flagValue&statusValue ) == flagValue )
            {
               statusFlags.add(statusFlag)
            }
        }

        return statusFlags
    }


    /**
     * Translates a set of StatusFlag enums into a numeric status code
     * @param Set if statusFlags
     * @return numeric representation of the document status 
     */
    public long getStatusValue(Set<StatusFlag> flags)
    {
        long value=0
        flags.each { statusFlag -> 

            value|=statusFlag.getStatusFlagValue() 
        }

        return value 
    }

     public static void main(String[] args) {

        DocumentStatus ds = new DocumentStatus();
        Set statusFlags = EnumSet.of(
            StatusFlag.DOCUMENT_STATUS_OK,
            StatusFlag.DOCUMENT_STATUS_UNAVAILABLE)

        assert ds.getStatusValue( statusFlags )==258 // 0000.0001|0000.0010

        long numericStatusCode = 56
        statusFlags = ds.getStatusFlags(numericStatusCode)

        assert !statusFlags.contains(StatusFlag.DOCUMENT_STATUS_OK)
        assert statusFlags.contains(StatusFlag.DOCUMENT_STATUS_MISSING_TIF_FILE)
        assert statusFlags.contains(StatusFlag.DOCUMENT_STATUS_MISSING_PDF_FILE)
        assert statusFlags.contains(StatusFlag.DOCUMENT_STATUS_MISSING_OCR_FILE)

    }

}