Databases
StackOverflow2013
Postsdbo
POImplementing a bitfield using java enums
 

Note that there are some explanatory texts on larger screens.

plurals
  1. POImplementing a bitfield using java enums
    primarykey
    data
    text
    <p>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:</p> <pre><code>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 </code></pre> <p>This makes it pretty easy to indicate the state a document is in, by setting the appropriate flags. For example: </p> <pre><code>status = DOCUMENT_STATUS_NO_TIF_FILE | DOCUMENT_STATUS_NO_PDF_FILE; </code></pre> <p>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? </p> <pre><code>class DocumentStatus{ public enum StatusFlag { DOCUMENT_STATUS_NOT_DEFINED(1&lt;&lt;0), DOCUMENT_STATUS_OK(1&lt;&lt;1), DOCUMENT_STATUS_MISSING_TID_DIR(1&lt;&lt;2), DOCUMENT_STATUS_MISSING_TIF_FILE(1&lt;&lt;3), DOCUMENT_STATUS_MISSING_PDF_FILE(1&lt;&lt;4), DOCUMENT_STATUS_MISSING_OCR_FILE(1&lt;&lt;5), DOCUMENT_STATUS_PAGE_COUNT_TIF(1&lt;&lt;6), DOCUMENT_STATUS_PAGE_COUNT_PDF(1&lt;&lt;7), DOCUMENT_STATUS_UNAVAILABLE(1&lt;&lt;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&lt;StatusFlag&gt; getStatusFlags(long statusValue) { EnumSet statusFlags = EnumSet.noneOf(StatusFlag.class); StatusFlag.each { statusFlag -&gt; long flagValue = statusFlag.statusFlagValue if ( (flagValue&amp;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&lt;StatusFlag&gt; flags) { long value=0; flags.each { statusFlag -&gt; 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); } } </code></pre>
    singulars
    1. PO
      singulars
      1. PTAnswer
    1. This table or related slice is empty.
    1. PTQuestion
    1. USDubas
    1. USsoappatrol
    plurals
    1. This table or related slice is empty.
    1. PL
      singulars
      1. LTLinked
    2. PL
      singulars
      1. LTLinked
    1. This table or related slice is empty.
    1. PO
      singulars
      1. PTAnswer
    2. PO
      singulars
      1. PTAnswer
    3. PO
      singulars
      1. PTAnswer
    1. VO
      singulars
      1. POImplementing a bitfield using java enums
      1. USDeepak
      1. VTFavorite
    2. VO
      singulars
      1. POImplementing a bitfield using java enums
      1. This table or related slice is empty.
      1. VTUpMod
    3. VO
      singulars
      1. POImplementing a bitfield using java enums
      1. USJug6ernaut
      1. VTFavorite
    1. COWhy can't you write: static int DOCUMENT_STATUS_NO_PDF_FILE = 1<<2; ?
      singulars
      1. POImplementing a bitfield using java enums
      1. USIra Baxter
    2. COReformatted code; please revert if incorrect.
      singulars
      1. POImplementing a bitfield using java enums
      1. UStrashgod
    3. COSee also [Item 32: Use EnumSet instead of bit fields](http://java.sun.com/docs/books/effective/).
      singulars
      1. POImplementing a bitfield using java enums
      1. UStrashgod
 

Querying!

 
Guidance
A row detail

Detail views are divided into sections. All the information in the data section comes from columns in the selected row. The other sections display data from other, related rows.

Related data can be related in a to-one or a to-many fashion. Captions of data related in a to-many fashion link to a list view showing a filtered view of the table.

Try moving around until you find a non-empty to-many entry and click on the label to get to one. You can move back to the root by clicking on the database name in the header.

SQuiL has stopped working due to an internal error.

If you are curious you may find further information in the browser console, which is accessible through the devtools (F12).

Reload