tim/prune/UpdateMessageBroker.java

   1 package tim.prune;
   2
   3 /**
   4  * Class responsible for distributing update information
   5  * to all registered listeners
   6  */
   7 public abstract class UpdateMessageBroker
   8 {
   9         private static final int MAXIMUM_NUMBER_SUBSCRIBERS = 8;
  10         /** Array of all subscribers */
  11         private static DataSubscriber[] _subscribers = new DataSubscriber[MAXIMUM_NUMBER_SUBSCRIBERS];
  12         /** Index from which to start looking for an empty slot*/
  13         private static int _searchStartIndex = 0;
  14         /** Enable/disabled flag */
  15         private static boolean _enabled = true;
  16
  17
  18         /**
  19          * Add a data subscriber to the list
  20          * @param inSub DataSubscriber to add
  21          */
  22         public static void addSubscriber(DataSubscriber inSub)
  23         {
  24                 // Loop looking for first null entry
  25                 for (int i=_searchStartIndex; i<MAXIMUM_NUMBER_SUBSCRIBERS; i++)
  26                 {
  27                         if (_subscribers[i] == null)
  28                         {
  29                                 _subscribers[i] = inSub;
  30                                 _searchStartIndex = i+1;
  31                                 break;
  32                         }
  33                 }
  34         }
  35
  36         /**
  37          * Remove the given subscriber from the list
  38          * @param inSub subscriber to remove
  39          */
  40         public static void removeSubscriber(DataSubscriber inSub)
  41         {
  42                 for (int i=0; i<MAXIMUM_NUMBER_SUBSCRIBERS; i++)
  43                 {
  44                         if (_subscribers[i] == inSub)
  45                         {
  46                                 _subscribers[i] = null;
  47                                 // Could break out of the loop here but we want to make sure we remove all of them
  48                         }
  49                 }
  50                 _searchStartIndex = 0; // for the next add, start from beginning to ensure all gaps are filled
  51         }
  52
  53         /**
  54          * Enable or disable the messaging (to allow temporary disabling for multiple operations)
  55          * @param inEnabled false to disable, true to enable again
  56          */
  57         public static void enableMessaging(boolean inEnabled)
  58         {
  59                 _enabled = inEnabled;
  60         }
  61
  62         /**
  63          * Send a message to all subscribers that
  64          * the data has been updated
  65          */
  66         public static void informSubscribers()
  67         {
  68                 informSubscribers(DataSubscriber.ALL);
  69         }
  70
  71
  72         /**
  73          * Send message to all subscribers
  74          * @param inChange Change that occurred
  75          */
  76         public static void informSubscribers(byte inChange)
  77         {
  78                 // TODO: Launch separate thread so that whatever caused the inform can finish
  79                 if (!_enabled) return;
  80                 for (int i=0; i<_subscribers.length; i++)
  81                 {
  82                         if (_subscribers[i] != null)
  83                         {
  84                                 _subscribers[i].dataUpdated(inChange);
  85                         }
  86                 }
  87         }
  88
  89         /**
  90          * Send message to all subscribers
  91          * @param inMessage message to display informing of action completed
  92          */
  93         public static void informSubscribers(String inMessage)
  94         {
  95                 if (!_enabled) return;
  96                 for (int i=0; i<_subscribers.length; i++)
  97                 {
  98                         if (_subscribers[i] != null)
  99                         {
 100                                 _subscribers[i].actionCompleted(inMessage);
 101                         }
 102                 }
 103         }
 104 }