Re: How to tell if an a date occurs multiple times in an array/collection

laredotornado wrote:


If you load the data into a 'Set <Calendar>' you cannot have any
duplicates.

 Set <Calendar> calends =
    new HashSet <Calendar> ( Arrays.asList( getArrayOfCalendars() ));

You can iterate over the array and load the counts into a
'Map <Calendar, Integer>'.

 Map <Calendar, Integer> counts =
   new HashMap <Calendar, Integer>
   ( getArrayOfCalendars() .length * 4 / 3 );
 for ( Calendar calend : getArrayOfCalendars() )
 {
   Integer k = counts.get( calend );
   counts.put( calend, (k == null? 1 : k + 1) );
 }
 for ( Map.Entry <Calendar, Integer> entry : counts.entrySet() )
 {
   if ( entry.getValue() > 1 )
   {
     System.out.println( "Duplicates found for "+ entry.getKey() );
   }
 }

This should be about O(n) for performance.

--
Lew