Your logic makes sense to me ;-) Stephen ----- Original Message ----- From: "Janek Bogucki" <[EMAIL PROTECTED]> To: "Jakarta Commons Developers List" <[EMAIL PROTECTED]> Sent: Sunday, September 07, 2003 2:35 AM Subject: [collections] CollectionUtils.getCardinalityMap JavaDoc
> In CollectionUtils.getCardinalityMap the documentation notes the meaning of an entry that maps to null but I don't see how any such entry can exist in the returned map as all the keys in the map come from the collection parameter and will map to >=1. Have I missed something? > > >From CollectionUtils v 1.36 > > /** > * Returns a [EMAIL PROTECTED] Map} mapping each unique element in > * the given [EMAIL PROTECTED] Collection} to an [EMAIL PROTECTED] Integer} > * representing the number of occurences of that element > * in the [EMAIL PROTECTED] Collection}. > * An entry that maps to <tt>null</tt> indicates that the > * element does not appear in the given [EMAIL PROTECTED] Collection}. > */ > public static Map getCardinalityMap(final Collection col) { > HashMap count = new HashMap(); > Iterator it = col.iterator(); > while(it.hasNext()) { > Object obj = it.next(); > Integer c = (Integer)(count.get(obj)); > if(null == c) { > count.put(obj,new Integer(1)); > } else { > count.put(obj,new Integer(c.intValue() + 1)); > } > } > return count; > } > > > -Janek > > --------------------------------------------------------------------- > To unsubscribe, e-mail: [EMAIL PROTECTED] > For additional commands, e-mail: [EMAIL PROTECTED] > --------------------------------------------------------------------- To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED]