I have a HTML list of about 500 items and a "filter" box above it. I started by using jQuery to filter the list when I typed a letter (timing code added later): $('#filter').keyup( function() { var jqStart = (new Date).getTime(); var search = $(this).val().toLowerCase(); var $list = $('ul.ablist > li'); $list.each( function() { if ( $(this).text().toLowerCase().indexOf(search) === -1 ) $(this).hide(); else $(this).show(); } ); console.log('Time: ' + ((new Date).getTime() - jqStart)); } ); However, there was a couple of seconds delay after typing each letter (particularly the first letter). So I thought it may be slightly quicker if I used plain Javascript (I read recently that jQuery's each function is particularly slow). Here's my JS equivalent: document.getElementById('filter').addEventListener( 'keyup', function () { var jsStart = (new Date).getTime()...
You should use ArrayList instead of Vector. Vector used internal synchronisation, but that is rarely good enough for actual consistency, and only slows down execution when it is not really needed.
ReplyDeleteAlso see this stackoverflow question.
You can use an ArrayList instead.
ReplyDeleteIf you need a synchronized version, you can do something like:
ArrayList arrayList = new ArrayList();
List synchList = Collections.synchronizedList(arrayList);
ArrayList is now the better class to use. Vector is now considered Legacy, and has the added performance overhead of being Thread-Safe.
ReplyDeleteVector is a legacy collection class from Java 1.0. In Java 1.2 (long ago!), the Collections Framework was added which included new collection classes such as ArrayList and HashMap, which were intended to replace the legacy classes Vector and Hashtable.
ReplyDeleteAs said before, the legacy collection classes had built-in synchronization, which is unnecessary for many applications. Synchronization has a performance overhead, so if it's not necessary, you shouldn't use it.
In some cases (when your program is multi-threaded, and multiple threads access the same data) you need to synchronize your collections. Some people would then use the old Vector or Hashtable classes, but a better way is to use a synchronization wrapper with for example an ArrayList:
// Your standard, unsynchronized list
List<String> data = new ArrayList<String>();
// Use this to put it into a synchronization wrapper
List<String> syncedData = Collections.synchronizedList(data);
See the API documentation of Collections.synchronizedList() (and other methods) for more information.
Use ArrayList when you need a List implementation but don't need thread safety, and use CopyOnWriteArrayList when you need a List implementation that is thread safe.
ReplyDelete