date-sorting

This question already has an answer here: Sorting hashmap based on keys 8 answers I trying to sort this HashMap based on date in keys My Hash map: Map<Date, ArrayList> m = new HashMap<Date, ArrayList>(); Use a TreeMap instead of HashMap . As Date already implements Comparable , it will be sorted automatically on insertion. Map<Date, ArrayList> m = new TreeMap<Date, ArrayList>(); Alternatively, if you have an existing HashMap and want to create a TreeMap based on it, pass it to the constructor: Map<Date, ArrayList> sortedMap = new TreeMap<Date, ArrayList>(m); See also: Java tutorials - Map

So, for some strange reason I end up with a 100GB log file that is unsorted ( actually it's partially sorted ), while the algorithms that I'm attempting to apply require sorted data. A line in the log file looks like so data <date> data data more data I have access to C# 4.0 and about 4 GB of RAM on my workstation. I would imagine that merge-sort of some kind would be best here, but short of implementing these algorithms myself - I want to ask if there's some kind of a shortcut I could take. Incidentally parsing the date string with DateTime.Parse() is very slow and takes up a lot of CPU time

I am using a Jquery plugin called datatables Its fantastic, however I cannot get the dates to sort correctly according to the dd/mm/yyyy format. I have looked at their support formats but none of these fixes seem to work. Can anybody here help me please? jQuery Solution Here is working jQuery solution . jQuery.extend( jQuery.fn.dataTableExt.oSort, { "date-uk-pre": function ( a ) { var ukDatea = a.split('/'); return (ukDatea[2] + ukDatea[1] + ukDatea[0]) * 1; }, "date-uk-asc": function ( a, b ) { return ((a < b) ? -1 : ((a > b) ? 1 : 0)); }, "date-uk-desc": function ( a, b ) { return ((a < b) ?