Question

I need to define a customized comparator to ConcurrentSkipListMap, I use this code to sort based on ‘LogicalClock’ but the result is not as I expected. I create the key like this: “ClientId”+”:”+”LogicalClock”

class Qentry{
    int  AckCount;
    int ClientID; 
    long LogicalClock;
}

Comparator<String> LogicalClockComparator = new Comparator<String>() {
        @Override public int compare(String k1, String k2) {
            if  (k1.compareTo(k2)==0)
                    return 0;
            return   (int)( Long.valueOf(k1.substring(k1.indexOf(":")+1)) -Long.valueOf(k2.substring(k1.indexOf(":")+1) ));
        }
ConcurrentSkipListMap<String,Qentry> q;
q =new ConcurrentSkipListMap<String,Qentry>(LogicalClockComparator);

Answer 1

Looks like a typo (or copy/paste error) to me, maybe you want to use (look at the end of the line)

return   (int)( Long.valueOf(k1.substring(k1.indexOf(":")+1)) -Long.valueOf(k2.substring(k2.indexOf(":")+1) ));

instead of what you had:

return   (int)( Long.valueOf(k1.substring(k1.indexOf(":")+1)) -Long.valueOf(k2.substring(k1.indexOf(":")+1) ));