java - IMplementing custom comparator -

i trying implement custom comparator beacon class (altbeacon) framework.

      collections.sort(arrays.aslist(beacons), new comparator<beacon>(){        @override        public int compare(beacon lhs, beacon rhs) {            double diff =  lhs.getdistance() - rhs.getdistance();             if (diff > 0 ){                return 1;            }             if (diff < 0 ){                return -1;            }              return 0;        }    }); 

it fails following error:

error:(176, 19) error: no suitable method found sort(list<collection<beacon>>,<anonymous comparator<beacon>>) method collections.<t#1>sort(list<t#1>) not applicable (cannot infer type-variable(s) t#1 (actual , formal argument lists differ in length)) method collections.<t#2>sort(list<t#2>,comparator<? super t#2>) not applicable (inferred type not conform upper bound(s) inferred: collection<beacon> upper bound(s): beacon,object) t#1,t#2 type-variables: t#1 extends comparable<? super t#1> declared in method <t#1>sort(list<t#1>) t#2 extends object declared in method <t#2>sort(list<t#2>,comparator<? super t#2>)

collections.sort() sorts list inplace.

what doing passing new list, after call it's not available anymore, it's useless.

put beacons in list first, sort it, use sorted list.