data structures - Skip list on java extending AbstractMap -

i need implement skip list in java. know how skip list works, need extend abstractmap. class skiplist like

public class skiplist<k extends comparable<k>,v> extends abstractmap<k,v> { public skiplist(int levels) {     // ...     } // ... } 

i don't understand how need extend abstractmap

skiplist used fast search, o(logn) time complexity. standard jdk has no implementation of it. while concurrentskiplistmap implemented using skiplist data structure, can refer source code: http://grepcode.com/file/repository.grepcode.com/java/root/jdk/openjdk/8-b132/java/util/concurrent/concurrentskiplistmap.java#concurrentskiplistmap

here example: https://codereview.stackexchange.com/questions/71432/custom-skiplist-implementation-in-java