import ?java.util.*;class ? CollectionsDemo2{ public ?static ?void ?main(String[] ?args) {sortDemo(); } public ?static ?void ?binarySearchDemo() { List<String> ? list=new ?ArrayList<String>(); list.add("abcd"); list.add("aaa"); list.add("zzzz"); list.add("kkkk"); list.add("z"); Collections.sort(list,new StrLenComparator()); sop(list); } public ?static ?void ?orderDemo() { TreetSet<String>ts=new ?TreeSet<String>(Collections.reverseOrder(new ? StrLenComparator())); ts.add("abcde"); ts.add("aaa"); ts.add("kk"); ts.add("ddd"); ts.add("eee"); Iterator ? it=ts.iterator(); while(it.hasNext()) { System.out.println(it.next()); } }}