How do I sort a Set to a List in Java?
The answer provided by the OP is not the best. It is inefficient, as it creates a new List
and an unnecessary new array. Also, it raises "unchecked" warnings because of the type safety issues around generic arrays.
Instead, use something like this:
public static
<T extends Comparable<? super T>> List<T> asSortedList(Collection<T> c) {
List<T> list = new ArrayList<T>(c);
java.util.Collections.sort(list);
return list;
}
Here's a usage example:
Map<Integer, String> map = new HashMap<Integer, String>();
/* Add entries to the map. */
...
/* Now get a sorted list of the *values* in the map. */
Collection<String> unsorted = map.values();
List<String> sorted = Util.asSortedList(unsorted);
Sorted set:
return new TreeSet(setIWantSorted);
or:
return new ArrayList(new TreeSet(setIWantSorted));