Question

In Java, I have a Set, and I want to turn it into a sorted List. Is there a method in the java.util.Collections package that will do this for me?

Answer 1

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);