A Set is a generic set of values with no duplicate elements. A TreeSet is a set where the elements are sorted.
A HashSet is a set where the elements are not sorted or ordered. It is faster than a TreeSet. The HashSet is an implementation of a Set.
Set is a parent interface of all set classes like TreeSet, HashSet, etc.
import java.util.*; public class Demo { public static void main(String args[]) { int a[] = {77, 23, 4, 66, 99, 112, 45, 56, 39, 89}; Set<Integer> s = new HashSet<Integer>(); try { for(int i = 0; i < 5; i++) { s.add(a[i]); } System.out.println(s); TreeSet sorted = new TreeSet<Integer>(s); System.out.println("Sorted list = "); System.out.println(sorted); } catch(Exception e) {} } }
[66, 99, 4, 23, 77] Sorted list = [4, 23, 66, 77, 99]