Java class set.Set interface

public static void main(String[] args) {
		//Set interface, cannot store duplicate elements
		//Implementation class, HashSet (unordered storage)
		//Implementation class, TreeSet (ordered storage)
		
		Set<String> treeSet = new TreeSet<String>();
		treeSet.add("1234qwer");
		treeSet.add("Look at");
		treeSet.add("qw");
		treeSet.add("abc");
		treeSet.add("999");
		
		System.out.println(treeSet);
		// output, [1234qwer, 999, abc, qw, look]

	}