How to initialize a Set in Java?

To initialize a Set in Java, do this: new HashSet(Arrays.asList(values)).

HashSet takes a Collection as an argument, so if you want to initialize your Set in a single line, then use Arrays.asList to supply your values.

Set<String> set = new HashSet<>(Arrays.asList("one", "two", "three"));

System.out.println(set); // [one, two, three]