How to convert Collection(map.values()) to normal Set?

Question

Java

There is a Map:
{English=[Antony], Chemistry=[John], Music=[Antony]}
When using map.values() returns , you need to translate this whole thing into Set, getting rid of duplicates. I only came to the trail. option:

Set<String> uniqueStudents = new HashSet<>();
        for (List<String> listName: map.values()) {
            uniqueStudents.add(listName.get(0));
        }
        System.out.println(uniqueStudents); // [John, Antony]

Maybe someone knows a better solution?

Answer 1

Or the question is strange, or one of the two ... what does not suit the simplest solution?

Set<String> uniqueStudents = new HashSet<>(map.values());

PS: didn't notice that map values ​​are arrays of strings, not strings. Then you really need to:

Set<String> set = map.values().stream()
                               .map(a -> a[0])
                               .collect(Collectors.toSet());