import java.util.*;
import java.util.stream.*;
public class MyClass {
public static void main(String args[]) {
Set<Integer> seti = new HashSet<>(Arrays.asList(1, 2, 3, 4, 5, 6));
Set<String> sets = seti.stream().map(String::valueOf)
.collect(Collectors.toSet());
System.out.println(sets);
}
}
/*
run:
[1, 2, 3, 4, 5, 6]
*/