java用接口实例化和直接实例化有什么区别？

Question

Collection hs1 = new HashSet<>();
Set hs2 = new HashSet<>();
HashSet hs3 = new HashSet<>();

请问以上三种方法实例化出来的对象有什么区别？

Answer 1

    Collection<Character> hs1 = new HashSet<>();
    Set<Character> hs2 = new HashSet<>();
    HashSet<Character> hs3 = new HashSet<>();