关于Set集合接口的看法

jdk 1.9之前与collection无差别1.9之后和list一样扩充了很多方法，新增of()方法;

元素不重复

主要子类：HashSet,TreeSet

无法使用get()方法获取指定索引数据的，

Modulejava.base

Packagejava.util

Interface Set

Type Parameters:

E- the type of elements maintained by this set

All Superinterfaces:

Collection,Iterable

All Known Subinterfaces:

EventSet,NavigableSet,ObservableSet,ObservableSetValue,SortedSet,WritableSetValue

All Known Implementing Classes:

AbstractSet,ConcurrentHashMap.KeySetView,ConcurrentSkipListSet,CopyOnWriteArraySet,EnumSet,HashSet,JobStateReasons,LinkedHashSet,ReadOnlySetProperty,ReadOnlySetPropertyBase,ReadOnlySetWrapper,SetBinding,SetExpression,SetProperty,SetPropertyBase,SimpleSetProperty,TreeSet

public interface Set
extends Collection

HashSet:实现接口Set，不重复且无

序的，利用HashCode和equals共同判断是否是相同的元素，在java中元素重复判断均是由HashCode和equals完成，除tree（treeSet）等排序外

Modulejava.base

Packagejava.util

Class HashSet

public class HashSet
extends AbstractSet
implements Set, Cloneable, Serializabl

public class TreeSet
extends AbstractSet
implements NavigableSet, Cloneable, Serializable