Java Collection Learning (15) Set schema

Previously, we have systematically studied the list and map. Next, we can begin to learn set. It is much easier to learn set after map understanding. After all, set implementation classes are implemented based on a map (HashSet is implemented through HASHMAP, TreeSet is implemented through TreeMap).

First, let's look at the set schema.

Set is an interface that inherits from collection. It is a collection that is not allowed to have duplicate elements.
Abstractset is an abstract class that inherits from Abstractcollection,abstractcollection to implement most of the functions in set and facilitates the implementation classes of set.

Hastset and TreeSet are two implementation classes of set.

HashSet relies on HashMap, which is actually implemented through HashMap. The elements in the hashset are unordered.

TreeSet relies on TreeMap, which is actually implemented through TREEMAP. The elements in the TreeSet are ordered.

See more highlights of this column: http://www.bianceng.cnhttp://www.bianceng.cn/Programming/Java/