Java Container Learning

A container is an important part of Java, and its interface is structured as follows

Collection

|

------------------Map

|　　　　　　　　| |

Set List HashMap

|

HashSet

As the name implies, the container is used to store things, for objects, the container is essentially a reference to the object, that is, the object's address.

The collection interface has two sub-interfaces set and list, in addition to being used to store elements of this commonality, respectively, have different characteristics.

The container of the list category generally has an orderly character, when the element is inserted and deleted, the order of the elements is maintained, and duplicate elements can be placed.

The container of the set class does not allow repeating elements to be placed, and is generally unordered.

The container for the map category stores the object and the only mapping that can identify the primary key of the object, and cannot place duplicate primary keys.

Java Container Learning