1. Array
Definition: A collection container that stores a data type
Features of arrays:
1. Only one data type of data can be stored
2. Once the array is initialized, the length is fixed
3. The memory addresses of the elements in the array are consecutive between the elements
Note: Arrays of type Object can store any type of data
2. Collection
Definition: A collection is a collection container that stores object data.
Advantages of sets over arrays:
1. Collections can store data of any type, while arrays can only store data of one data type
2. The length of the collection is not fixed, and the length of the array is fixed
3. Division of collections
---------------| Collection The root interface of a singleton collection
----------| List If it is a collection class that implements the list interface, it has specific characteristics: ordered, repeatable
----------| Set If a collection class that implements the set interface, it has the characteristics: unordered, non-repeatable