Common Collection class comparisons in Java

Collection is a collection of objects, the Collection has two sub-interfaces List and set,list can be obtained by subscript (".)" To get the value, the value can be repeated , and the Set can only be used by the cursor to take the value, and the value It can't be repeated.

ArrayList, Vector, LinkedList is the implementation class for List

ArrayList is thread insecure, Vector is thread-safe, and these two classes are implemented by arrays

LinkedList is thread insecure, and the underlying is implemented by a linked list

Map is a set of key-value pairs

HashTable and HashMap are the implementation classes of Map

HashTable is thread-safe and cannot store null values

HASHMAP is not thread-safe and can store null values

Common Collection class comparisons in Java