The difference between Collection and Collectes.
Collections is a class under java.util that contains a variety of static methods related to the collection.
Collection is an interface under java.util, which is a parent interface of a variety of collections.
List, SET, MAP inherits from the Collection interface? List, SET is MAP is not
ARRAYLIST and VECTOR differences.
I. Synchronization: Vector is a thread safe, that is to say is synchronized, and ArrayList is unsafe, not synchronized. Data growth: When you need to grow, Vector default growth to the original one, and arraylist It is half of the original
Differences between HashMap and HashTable
I. Historical reasons: HashTable is an implementation of the MAP interface introduced by the Java 1.2 based on the old Dictionary class.
II. Synchronization: Hashtable is a thread safe, that is, HashMap is unsafe, not synchronous
Three. Values: Only HashMap allows you to take null values as a key or value of a table
