Java Learning notes----------set Set

Java Collection-----Set
Collections: Like a container, you can put multiple objects into the container.
The Java collection is divided into: set, List, map three kinds of system.
Set: Unordered, non-repeatable;
List: Ordered, repeatable;
Map: Represents a collection of mappings, and each of the data that the map saves is a key-value pair.
Note: After Java 5, a queue system is added that represents a collection of queues implementation.

Collection and Array comparisons:
1. Once the array is initialized, the length is immutable;
2. Arrays cannot save data with mappings, such as score tables: Language---79;
3. The elements of an array can be either a primitive type or an object, and a collection can be a saved object only;

The Java collection is derived from two interfaces: collection and map, both of which are the root interfaces of the Java Collection framework.
They contain sub-interfaces and implementation classes such as

Initial study:

http://blog.csdn.net/fenglibing/article/details/8905007

Http://developer.51cto.com/art/201309/410205_all.htm

What is hashcode:

http://blog.csdn.net/fenglibing/article/details/8905007

Java Learning notes----------set Set