Three major features of Java: encapsulation, inheritance, polymorphism

First, Package:

　　internal can encapsulate their own implementation details, so that the information is hidden from other categories of destruction;

　　 The division of labor between the various classes is clear, other classes do not need to care about the implementation details, class changes in the details, other classes do not need to make changes;

Second, Inherit:

Derive new classes from existing classes in order to achieve the purpose of function and attribute extension, make it easy to expand, the hierarchy between classes clear, code highly reusable;

Three, polymorphic:

System A calls the system b,b provides several ways to service A, all of which are transparent to a;

The technique of implementing polymorphism: Dynamic binding, which refers to the actual type of the referenced object during execution, calls its corresponding method according to its actual type.

There are three prerequisites for polymorphic existence: inheritance, overrides, parent-class references to child-class objects.

Benefit: Eliminate the coupling between types and facilitate flexible invocation.

Three major features of Java: encapsulation, inheritance, polymorphism