interfacekeyword. Interfaces can contain only constants, method signatures, default methods, static methods, and nested types. Method bodies exist only for default methods and static methods. Like abstract classes, Interfaces cannot be instantiated—they can only be implemented by classes or extended by other interfaces. Interface is a common way to achieve full abstraction in Java.
An interfaces specifies a list of fields and functions that may be expected on any class implementing the interface. Conversely, a class cannot implement an interface unless it has every field and function specified on the interface.
The primary benefit of using interfaces, is that it allows one to use objects of different types in a polymorphic way. This is because any class implementing the interface has at least those fields and functions.
ActiveRecord is the M in MVC which is the layer of the system responsible for representing business data and logic. The technique that connects the rich objects of an application to tables in a relational database management system is Object Relational Mapper(ORM).
ActiveRecord will perform queries on the database for you and is compatible with most database systems. Regardless of which database system you're using, the ActiveRecord method format will always be the same.