Encapsulation involves the packaging of representations by focusing on the hiding of details to facilitate abstraction, where specifications are used to describe what an entity is and what an entity does and implementations are used to describe how an entity is realized. Inheritance involves the relating and reusing of existing representations to define new representations. Polymorphism involves the ability of new representations to be defined as variations of existing representations, where new implementations are introduced but specifications remain the same such that a specification has many implementations. These pillars are used to facilitates communication, increase productivity and consistency, and enable the management of change and complexity within problem-solving efforts. Return to Contents Objects and Classes Objects and classes abstract entities .
Objects are representational constructs of entities.
Objects encapsulate structural characteristics known as attributes and behavioral characteristics known as operations. Attributes are representational constructs of structural characteristics of entities and determine the possible states of an object. Operations are representational constructs of behavioral characteristics of entities and determine the possible behaviors of an object as invoked in response to receiving a message. Objects have identity and are instances of classes. Fundamentally, objects are abstracted entities that encapsulate state and behavior.