Introduction to ObjectOriented Programming（介绍面向对象编程）.pdfVIP

Introduction to Obj ect-Oriented Programming • Objects and classes • Abstract Data Types (ADT) • ncapsulation and information hiding • Aggregation • Inheritance and polymorphism OOP: Introduction 1 Pure Obj ect-Oriented Languages Five rules [Source: Alan Kay]: • verything in an object. • A program is a set of objects telling each other what to do by sending messages. • ach object has its own memory (made up by other objects). • very object has a type. • All objects of a specific type can receive the same messages. Java breaks some of these rules in the name of efficiency. OOP: Introduction 2 The Obj ect Concept • An object is an encap sulation of data. • An object has  identity (a unique reference),  state, also called characteristics  behavior • An object is an instance of an abstract data typ e. • An abstract data type is implemented via a class. OOP: Introduction 3 Abstract Data Type (ADT) • An ADT is a collection of obj ects (or values) and a corresponding set of methods. • An ADT encapsulates the data representation and makes data access possible at a higher level of abstraction. • xample 1: A set of vehicles with operations for starting, stopping, driving, get km/liter, etc.. • xample 2: A time interval, start time, end time, duration, overlapping intervals, etc. OOP: Introduction 4 ncapsulation and Information Hiding • Data can be encapsulated such that it is invisible to the outside world. • Data can onl