Object Oriented Programming FILS 2012-2013 fileBibliography The lectures are not enough, extra reading is necessary Romanian: •L.D.Serbanati, C.Bogdan, Programare orientata spre

Object Oriented Programming FILS 2014-2015

Andrei Vasilateanu, PhD

Administration

Course Master:

• Andrei Vasilateanu, andraevs@gmail.com

Teaching Assistants: • Radu Ioanitescu, ioanitescuradu@yahoo.com

Grading: • Final exam 40%

• Laboratory 60% • 2 Tests 30%

• Attendance 10%

• Homework + Activity 20%

Course Policies:

• Individual HW, >50% in exam, no late HW

mailto:andraevs@gmail.com

Bibliography

The lectures are not enough, extra reading is necessary

Romanian:

• L.D.Serbanati, C.Bogdan, Programare orientata spre obiecte cu exemplificari in limbajul Java, vol 2

English:

• C. Horstmann, G. Cornell, “Core Java 2”

• K.Mughal, R. Rasmussen, “Programmer's Guide to Java SCJP Certification”

• http://docs.oracle.com/javase/tutorial/

• J. Bloch, C. Persuati, “Effective Java”

• S. McConnell, “Code Complete”

http://docs.oracle.com/javase/tutorial/

Overview of the course

Revision of basic OOP concepts from PL

Interfaces

Nested classes

Generics

Collections

Graphical User Interfaces (AWT + Swing)

Exception Handling

Concurrency

Reflexion

Revision Object Oriented Programming

Programming paradigm

• Data + functions

• Code reuse

• Object Oriented Analysis and Design

O1

O4 O3

O2 m1

m3

m2

Concepts

A concept is an idea or notion that we apply to entities in the real world or our imagination

1. For us, concepts are a recognition device. The concepts may be: Tangible (person, car, table), Intangible (time, quality, company), Roles

(doctor, patient, owner), Judgments (high pay, good example, productive job), Relational (marriage, partnership, ownership), Events (sale, purchase, market crash), Other types of concepts (string, number, icon, image, signal, process)

2. For us concepts are also a test for reality: we can apply concepts to entities in our reality and discard concepts that no longer apply. Each concept is based on tests that determine when it applies.

Person Employee

Company

Headquarter

Car

Model

Patient

Efficient Organization

Contract

can be a can be a

owns employs

characterizes

has

is an instance of

subject

owns

subscribes

Town

lives in

registered

registered at

Marriage

Concept We use concepts as units of knowledge in which each has an intension and

an extension. There two sides of the same coin. • Intension (definition, understanding): the complete definition of the concept and

the test that determines whether or not the concept applies to an entity. • Extension: the set of all entities to which the concept applies.

A domain is a collection of entities in a selected area of interest. A domain specification is the collection of concepts that apply to a domain. An instance of a concept is an entity in the real world or our imagination to

which a concept applies.

{ Extension }

{ Intension }

A shared notion or idea that applies to certain objects in our awareness.

Type (i.e. Concept)

Person

Employee

Event Type

Company

Order Item

Order

{ Symbolizes }

Manager

Objects Objects in OOP programming are computer-oriented representations of

concept instances. Each object in our programs should abstract a concept instance in the real

world or our imagination. Three key characteristics of objects derived from characteristics of the real

entities: • The object's behaviour - what can you do with this object, or what methods can

you apply to it? The behaviour of an object is defined by the methods that you can call. The state of an object can influence its behaviour .

• The object's state - how does the object react when you apply those methods? the object's state is all stored information about what it currently looks like. A change in the state of an object must be a consequence of method calls.

• The object's identity - how is the object distinguished from others that may have the same behaviour and state? The state of an object does not completely describe it, since each object has a distinct identity.

A class of objects is the description of a set of similar objects with the same state components and behaviour.

Classification is the act or result of applying a concept (i.e. type) to one of its instances. Further we can define classification in the OOP programming:

Class Object

classifier

instance

1..*

*

Classification Relationship

Relationships Between Classes

The most common relationships between classes are: • Dependence ("uses–a"): a class depends on another class if its methods

manipulate objects of that class. • Association ("knows–a"): A user-defined relationship. • Aggregation ("has–a"): the act or result of forming an object whole

using other objects as its parts • Generalization ("is–a"): the act or result of distinguishing a concept (i.e.

type) that completely includes or encompasses another.

Order

RushOrder

Item Account check for credit

*

OrderManager

*

Generalization Generalization is the act or result of distinguishing a concept (i.e. type) that

completely includes or encompasses another. Generalization enables us to say that all instances of a specific type are also

instances of more general type – but not necessarily the other way around. With generalization we can define hierarchies of types, forming more and

more general types. The more general type is called supertype. The opposite of generalization is specialization. The specialized types are subtypes.

Generalization in Java is expressed as class extension. In general, if class A extends class B, class A inherits variables and methods

from class B, but has more capabilities.

Inheritance

Code reuse in OO = create new classes that are built upon existing classes.

Polymorphism = An object variable (such as the variable e) can

refer to multiple actual types.

Constructor inheritance

Method overriding • Covariant return (only reference types)

• Accesibility

• @Override

• Exception throwing

Method and field hiding

Cohesion and Coupling

Cohesion = inter-class measure of how well-structured and closely-related the functionality is in a class. => well-defined and related tasks

Coupling = measure of intra-class dependencies.

High cohesion and loose coupling => maintanability, reusability, extensibility and reliability