Oriented Programming Concepts and Principles
- 1. Object-Oriented Programming Concepts and Principles New Wave Analytica We Find Solutions in Data
- 2. Outline ▪ Abstraction ▪ Structured Programming ▪ Procedural vs. Object-Oriented Programming ▪ Goals of Object-Oriented Programming ▪ Principles of Object-Oriented Programming New Wave Analytica
- 3. Abstraction ▪ One of the prime concepts used to simplify programming problems ▪ Mechanism and practice to reduce and factor out details so that one can focus on a few concepts at a time. ▪ Through the process of abstraction, a programmer hides all but the relevant data about an object in order to reduce complexity and increase efficiency. ▪ Abstraction is one of the key concepts of object-oriented programming (OOP) languages. ▪ Its main goal is to handle complexity by hiding unnecessary details from the user. ▪ That enables the user to implement more complex logic on top of the provided abstraction without understanding or even thinking about all the hidden complexity. New Wave Analytica
- 4. Abstraction
- 5. Structured Programming ▪ Further refinement of procedural programming ▪ Formal methods of planning data flow and functional decomposition ▪ go to is banned
- 6. Structured Programming ▪ A programming paradigm aimed at improving the clarity, quality, and development time of a computer program by making extensive use of the structured control flow constructs ▪ Selection (if/then/else) ▪ Repetition (while and for) ▪ Block structures ▪ Subroutines ▪ A programming paradigm in contrast to using simple tests and jumps such as the go to statement. New Wave Analytica
- 7. Procedural Programming ▪ A programming model which is derived from structured programming, based upon the concept of calling procedure. ▪ Procedures, also known as routines, subroutines or functions, simply consist of a series of computational steps to be carried out. ▪ During a program’s execution, any given procedure might be called at any point, including other procedures or itself. ▪ Languages ▪ Basic ▪ Pascal ▪ C New Wave Analytica
- 8. Procedural Programming ▪ Routines are grouped into functions ▪ A function can call another function ▪ You don’t have to understand each line, lust what each function did ▪ You could hide data to be accessible to only within a function (encapsulation) New Wave Analytica
- 9. Object-Oriented Programming (OOP) ▪ Takes encapsulation even further by localizing data and associated operations into a mini-program called an object. ▪ An object-oriented program is an ecosystem of objects that interact with each other. ▪ “Think of an object-oriented system as a bunch of intelligent animals as objects inside your machine, talking to each other by sending messages to one another.” – Alllan Holub New Wave Analytica
- 10. Object-Oriented Programming (OOP) ▪ A programming model which is based upon the concept of objects. ▪ Objects contain data in the form of attributes and code in the form of methods. ▪ In OOP, computer programs are designed using the concept of objects that interact with real world. ▪ OOP languages are various but the most popular ones are class-based, meaning that objects are instances of classes, which also determine their types. ▪ OOP takes abstraction farthest by allowing you to group related data and operations into different types of objects. ▪ You create your own data types, which are types of objects. Each of these data types are called objects. New Wave Analytica
- 11. Object-Oriented Programming (OOP) ▪ Creating you own classes allows you to design a program so that it is intuitive to remember how it is organized ▪Example ▪ Creating classes that represent real world entities. ▪ Creating classes to have specific responsibilities so that when you need to update a piece of code, you know exactly where to look for it ▪ Languages ▪ Java, C++, C#, Python, PHP, JavaScript ▪ Ruby, Perl, Objective-C, Dart, Swift, Scala New Wave Analytica
- 12. Goals of Object-Oriented Programming ▪ Comprehensibility ▪ Make it easier for humans to understand you code ▪ Maintainability ▪ Make code easy to modify ▪ Reusability ▪ Old code should be building blocks for new code ▪ Plugability ▪ You can create interchangeable component that can substitute for one another just like machine parts. New Wave Analytica
- 13. Class and Objects ▪ A class in Java is a blueprint for objects to follow a specific schema defined in the class. ▪ A class defines the behavior for objects of its type. It represents a collection of properties (data and functions) for all its objects. ▪ It supports a template for creating objects which bind code and data. ▪ A class acts as a means to define methods and data. ▪It helps in maintaining access specifications for member variables using access specifiers. New Wave Analytica
- 14. Class and Objects ▪ An object is the most fundamental entity in Java ▪ Objects represent real-life entities because each of them could have specific behavior, identity, and data (attributes). ▪ In Java, the object is an offspring of its class. ▪ The class has properties to reflect the object state and methods to represent the behavior. ▪ The methods also show an object’s response to other objects. Identity is a unique name for the object assigned by the user, much like variables. New Wave Analytica
- 15. What is a Class and an Instance of a Class? ▪ Class ▪ Definition of an object ▪ Example: ▪ Your car is a 2018 BMW 3-series ▪ Instance ▪ The created object of a class ▪ Example : ▪ There are many other 2018 BMW 3-series out there but there is only one instance of your car. New Wave Analytica
- 16. What is an object? ▪ Has attributes ▪ a property or components ▪ Has methods ▪ behaviours or routines New Wave Analytica
- 17. Example of an Object - Car ▪ Attributes ▪ steering wheel ▪ engine ▪ color ▪ radio ▪ airconditoiner ▪ Methods ▪ go forward ▪ go backward ▪ cool the interior ▪ play music New Wave Analytica
- 18. What is an interface? ▪ An object has an interface ▪ The outward appearance of an object. How other objects see the object ▪ The attributes and methods that the object exposes. ▪ Normally, an object will only expose some of its attributes and methods. ▪ Some attributes and methods are used by the object itself. Therefore, no other object should have access to those ▪ Some attribute and methods may be made accessible only to certain other objects. ▪ Some attributes and methods may be accessible by any other object New Wave Analytica
- 19. What is an interface? ▪ Normally, only methods are exposed. Objects usually hide their data to protect then from being changed by other objects without their control ▪ Constants are an exception. These don’t change anyway New Wave Analytica
- 20. Three Core Principles of OOP ▪ Encapsulation ▪ Inheritance ▪ Polymorphism New Wave Analytica
- 21. Encapsulation ▪ It is a mechanism of wrapping the data (variables) and code acting on the data (methods) together as a single unit. ▪ In encapsulation, the variables of a class will be hidden from other classes, and can be accessed only through the methods of their current class. ▪ Grouping of data and operations into objects. ▪ Related data and operations should not be separated. They should be found in a single object. ▪ It is also known as data hiding New Wave Analytica
- 22. Encapsulation ▪To achieve encapsulation in Java ▪ Declare the variables of a class as private. ▪ Provide public setter and getter methods to modify and view the variables values. ▪ Benefits of Encapsulation ▪ The fields of a class can be made read-only or write-only ▪ A class can have total control over what is stored in its fields ▪ Simpler interfaces ▪ Only a few methods are exposed to other objects. Since interactions between objects are simple, system us easier for the programmer to comprehend. ▪ Data protected from corruption ▪ Easier to modify code or find bugs ▪ Simpler interactions New Wave Analytica
- 23. Examples of Encapsulation ▪ You shouldn’t have to ask someone with radar gun to measure the speed of your car. Your car should have its own speedometer. ▪ Purchase Order Object ▪ Data for purchase orders should not be lumped in the same objects as data for invoices and receipts ▪ The methods for retrieving data from a purchase order should not be found in a separate class from the data. ▪ DB Connection Object ▪ The DB Connection object should not need to look up the URL from the database from another object every time its does an operation. New Wave Analytica
- 24. Examples of Encapsulation ▪ Information Hiding ▪ AN object should expose only what is necessary, and only at the appropriate level. ▪ Think of CIA … “need-to-know” New Wave Analytica
- 25. Examples of Encapsulation ▪ Car ▪ Driver : Only steering wheel, pedals, and stick shift are exposed. Driver should not access engire or gears or axle to drive the car ▪ Mechanic ▪ Access to engine, gears, etc., but not internals of each part ▪Manufacturer ▪ Access to internals of each part New Wave Analytica
- 26. Examples of Encapsulation ▪ Purchase Order Object ▪ Any object can get into from the object, but only certain objects should have authority to set information. ▪ Only certain objects should be allowed to create PO object ▪ DB Connection Object ▪ Only the Driver Manager object can create a connection ▪ Users cannot set whether a connection is read-only or not. New Wave Analytica
- 27. Inheritance ▪ It is a way to create a new class by deriving from another class. ▪ It is the mechanism in java by which one class is allowed to inherit the features(fields and methods) of another class. ▪ Interface Inheritance ▪ The new class acquires the interface of the old class ▪ Implementation Inheritance ▪ The new class often also acquires the implementation of the old class ▪ The new class can change the implementation of the older class or ass its methods and attributes. New Wave Analytica
- 28. Inheritance ▪ Inheritance is a way to allow objects to share code, preventing code- duplication ▪ Code supplication is the number sin in OOP ▪ Implementation inheritance is dangerous ▪ The Fragile Base Class Problem ▪ A subclass must inherit all inheritable members of the superclass ▪ No option to disinherit a member ▪ If the subclass inherits members that it doesn’t need, those members might be called by other objects in a way that the creator of the subclass did not intend (remember you’re working in a tem) causing undesirable behavior
- 29. Polymorphism ▪ When a single data type exhibits different behaviours during execution. ▪ Greek : Poly means “many”, morph means “form” ▪ Polymorphism means “existing in many forms” ▪ It is the other side of the same coin as inheritance ▪ Polymorphism is the reason why we want to have inheritance New Wave Analytica
- 30. Polymorphism ▪ Polymorphism allows for “pluggability” or “substitutability” ▪ Types that implement the same interface can substitute for one another ▪ Client code just sees one class, but the actual “concrete” type can be different in different cases. New Wave Analytica