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Introduction.ppt JAVA SCRIPT PROGRAMMING AND
- 1. 1 INTRODUCTION TO OOP Objective: •Know the difference between functional programmin and OOP • Know basic terminology in OOP • Know the importance of OOP • Know four design principles of OOP • Know OOP programming languages
- 2. Programming Paradigm A programming paradigm is a style, or “way,” of programming
- 3. Types of Programming Paradigm Imperative: Programming with an explicit sequence of commands that update state. Declarative: Programming by specifying the result you want, not how to get it. Object-Oriented: Programming by defining objects that send messages to each other. Objects have their own internal (encapsulated) state and public interfaces.
- 4. Types of Programming Paradigm… Object orientation can be: Class-based: Objects get state and behavior based on membership in a class. Prototype-based: Objects get behavior from a prototype object. Structured: Programming with clean, goto-free, nested control structures. Procedural: Imperative programming with procedure calls.
- 5. Types of Programming Paradigm.. Event-Driven: Programming with emitters and listeners of asynchronous actions. Flow-Driven: Programming processes communicating with each other over predefined channels. Functional (Applicative): Programming with function calls that avoid any global state. Function-Level (Combinator): Programming with no variables at all.
- 6. Types of Programming Paradigm.. Logic (Rule-based): Programming by specifying a set of facts and rules. An engine infers the answers to questions. Constraint: Programming by specifying a set of constraints. An engine finds the values that meet the constraints. Aspect-Oriented: Programming cross- cutting concerns applied transparently.
- 7. 7 STRUCTURED vs. OO PROGRAMMING STRUCTURED PROGRAMMING: MAIN PROGRAM FUNCTION 3 FUNCTION 2 GLOBAL DATA FUNCTION 5 FUNCTION 4 FUNCTION 1
- 8. 8 Structured Programming Using function Function & program is divided into modules Every module has its own data and function which can be called by other modules.
- 9. 9 OBJECT ORIENTED PROGRAMMING Object 1 Object 2 Data Function Data Function Object 3 Data Function
- 10. 10 OBJECT ORIENTED PROGRAMMING •Objects have both data and methods • Objects of the same class have the same data elements and methods • Objects send and receive messages to invoke actions Key idea in object-oriented: The real world can be accurately described as a collection of objects that interact.
- 11. 11 Basic terminology Basic terminology •object - usually a person, place or thing (a noun) •method - an action performed by an object (a verb) •attribute - description of objects in a class •class - a category of similar objects (such as automobiles) - does not hold any values of the object’s attributes
- 12. 12 Example for attributes and methods Attributes: manufacturer’s name model name year made color number of doors size of engine etc. Methods: Define data items (specify manufacturer’s name, model, year, etc.) Change a data item (color, engine, etc.) Display data items Calculate cost etc.
- 13. 13 Why OOP? • Save development time (and cost) by reusing code –once an object class is created it can be used in other applications • Easier debugging –classes can be tested independently –reused objects have already been tested
- 14. 14 Design Principles of OOP Four main design principles of Object- Oriented Programming(OOP): • Encapsulation • Abstraction • Polymorphism • Inheritance
- 15. 15 Encapsulation •Also known as data hiding •Only object’s methods can modify information in the object. Analogy: • ATM machine can only update accounts of one person or object only.
- 16. 16 Abstraction Focus only on the important facts about the problem at hand to design, produce, and describe so that it can be easily used without knowing the details of how it works. Analogy: When you drive a car, you don’t have to know how the gasoline and air are mixed and ignited. Instead you only have to know how to use the controls. Draw map
- 17. 17 Polymorphism •the same word or phrase can mean different things in different contexts Analogy: •In English, bank can mean side of a river or a place to put money •move -
- 18. 18 Function Overloading The operation of one function depends on the argument passed to it. Example: Fly(), Fly(low), Fly(150)
- 19. 19 Inheritance • Inheritance—a way of organizing classes • Term comes from inheritance of traits like eye color, hair color, and so on. • Classes with properties in common can be grouped so that their common properties are only defined once. • Superclass – inherit its attributes & methods to the subclass(es). • Subclass – can inherit all its superclass attributes & methods besides having its own unique attributes & methods.
- 20. 20 An Inheritance Hierarchy Vehicle Automobile Motorcycle Bus Sedan Sports Car School Bus Luxury Bus What properties does each vehicle inherit from the types of vehicles above it in the diagram? Superclass Subclasses
- 21. 21 Object-Oriented Programming Languages Pure OO Languages Smalltalk, Eiffel, Actor, Java Hybrid OO Languages C++, Objective-C, Object-Pascal