Basic Concepts of OOPs (Object Oriented Programming in Java)
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This document provides an overview of basic object-oriented programming (OOP) concepts including objects, classes, inheritance, polymorphism, encapsulation, and data abstraction. It defines objects as entities with both data (characteristics) and behavior (operations). Classes are blueprints that are used to create objects. Inheritance allows objects to inherit properties from parent classes. Polymorphism allows code to take different forms. Encapsulation wraps data and functions into classes, hiding information. Data abstraction focuses on important descriptions without details.
Basic Concepts of OOPs (Object Oriented Programming in Java)
- 1. BASIC CONCEPTS OF OOPs Presented by: Michelle Anne Meralpis
- 2. JAVA • Java – a high-level programming language • Same with C, FORTRAN, Smalltalk, Perl • Lets you write special programs called Applets • Java is called as an Object-Oriented Programming Language
- 3. What is OOP? • Software Development Technique • Effective use of programmer productivity • Way of creating large scale systems • Approaching 100% solution
- 4. Basic Concepts of OOPs • Object • Class • Inheritance • Polymorphism • Encapsulation • Data Abstraction
- 5. Object • A person, place or concepts • Composed of characteristics (data) and behavior (operation)
- 6. Example:
- 7. Class • A blueprint or prototype from which objects are created • A collection of objects of similar type
- 9. Example:
- 10. Inheritance • The process by which objects of one class can get properties of objects of another class.
- 11. Polymorphism • The ability to take more than one form • Allows us to write generic, reusable code more easily
- 12. Example:
- 13. Encapsulation • Wrapping of data and functions into a single unit (i.e. class) • Information hiding
- 14. Data Abstraction • Refers to the act of representing important description without including the background details or explanations
- 15. Creating Objects Point originOne = new Point(23,94); Rectangle rectOne = new Rectangle(originOne, 100, 200); Rectangle rectTwo = new Rectangle(50, 100); Each of these statements has three parts: 1. Declaration – the code set in bold are all variable declarations that associate a variable name with an object type. 2. Instantiation – the new keyword is a Java operator that creates the object. 3. Initialization: The new operator is followed by a call to a constructor, which initializes the new object.
- 16. Declaring Object Reference • Previously, you learned that to declare a variable, you write: type name; • You can also declare a reference variable on its own line. For example: Point originOne;
- 17. Instantiating a Class • The new operator returns a reference to the object it created. This reference is usually assigned to a variable of the appropriate type, like: Point originOne = new Point(23, 94); • It can also be used directly in an expression. For example: int height = new Rectangle().height;
- 18. Initializing an Object • Here's the code for the Point class: public class Point { public int x = 0; public int y = 0; //constructor public Point(int a, int b) { x = a; y = b; } }
- 19. Initializing an Object (2) Point originOne = new Point(23, 94); • The result of executing this statement can be illustrated in the next figure:
- 20. Calling an Object's Methods • Append the method’s simple name to the object reference using intervening dot operator (.) • Provide arguments to the method within enclosing parenthesis () objectReference.methodName(argumentList); Or objectReference.methodName();
- 21. Calling an Object's Methods (2) new Rectangle(100, 50).getArea() • As shown, you can use the dot notation to invoke the new Rectangle’s getArea() method to compute the area of the new rectangle.