Chapter 6 OOP (Revision)
Download as PPT, PDF2 likes2,287 views
1) Object-oriented programming (OOP) uses classes and objects to organize code and data to make it more modular and reusable. Many popular languages like Java, C++, and C# use OOP. 2) A class defines the data (properties) and behavior (methods) of an object. Constructors are used to create objects from classes. 3) To access data and methods of an object, it must first be instantiated by using the new keyword followed by the class name, then its methods and properties can be called.
![Constructors (2) How to construct objects? Usually, we have many classes in a projects. So the student class will be created in other classes. To construct objects from student class: public class TestStudent { public static void main(String[] args){ Student stu; //To construct an object stu = new Student(); System.out.println(stu.toString()); } }](https://image.slidesharecdn.com/chapter6-ooprevision-090928103923-phpapp01/85/Chapter-6-OOP-Revision-7-320.jpg)
![Access Object’s Data and Methods To access method: public class TestStudent { public static void main(String[] args){ Student stu; //To construct an object stu = new Student(“123”,”Veasna”); System.out.println( stu.toString() ); } } To access data: Usually, We don’t access the data. If you like, you can do like : stu.id = 123 in case id is not private .](https://image.slidesharecdn.com/chapter6-ooprevision-090928103923-phpapp01/85/Chapter-6-OOP-Revision-8-320.jpg)
Chapter 6 OOP (Revision)
- 1. Object-Oriented Programming with Java Oum Saokosal , Head of IT Department National Polytechnic Institute of Cambodia Tel: (855)-12-417214 E-mail: [email protected]
- 2. Chapter 6 Objects and Classes (Revision) OOP Classes Objects Constructors Accessing Object’s Data and Methods
- 3. Object-Oriented Programming Why learning OOP? Java is a pure OOP OOP provides more flexibility, modularity, clarity, reusability Other Programming: C++, C#, VB .NET, ActionScript 3.0, Ruby etc. also use OOP. 3 concepts of OOP: Class Encapsulation Class Inheritance Polymorphism
- 4. Classes (1) What is a class? A class is similar to a template, blueprint or symbol (in Adobe Flash). A class creates many objects. Class Objects
- 5. Classes (2) In a class, there are : Data Fields (Properties) Behavior: Constructors Methods public class Student { private int id, String name; public Student(){} public Student (int inputID, String inputName){ this.id = inputID; this.name = inputName; } public String toString(){ return id + name; } }
- 6. Constructors (1) What is constructor? A constructor is to construct (create) objects from a class. public class Student { private int id, String name; public Student(){} public Student (int inputID,String inputName){ this.id = inputID; this.name = inputName; } public String toString(){ return id + name; } }
- 7. Constructors (2) How to construct objects? Usually, we have many classes in a projects. So the student class will be created in other classes. To construct objects from student class: public class TestStudent { public static void main(String[] args){ Student stu; //To construct an object stu = new Student(); System.out.println(stu.toString()); } }
- 8. Access Object’s Data and Methods To access method: public class TestStudent { public static void main(String[] args){ Student stu; //To construct an object stu = new Student(“123”,”Veasna”); System.out.println( stu.toString() ); } } To access data: Usually, We don’t access the data. If you like, you can do like : stu.id = 123 in case id is not private .