In this chapter we will familiarize ourselves with the principles of objectoriented programming. The object oriented paradigm allows us to organise software as a collection of objects that consist of both dataattributes and behaviours. For an experienced object oriented programmer this is probably too basic of a book, but for a student or someone new to programming, the information here is clear and explanatory. Oop includes classes, objects, overloading, encapsulation, data hiding, and inheritance. If class rectangle is derived from class quadrilateral, then a rectangle object is a more specific version of a quadrilateral.
Lets consider several other examples of polymorphism. A program is a set of objects telling each other what to do by sending messages. Polymorphism, encapsulation, data abstraction and inheritance in. With polymorphism, each subclass may have its own way of implementing the function. All objects of a specific type can receive the same messages. Object oriented programming popularly known as oops and it is used in many other programming languages. In the following example, targeted at the java runtime, well see how an.
Jobs programming and related technical career opportunities. As we have seen in the above example that we have defined the method sound and have the multiple implementations of it in the different2. These three concepts are sometimes considered as the building block of object oriented programming oop. Encapsulation encapsulation is a construct in oop that allows both the object and the operations performed on that object methods to be bundled into a class and restricts access to the methods of the class. Object oriented programming oop is a programming paradigm based on the concept of objects, which can contain data, in the form of fields often known as attributes or properties, and code, in the form of procedures often known as methods. Object oriented programming oop is a programming approach based on objects and classes. In typical implementations, each class contains what is called a virtual table a table of functions that implement the polymorphic part of the class interfaceand each object contains a pointer to the vtable of its class, which is then consulted whenever a polymorphic method is called. Object oriented programming is a method of programming where programmers define the type of data as well the operations that the data can perform. For example, we treat duck as an animal and not just as a duck.
With abstraction, you can hide the internal workings of an object and only show the features the user needs to know about. Throughout the text we emphasize careful coverage of java language features, introductory programming concepts, and object oriented design principles. For example, a person is an object which has certain properties such as height, gender, age, etc. The objectoriented programming course is designed to provide a comprehensive study of the c programming language. Java, like many other object oriented programming languages, allows you to implement multiple methods within the same class that use the same name but a different set of parameters. The objectoriented thought process developers library. Object oriented programmingpolymorphism wikibooks, open. Other languages require inheritance or the formal definition and implementation of interfaces for polymorphism to work. Method overloading in java this is an example of compile time or static polymorphism 2. Polymorphism is an important mechanism used in oo programming that allows.
Object oriented design is another way of looking at the design process, which views a program from the standpoint of data rather than tasks. Its the head first design pattern which taught me how to write flexible code using inheritance and polymorphism. Get a grounding in polymorphism and other fundamental aspects of object oriented program design and implementation, and learn a subset of design patterns that any practicing java professional simply must know in. The third edition retains many of the features of the.
Those are features of classbased programming languages, which are the most popular object oriented programming languages. In typical implementations, each class contains what is called a virtual table a table of functions that implement the polymorphic part of the class interfaceand each object contains a pointer to the vtable of its class, which. Each object has its own memory made up by other objects. An object oriented principles can guide you to build flexible and good code practice. For example, when you login to your amazon account online, you enter your. Polymorphism can also be explained as the ability to perform a single action, in many ways, across multiple objects. Object oriented programming in java java oops concepts. The best way to learn object oriented programming is following both head first java and head first object oriented analysis and design, followed by head first design pattern.
Because the functionality associated with this design process is often incorporated into highlevel programming languages, we need to understand this design process before looking at specific highlevel languages. Java, like many other object oriented programming languages, allows you to implement multiple methods within the same class that use the same name but a different set of. In other words, polymorphism allows you define one interface and have multiple implementations. Any java object that can pass more than one isa test is considered to be polymorphic. Object oriented programming is a programming style which is associated with the concepts like class, object, inheritance, encapsulation, abstraction, polymorphism. As you can see from the example above, makenoise prints different result on the same animal reference. Objects, classes, encapsulation, polymorphism, and more. At runtime it decides the type of object and calls the corresponding method. A study of objectoriented programming by explaining and demonstrating. You will also see the demonstration of source code implementation for each topic. Java, like many other objectoriented programming languages, allows you to implement multiple methods within the same class that use the same name but a different set of parameters. Over time, when you sit down to solve the next problem, youll naturally try to figure out how to avoid the stuff from the last code. What are good books to learn objectoriented programming.
Inheritance in traditional object oriented languages offers three features in one. We will explain in details the principles of cohesion and coupling. A realworld example of inheritance is a mother and child. Polymorphism is the capability of a method to do different things based on the object that it is acting upon. Object oriented programming languages offer subtype polymorphism using subclassing also known as inheritance. In java, all java objects are polymorphic since any object will pass the. For example, lets say we have a class animal that has a method animalsound, here we cannot give implementation to this method as we do not know which animal class would extend animal class. Polymorphism is one of the most important concepts in object oriented programming. So, for example, when the move function is called in an object of the horse class, the function might respond by displaying trotting on the screen. What is inheritance in java with example object oriented.
Method overriding in java this is an example of runtime time or dynamic polymorphism 3. We now consider several additional examples of polymorphism. This chapter is an excerpt from the book, java for programmers, authored by paul and harvey. Procedural programming is about writing procedures or methods that perform operations on the data, while object oriented programming is about creating objects that contain both data and methods. Objectoriented programming wikibooks, open books for an.
Visual basic object oriented programming encapsulation next. The most common use of polymorphism in oop occurs when a parent class reference is used to refer to a child class object. Moreover, it must use the fundamental object oriented principles of abstraction, inheritance, polymorphism, and encapsulation. We now continue our study of object oriented programming by explaining and demonstrating polymorphism with inheritance hierarchies. Encapsulation, inheritance and polymorphism in object.
Enterprise private selfhosted questions and answers for your enterprise. Lets see how go measures up against the pillars of object oriented programming. We will briefly outline object oriented modeling and. Which sound method will be called is determined at runtime so the example we gave above is a runtime polymorphism example. Encapsulation, inheritance, polymorphism, abstraction. Visual basic object oriented programming inheritance. Polymorphism is a big word that you can break down into poly which means many and morphism which means form. Some concepts are abstraction, encapsulation, inheritance, and polymorphism. Object oriented programming oop is a programming paradigm organized around objects rather than actions, and data rather than logic. For example, we can get the value of the title with book. Java, java, java computer science computer science.
An object is a thing that we interact with, it has properties and methods. Objectoriented programming without inheritance yourbasic go. Polymorphism is the ability of one object to be treated and used like another object. The book class as shown in the class diagram contains the following members. Now, lets see the reallife characteristics of the four main oop concepts in java. This means we can use the same method across different objects, using different implementations. Object oriented programming has several advantages over procedural programming. Keep in mind that becoming expert in oo programming is largely achieved through writing and reading a lot of code. More specifically, it is the ability to redefine methods for derived classes.
A cursor may take different forms like an arrow, a line, cross, or other shapes depending on the behavior of the user or the program mode. Introduction 2 pure object oriented languages five rules source. As java being the most soughtafter skill, we will talk about object. Finally, the book concludes with material on important features of java that are not object oriented. Polymorphism is the capability of a single object to take on multiple forms. Following this is an indepth discussion on inheritance and polymorphism. It stresses the strengths of c, which provide students with the means of writing efficient, maintainable and portable code. In java it means that the method that gets called at runtime when the code is run depends on the type of the object at runtime this is simliar to a toddler toy that has pictures of animals and when a handle is pulled. Object oriented programming with real world example. Simple example for it is,we are turn on the phone by one button at the same time we can turn off the phone by the same button. The goals of polymorphism in object oriented programming is to enforce simplicity, making codes more extendable and easily maintaining applications. In a nutshell, object oriented programming is a simple engineering advance to build software systems which models. That is called method overloading and represents a static form of polymorphism. Objectoriented programming lecture notes download b.1236 986 226 792 825 148 802 731 1452 245 597 1156 1089 1332 380 4 618 727 341 388 766 1376 1511 29 1303 1357 1428 1447 37 1453 152 1055 21 1440 961 159 543 1179 1255 1030 1262 1409 465