What is Object Oriented System ? | Meaning & Characteristics of OOP

What is Object Oriented System ?

Object oriented systems represent data as objects. Other objects and users interact with these objects. Both the data and the information related to the executable file required for the data interpretation are comprised of object.

In case of object oriented system users focuses on the tasks not on the tools. The collaboration among the objects determines the behavior of the system. Collaboration is carried out by exchanging messages among the objects. Message sending is not similar to the function calling, as in this case the decision regarding what function is executed for servicing the message lies totally with the object.

A number of functions might execute a particular message. This election will be done based on the state of the object under consideration. Depending on the location of the objects taking part in the communication and the architecture of the system different types of message sending implementations are done.

Characteristics of Object Oriented Programming 

The Object-oriented paradigm (OOPs) has many features like :

1) Objects : 

Objects represent entities of the real world and are invoked at the runtime. They consist of data (properties) and operations (functions) to work on these data. The actual object created at the runtime is known as instance. According to programming jargon it is said that the Lassie object is an instance of the Dog class. The state of an object is defined by the set of values of the attributes. Behavior and state that is defined in the class of the object together construct the object.

2) Instance : 

Class instances are known as objects. The communication between the objects is considered in order to analyse a programming problem. At the time of execution interaction between the objects are done by exchanging of messages. The objects do not know the details regarding the code or data of the objects in order to carry out interaction with each other.

3) Classes : 

A new kind of static or compile time definition is class. It is a collection of data and the related functions or operations. From these classes, instances can be created at the runtime. A class is made up of objects of the same type. One can create multiple objects of a class once it has been created.

Class specifies the abstract properties of the objects along with their features which contain attributes, fields or properties. The operations or methods performed by the object are also defined within the class. It can be said in other words that class is a template or blueprint that specifies the characteristics of some entity. 

For example, the characteristics shared by all dogs are defined by the Dog class. It consists of properties such as breed and fur color and behaviors such as siting and barking ability. An object-oriented computer program gets modularity with the help of classes. The characteristics of the class must be defined in such a manner that a non programmer having knowledge about the problem should be able to recognize them. The code of the class should be also self-contained in nature. The methods and properties that make up a class are known as its members.

4) Inheritance : 

Inheritance is the process of declaring and defining a new class by extending features of existing class. The extension of features is done in terms of procedures or methods and data.

With the help of inheritance the objects belonging to one class are able to get the properties of the objects belonging to another class. With the help of inheritance, code can be reused by just adding the new features to an existing class without carrying out any modification. To do this a new class has to be derived from the existing class.

5) Data Abstraction : 

The process of abstraction hides all the low-level details and represents only those features that are essential. It is one of the important characteristics of an object using which the particular object can be differentiated from others. It helps in defining boundaries in a crisp manner with regard to the viewer's perspective. The prime objective of abstraction is to isolate the important aspects from the unimportant ones and suppress the later. Classes are also known as a list of abstract properties as they implement abstraction. It is possible to simplify the complex reality with the help of abstraction. This is done by designing classes that fits with the problem. Work can be also carried out at the most suitable level of inheritance based on the problem.

6) Encapsulation : 

Encapsulation is defined as the process of storing data and associated functions within a single class. This process is also known as information hiding and is complimentary to abstraction. In order to create the objects both data and code are defined using this process. There are many programmers who misinterpret that encapsulation means only data hiding. However, the process hides both code and data. Some of the code and data remain restricted as private member of the object while the others can be accessed directly as interface of the object. As a practice the data members are kept private and they are accessed using the member functions of the class which are declared in the public part. Only the functions declared within the class access the data. With the help of encapsulation it is possible to hide the operational details of a class from the objects. They can communicate via messages only. The concept of encapsulation and data abstraction has been shown in figure :

7) Polymorphism : 

The capability of taking multiple forms is known as polymorphism. Depending on the instance an operation may change its behavior. The behavior is based on the data type that has been used to perform the operation. In order to implement inheritance polymorphism is used extensively. Using polymorphism the programmer is able to treat the members of parent class and derived class in the same way. Polymorphism provides ability to the objects of different data types to respond to methods of same name based on some particular behavior based on a specific type. It becomes possible to abstractly use an operator like +, - or* in various situations.

8) Message Passing : 

By passing messages an object can ask some other object to invoke a method or simply exchange data with each other. It is also known as interfacing in some programming languages.