Java OOPs Concepts

Object-oriented programming’s OOP fundamental purpose is to put into effect real-global matters including gadgets, lessons, abstraction, inheritance, polymorphism, and so forth.

OOPs (Out of Order Procedures) (Object-Oriented Programming System)


A pen, chair, table, computer, watch, or other real-world entity is an object. Object-oriented programming (oop) is a programming technique or paradigm that makes use of lessons and gadgets to create a programme. It provides various notions that simplify software development and maintenance:

  • Object
  • Class
  • Inheritance
  • Polymorphism
  • Abstraction
  • Encapsulation

Aside from these notions, the following terminology are used in Object-Oriented design:

  • Coupling
  • Cohesion
  • Association
  • Aggregation
  • Composition
  • Object

An object is any entity that has kingdom and behavior. For example, a chair, pen, table, keyboard, bicycle, and so forth. It can be rational or bodily. An example of a category may be described as an item. An item holds an deal with and occupies memory space. Objects can communicate without knowing each other’s data or code details. Only the type of message accepted and the type of response returned by the objects are required.

Example: A dog is an item since it has properties such as colour, name, breed, and behaviours such as wagging the tail, barking, and eating.

The term “class” refers to a group of items. It’s a logical thing.

A class can alternatively be thought of as a blueprint for creating an individual object. Class does not take up any room.

Pillars Of OOP:



Inheritance occurs while one item inherits all the traits and movements of a discern item. It allows for code reuse. It’s utilised to achieve polymorphism at runtime.


Polymorphism takes place when a single venture is finished in more than one approaches. For example, to persuade a customer to think differently, draw a shape, triangle, rectangle, or other object.

To create polymorphism in java, we rent method overloading and technique overriding. Every other example is to say something; as an example, a cat meows, a canine barks woofs, and so forth.


Abstraction is the technique of hiding inner details while displaying capability. We do not know the internal processes of a telephone name, for instance. To gain abstraction in java, we rent summary classes and interfaces.


Encapsulation is the system of becoming a member of (or wrapping) code and records into a unmarried entity. A capsule, as an instance, is coated in various tablets.

Encapsulation is demonstrated by a Java class. Because all data members are private, the Java bean is the fully contained class.


Another class’s knowledge, information, or dependency is referred to as coupling. It occurs when classes become aware of one another. There is strong coupling when a class contains the details information of another class. To display the visibility level of a class, method, or field in Java, we utilise the private, protected, and public modifiers. Because there is no concrete implementation, you can utilise interfaces for the weaker coupling.



The level of cohesion of a component that performs a single well-defined task is referred to as cohesion. A very coherent approach is used to complete a single well-defined task. The assignment will be divided into several segments using the weakly cohesive method. Because it contains I/O-related classes and interfaces, the package is quite coherent. The java.util package, on the other hand, is a disjointed collection of classes and interfaces.


The relationship between the things is represented through association. One item can be linked to a single or several objects. There are four different types of object associations:

  • One to One
  • One to Many
  • Many to One, and
  • Many to Many

Let’s look at real-life instances to better comprehend the relationship. One country, for example, can have just one prime minister (one to one), whereas a prime minister can have many ministers (one to many). Furthermore, several MPs can have the same prime minister (many to one), and numerous ministers can have multiple departments (many to many).

Unidirectional or bidirectional association is possible.


Aggregation is a method of attaining Association. Aggregation refers to a relationship in which one object’s state includes other items. It represents a shaky connection between objects. In Java, it’s known as a has-a relationship. The is-a relationship, for example, is represented by inheritance. It’s another way to recycle items.


Association can also be achieved through composition. The composition represents the relationship in which one object’s state includes other things. The enclosing item and the dependent object have a strong relationship. It is the situation in which the contained objects do not have their own existence. When you delete the parent object, all of the child objects are also erased.

Read Also: What is Java Proramming? Definition, Meaning

Advantage of OOPs over Procedure-oriented programming language

  • OOPs makes development and maintenance easier, whereas procedure-oriented programming languages are difficult to maintain as project sizes expand.
  • Data concealing is provided by OOPs, whereas global data can be accessed from anywhere in a procedure-oriented programming language.

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