Java OOPs Concepts

In this tutorial, we will see the basic object-oriented programming concepts.

Introduction

Object-oriented programming (OOP) is a computer programming model that organizes software design around data, or objects, rather than functions and logic.

There are many opps concepts but here we will see the most important 4. I.e Abstraction, Encapsulation, Inheritance and Polymorphism.

Java OOPs Concepts

1. Abstraction

Hiding internal implementation and just hightailing the functionalities offered is known as abstraction.

Example: ATM functions are a practical example of abstraction. They just highlight the functionality i.e. withdrawing money, checking balance or printing the mini statement. It does not show the internal implementation of those functions.

Method in a Java class is an example of Abstraction.

2. Encapsulation

The process of grouping the data members and corresponding methods in a single unit is called encapsulation.

Every Java class is an example of encapsulation. Java bean is the fully encapsulated class because all the data members are private here.

Example:

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public class Student {
	
  private int id;
  
  private String name;
  
  public int getId() {
    return id;
  }
  
  public void setId(int id) {
    this.id = id;
  }
  
  public String getName() {
    return name;
  }
  
  public void setName(String name) {
    this.name = name;
  }

}

In the above code, the data members like id, name and corresponding methods such as setId(), getId etc. are grouped together in a java class Student. So Java class is a good example of Encapsulation.

3. Inheritance

When a child object acquires all the properties and behaviours of a parent object, it is known as inheritance. It provides code re-usability. It is an IS-A relationship.

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public class Animal {
	
  private String name;
  
  public void run() {
  
  }
  
  public void feed() {
  
  }

}

class Dog extends Animal{
	
  private String breed;
  
  public void bark() {
  
  }
}

In the above example, the Animal class is a Parent class and the Dog class is a child class.

The animal can have a name, it can run.

We have created a child class Dog which extends the Animal class. That means the Dog class inherits the properties and behaviours of the parent class Animal.

A dog can have a name, it can run and in addition, it can have its own property like breed and behaviours like bark().

4. Polymorphism

If one task is performed in different ways, it is known as polymorphism.

The word poly means many and morphs means forms or ways.

In Java, we use method overloading and method overriding to achieve polymorphism.

There are two types of polymorphism in Java:

1. Compile-time Polymorphism
2. Runtime Polymorphism.

Compile-time polymorphism can be achieved by overloading the static method. While Runtime Polymorphism can be achieved by overriding the parent class method in the child class.

Conclusion

Abstraction, Encapsulation, Inheritance and Polymorphism are the most important oops concepts in Java.

1. In Abstraction we hide the internal implementation and highlight the functionalities offered. Ex. method in Java

2. Encapsulation is the process of grouping data members and corresponding methods in a single unit. Ex. Java Class

3. In inheritance, a child class inherits all the properties and behaviour of the parent class. It can be done by extending the parent class. Ex. class Dog extends Animal{...}
4. Doing one task in many ways is called polymorphism. In Java, polymorphism can be done using method overloading and method overriding.

Please write your thoughts in the comment section below.