OOPs concept

  • OOP stands for Object Oriented programming
  • Before OOPs there were procedural programming where it was all about the functions and variables written into a single file. Where variables stored data and functions performed operations on that data.
  • After oops concept came up we divided the functions and variables into logical groups called class and started calling functions and variables as methods and properties respectively.

4 pillers of OOPs

  • Encapsulation
  • Abstraction
  • Inheritance
  • Polymorphism


  • Encapsulation is the idea of bundling data and methods that work on that data within one unit. Eg class in java
  • Note : Lesser that number of arguments to the methods, better the code.
    ” The best functions are those with no parameters!” – Robert C Martin


  • Looking at something without being concerned about the inner details or mechanics.
  • Example : While Driving a car, person need not be concerned about what happens internally when you press a accelerator or a break but what he needs to know is which function to call to actually perform those operations.


  • Inheritance is a mechanism in which one class acquires the property of another class.
  • For example, a child inherits the traits of his/her parents. With inheritance, we can reuse the fields and methods of the existing class.
  • Hence, inheritance facilitates Reusability and is an important concept of OOPs

Polymorphism (Many forms)

  • Polymorphism refers to a programming language’s ability to process objects differently depending on their data type or class.
  • Polymorphism allows you to define one interface and have multiple implementations
  • There are two types of polymorphism in java
    • Compile time polymorphism
    • Run time polymorphism

Others Benefits of java : Robust

  • One of the major advantages of Java over C++ is that it prevents memory leaks.
  • Java manages memory on its own and does garbage collection automatically.
  • Bad memory management in C++ is a big source of errors in programs.

Others Benefits of java : Secure

  • Java code runs inside the JVM.
  • This creates a sandbox that makes it hard for Java code to do evil things to the computer it is running on.

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