Object Oriented Programming (OOPs) for JAVA Interviews [Free Download]

Object Oriented Programming (OOP) is a form of programming that focuses on objects. Unlike traditional programming, which is a model of the world, OOP emphasizes the creation of objects that can be used to create and manipulate data.

Objects, or instances of a class, are defined by their characteristics, attributes, and methods. Objects also inherit attributes, methods, and behaviors from their parent classes. Using inheritance in OOP makes it easier to create new objects. However, this also means that a new object cannot change its parent class, but can instead inherit its characteristics.

In OOP, objects are also used to communicate with each other. They can exchange data and messages through a well-defined interface called a message. These messages can also be read by the other object. In addition, objects can exchange data through their instance variables. This allows the program to become more complex and interactive.

Objects can also be used to control the environment of a program. They can act on messages and other information, and can also be used to establish business rules. The overall goal of Object-Oriented Programming is to improve the development workflow and increase code readability. A large program with thousands of lines of code can be challenging to debug. It is a good idea to use a clean, concise code to prevent erroneous behavior.

Object-oriented programming requires a closer investigation of data than conventional programming. During the development process, a developer can decide which data to expose and which to hide. This enables programmers to reuse common functionality while maintaining a separate hierarchy. It can also be beneficial during debugging.

In OOP, a class defines the data, description, and logic sequence of an object. It is like a blueprint for a new object. It can contain the data, methods, and logic sequences that define the behaviors of an object. In addition, the class can implement multiple interfaces. Some of these interfaces are public, and others are private. The public interface is accessible from outside the class, while the private interface is only available to the object itself and its child classes.

In OOP, encapsulation is a method of hiding internal information of a class from the external world. The information is encapsulated in a protected section of the class. This adds security and simplifies program maintenance. Moreover, encapsulating data reduces the risk of errors and makes it easier to collaborate with other developers.

Another method of encapsulation is abstraction. This is an extension of encapsulation that allows an object to acquire traits from its parents. It is commonly incorporated in pure functional programming and is considered a design pattern.

A method is a specific logic sequence that describes the behaviors of an object. It may be defined in a class, or it may be defined in the template of a class. It is also important to note that methods are often referred to as functions.

Object-oriented programming has gained popularity and recognition in the 90s with the introduction of Java. A large number of existing languages have added OOP features. It is important to note that some of the features of OOP can complicate the maintainability of your code.

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