Introduction to OOP Questions and Answers
OOP (Object-oriented Programming) is a programming paradigm that contains objects and fields to hold the data and methods to implement business logic. Each and every object can interact with each other based on their access level modifiers. The object-oriented paradigm is based on the classes and objects where objects are the instances of the classes and can be created in different ways. There are different object-oriented programming languages such as C++, C#, PHP, Ruby, Java, Python, etc. The main features of Object-oriented Programming techniques are Abstraction, Encapsulation, Inheritance, and Polymorphism. Most of the dynamic programming languages are based on OOPs principles.
Now, if you are looking for a job which is related to OOP then you need to prepare for the 2020 OOP Interview Questions. It is true that every interview is different as per the different job profiles but still to clear the interview you need to have a good and clear knowledge of OOP. Here, we have prepared the important OOP Interview Questions and Answers which will help you get success in your interview. These OOP Interview questions are divided into parts are as follows:
Below are the 10 important 2020 OOP Interview Questions and Answers:
Part 1 – OOP Interview Questions (Basic)
This first part covers basic OOP Interview Questions and Answers
1. What are the core concepts of OOP?
Answer:
The core concepts of OOP are Abstraction, Encapsulation, Inheritance, and Polymorphism. Abstraction is the process of concealing the complex logic by defining the code in a separate private method by hiding its implementation. Whatever the functionality needed to use can be called by using its method identifier to get the result.
The concept of encapsulation is nothing but a Class that is used to hide the fields that hold data and the methods to perform the functions which can be accessed based on access modifier. Polymorphism is the process of defining the same method multiple times to utilize based on data types or arguments. There are two types of polymorphism which are called runtime polymorphism and compile-time polymorphism.
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2. What is a Class in OOP?
Answer:
A Class in Object-oriented Programming is ideally called as a template or a blueprint of an object. An object of its class type will have the same properties as defined in the implementation of Class. An object will always be a specific instance of a class. A Class can have different subclasses and superclasses. A class can be a child class or parent class depends on its declaration. A subclass can have all the properties that its superclass has whereas the superclass cannot have the properties of the subclass. A class can be extended by another class and it will be called as a parent class.
Let us move to the next OOP Interview Questions And Answer.
3. What is a constructor in OOP?
Answer:
A constructor is a method used to invoke the object creation process by initializing the state of the object. The name of the constructor should be the name of the class ideally and may vary depends on the type of programming language. A constructor must not have any return type.
4. What is the Destructor in OOP?
Answer:
This is the most common OOP Interview Questions which is asked in an interview A Destructor is a method which is invoked at the time of the object is destroyed or when its’ scope is about to end. The method will be called explicitly or implicitly based on the programming language used. In C++, destructor needs to be called whereas in Java, it is not needed and it will be handled by garbage collection mechanism.
5. What is an Abstract class in OOP?
Answer:
An abstract class is used to define at least one abstract method but an object cannot be created from it. Classes created using abstract classes are called derived classes. An abstract class will not contain implementation code in its base class. If an abstract class is forced to instantiate an object out of it, a compilation error will be thrown.
Part 2 –OOP Interview Questions (Advanced)
Let us now have a look at the advanced OOP Interview Questions.
6. What is multiple-inheritance in OOP?
Answer:
Multiple inheritances are the process of extending the behaviors of multiple classes by a single class. It creates an ambiguous situation at the time of runtime to decide about which class’ behavior has to be executed. C++ supports multiple inheritances whereas Java doesn’t support. The ambiguity and complex issues create a diamond problem which is defined as to extend which parent class upon extending multiple classes.
7. What is static and dynamic binding in OOP?
Answer:
Static binding is also called as early binding which happens at compile time whereas Dynamic binding is called late binding which happens at the time of run time. Example of static binding is method overloading and dynamic binding is method overriding. The process of binding for static, final and private methods will always be done at compile time whereas the overriding is done at runtime. The process of binding overloaded methods is called static whereas the binding of overridden methods is called dynamic.
Let us move to the next OOP Interview Questions And Answer.
8. What is operator overloading in OOP?
Answer:
Operator overloading is sometimes called as ad-hoc polymorphism which is defined as different operators will have different mechanism based on the placement of operators and the arguments. In operator overloading, the semantics of the programming language is redefined which is not usually recommended. In case of Java programming language, it was decided by the creators not to use this feature as Java is a production language mostly.
9. What is exception handling in OOP?
Answer:
This is the frequently asked OOP Interview Questions which is asked in an interview. Exception handling is the feature available in most of the object-oriented programming languages which are defined as the process of handling the exceptions during the execution of program flow. The flow of execution should be altered based on the outcome of the exception of aroused. The general blocks of exception handling include try, catch and throw for the most of programming languages like C++, Java etc. In try block the code needs to be executed will be placed and catch block will handle the exception and throw block will return the type of exception and error if it can’t be handled. This is the safest way of handling applications to safeguard the flow of the working application
10. What are the benefits of OOPS techniques?
Answer:
The main benefits of the OOPS concepts are modularity, extensibility, simplicity, reusability, maintainability, modifiability etc. The complexity of the programming can be reduced and the coding structure can be made clear. The different complex functionalities can be decoupled using different classes and implementation methods around the application. The reusability feature provides minor changes in the code whenever needed, which provides the adaptability for the code changes or functionality changes.
The objects of the different classes can be reused in different implementation classes to use its features completely. The maintenance process becomes easier if the code is maintained in an organised way.
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