Abstraction In Java Interview Questions
Exploring the Concept of Abstraction in Java: Frequently Asked Questions for Interviews
Abstraction in Java is a process of hiding the implementation details and exposing only the necessary information or functionality to the user. It helps in creating a simplified and more manageable code by only showing the essential features and details. This concept is achieved through the use of abstract classes, interfaces, and abstract methods. By using abstraction, developers can focus on solving the problem at hand without worrying about the inner workings of complex systems, making the code more flexible and reusable. Abstraction also helps in achieving better security as sensitive data can be hidden from the user.
To Download Our Brochure: https://www.justacademy.co/download-brochure-for-free
Message us for more information: +91 9987184296
points
1 - What is Abstraction in Java?
Abstraction is a fundamental concept in object-oriented programming that allows for the representation of complex real-world entities in a simplified and generalized manner. In Java, abstraction is the process of hiding the implementation details of an object and exposing only its essential features and functionality to the user.
2) Why is Abstraction important in Java?
Abstraction helps in reducing complexity by focusing on the essential aspects of an object. It also enables software developers to create modular, reusable, and maintainable code. By hiding implementation details, abstraction helps in creating a high-level view of an object, making it easier to understand and work with.
3) How is Abstraction implemented in Java?
In Java, abstraction is implemented using abstract classes and interfaces. Abstract classes are classes that cannot be instantiated and provide a template for its subclasses to follow. Interfaces, on the other hand, are collections of abstract methods that a class must implement in order to use its functionality.
4) What is the difference between abstract classes and interfaces?
One key difference between abstract classes and interfaces is that abstract classes can have both abstract and non-abstract methods, while interfaces can only have abstract methods. Additionally, a class can only extend one abstract class, but it can implement multiple interfaces.
5) What is an abstract method?
An abstract method is a method in an abstract class or interface that does not have any implementation. It is declared in the parent class or interface and must be implemented by its subclasses or implementing classes. Abstract methods are used to enforce a certain behavior in its subclasses or implementing classes.
6) Can we create an object of an abstract class or interface?
No, we cannot create an object of an abstract class or an interface as they are incomplete classes and do not have a complete implementation of all their methods. However, we can create objects of subclasses of an abstract class or classes that implement an interface.
7) Can abstract classes have constructors?
Yes, abstract classes can have constructors, but they cannot be used to create objects. Constructors in abstract classes are used to initialize common variables or perform other functions needed by its subclasses.
8) What is the purpose of an abstract class?
The purpose of an abstract class is to provide a common template to its subclasses, which can then implement their own unique behavior while inheriting the common behavior of the abstract class. It also helps in reducing code duplication and promoting code reusability.
To Download Our Brochure: Click Here
Message us for more information: +91 9987184296
9) What is the purpose of an interface?
The purpose of an interface is to define a set of methods that a class must implement to use its functionality. It helps in achieving abstraction and loose coupling between different components of a system. Interfaces also promote code reusability and enhance the scalability of a system.
10) Can an abstract class extend another abstract class?
Yes, an abstract class can extend another abstract class. This allows for the creation of a hierarchical inheritance structure, where more specific abstract classes inherit from a more general abstract class.
11) Can we extend an interface in Java?
No, we cannot extend an interface in Java. However, an interface can extend other interfaces, allowing for the creation of a hierarchy of interfaces.
12) What is the use of the keyword ‘implements’ in Java?
The ‘implements’ keyword is used to indicate that a class is implementing an interface. It is used in the class declaration and is followed by the name of the interface being implemented.
13) Can an abstract class implement an interface?
Yes, an abstract class can implement an interface. This allows for the combination of abstract classes and interfaces to create a comprehensive and modular design structure in a program.
14) What is the purpose of the ‘abstract’ keyword in Java?
The ‘abstract’ keyword is used to define an abstract class or method in Java. It indicates that the class or method is not complete and needs to be implemented by its subclasses or implementing classes.
15) Can an abstract class have non-abstract methods?
Yes, an abstract class can have non-abstract methods, also known as concrete methods. These methods can have implementations and can be inherited by its subclasses.
16) What is the main difference between abstraction and encapsulation?
The main difference between abstraction and encapsulation is that abstraction focuses on the essential features and behavior of an object, while encapsulation focuses on the hiding of implementation details.
17) Can abstract classes or interfaces have private methods?
No, abstract classes and interfaces do not allow for the creation of private methods. All methods in an interface are implicitly public, and abstract methods in an abstract class must also be declared as public.
18) What is the relationship between inheritance and abstraction?
Abstraction is often used in conjunction with inheritance to create a hierarchial structure of classes. Inheritance allows for the sharing of common behavior and features between classes, while abstraction allows for the hiding of certain implementation details.
19) How does abstraction promote code reusability?
Abstraction promotes code reusability by providing a common template for subclasses or implementing classes to follow. This allows for the reuse of code and promotes a modular and flexible design structure.
20) Is it possible to achieve 100% abstraction in Java?
No, it is not possible to achieve 100% abstraction in Java. Some level of implementation details needs to be exposed for an object to function properly. However, by using abstract classes and interfaces, we can achieve a high level of abstraction in our code.
Browse our course links : https://www.justacademy.co/all-courses
To Join our FREE DEMO Session: Click Here
Contact Us for more info:
- Message us on Whatsapp: +91 9987184296
- Email id: info@justacademy.co
Java Problem Solving Interview Questions
Sap Sd Interview Questions Answers
Interview Questions On Concurrency In Java
