Abstract Class

Definition of Abstract Class

An abstract class is a high-level (or base) class in object-oriented programming that cannot be directly instantiated, but instead serves as a blueprint for designing concrete, derived classes. Abstract classes contain at least one abstract method, which has no implementation within the abstract class itself, leaving the specifics to be defined through subclassing. These classes provide a structure and common behavior for their subclasses, promoting reusability, and code organization.


The phonetics of the keyword “Abstract Class” would be:Abstract: /ˈæb.strækt/Class: /klæs/

Key Takeaways

  1. An abstract class is a class that cannot be instantiated itself, and is designed to be subclassed by other classes.
  2. Abstract classes can contain abstract methods, which are methods with no implementation, and should be overridden by the subclasses.
  3. Using abstract classes promotes code reusability and better organization, by providing a common base for related classes.

Importance of Abstract Class

The technology term “Abstract Class” is important because it serves as a foundation for designing modular, reusable, and extensible software in object-oriented programming languages, like Java or C#. Abstract classes provide a blueprint to define common characteristics, methods, and behaviors that can be inherited by derived classes, streamlining the development process and promoting code reusability.

They enforce a consistent structure across related classes and can be used as a common interface for polymorphic operations, which boosts flexibility and adaptability in software systems.

By utilizing abstract classes, developers can create a well-organized, maintainable, and scalable codebase, ultimately improving efficiency and software quality.


Abstract classes serve a vital purpose in object-oriented programming, particularly when it comes to designing software systems. They provide a high-level blueprint for the functionalities and behaviors that similar, related classes should possess, without dictating the specifics. An abstract class establishes a common interface for its subclasses that derive from it, allowing them to share common attributes and methods.

This not only encourages the consistent implementation of functionalities across related classes but also promotes code reusability and modularity. By following the principles of abstraction and inheritance, abstract classes facilitate better organization of code, enable simpler maintenance, and reduce the risk of errors. In practice, abstract classes act as templates for concrete classes, where concrete classes are those that can be directly instantiated.

The methods defined in an abstract class are declared as abstract methods, which intentionally lack implementation details. Subclasses of an abstract class are required to provide implementations for these abstract methods, which often account for the variations that may exist among related classes. Furthermore, abstract classes can also contain fully implemented methods and attributes which are common to all subclasses.

Thus, abstract classes fulfill the role of providing a structure for similar classes while allowing the flexibility required to adapt to specific use cases, ultimately emphasizing the versatility and polymorphism supported in object-oriented programming.

Examples of Abstract Class

An abstract class is a concept within object-oriented programming languages, which allows developers to create classes that cannot be instantiated on their own but can be subclassed to create more concrete entities. By having an abstract class, you can define certain functionalities and properties that will be common to all subclasses without the need to rewrite code. Here are three real-world examples involving abstract classes:

Banking System: Suppose you are developing a banking system that has different types of accounts, such as Savings Account, Checking Account, and Business Account. You can create an abstract class called “BankAccount,” which will have common properties like account number, account holder name, and balance, as well as abstract methods for deposit, withdrawal, and calculating interest. Each specific type of account will then inherit from this BankAccount abstract class and implement the abstract methods, providing the specific rules and behavior for each type of account.

Employee Management System: In an employee management system, there can be different types of employees like full-time, part-time or contract-based employees. An abstract class called “Employee” can be created, with common properties like employee ID, name, and address, abstract methods for calculating salary, tax, and benefits. The specific classes for each type of employee, such as “FullTimeEmployee,” “PartTimeEmployee,” and “ContractEmployee,” can then inherit from the base abstract class and provide the implementation for calculating salary, tax, and benefits based on their respective rules.

Graphic Design Software: In a graphic design software, various types of shapes can be drawn, such as circles, rectangles, and triangles. An abstract class called “Shape” can be created, with common properties like x and y coordinates, color, and visibility, as well as abstract methods for calculating the area, perimeter, and drawing the shape on the canvas. Each specific shape class, like “Circle,” “Rectangle,” and “Triangle,” can inherit from this abstract class “Shape” and define their implementations of calculating area, perimeter, and specific drawing routines.

Abstract Class FAQ

1. What is an abstract class?

An abstract class is a class that cannot be instantiated and is meant to be subclassed by other classes. It can have both abstract and non-abstract methods, but at least one abstract method. Abstract classes are declared using the keyword ‘abstract’.

2. Why use an abstract class?

Abstract classes are used when you want to provide a common interface for subclasses or to define a base class with partial implementation, which can then be extended by other classes. Abstract classes promote reusability and consistency in the design of the software.

3. How to create an abstract class?

An abstract class is created using the ‘abstract’ keyword before the class declaration. For example:

abstract class Shape {
  abstract void calculateArea();

4. Can an abstract class have constructors?

Yes, an abstract class can have constructors, but they can only be called during the instantiation of the subclass. Constructors are used to initialize the fields of the abstract class.

5. Can abstract classes have non-abstract methods?

Yes, abstract classes can have both abstract and non-abstract methods. Non-abstract methods in an abstract class provide default or common functionality that can be used by subclasses, while abstract methods must be implemented by the subclasses.

6. Can an abstract class implement interfaces?

Yes, an abstract class can implement one or multiple interfaces. It can provide implementation for some or all methods of the interfaces, and the remaining unimplemented methods must be implemented by the subclasses.

Related Technology Terms

  • Inheritance
  • Polymorphism
  • Encapsulation
  • Interface
  • Method overriding

Sources for More Information

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