The Difference Between Interface and Abstract Classes in Object-Oriented Programming
Object-Oriented Programming (OOP) is a popular programming paradigm that uses classes to organize and structure code. Two types of classes used in OOP are interface and abstract classes. While they share some similarities, there are distinct differences between the two.
What is an Interface?
An interface is a type of class that only defines method signatures with empty bodies. It serves as a contract that specifies what methods a class must implement. Interfaces are used to define the behavior of a class without actually implementing it.
In other words, an interface is a list of methods that a class must implement. It defines the capabilities of a class without specifying how those capabilities are implemented. This allows for greater flexibility and modularity in code design.
What is an Abstract Class?
An abstract class is a class that cannot be instantiated. It serves as a blueprint for creating subclasses that inherit the characteristics of the abstract class. Abstract classes contain both abstract and concrete methods.
Abstract methods are method signatures without bodies, similar to interfaces. They define the behavior of the method without actually implementing it. Concrete methods, on the other hand, have bodies and provide default behavior for subclasses to use.
In other words, an abstract class is a template for creating subclasses that share common characteristics. It provides a foundation for building more specific classes from a general class.
The Key Differences
One of the key differences between interface and abstract classes is that interfaces cannot have concrete methods, while abstract classes can. Another difference is that a class can implement multiple interfaces, but can only inherit from one abstract class.
A class that implements an interface must implement all of its methods, whereas a class that inherits from an abstract class can either implement or override its methods. Additionally, abstract classes can have non-abstract methods, while interfaces cannot.
When to Use Each
Interfaces are typically used when you want to define the behavior of a class, but not its implementation. They allow for greater flexibility and modularity in code design. Use interfaces when you need a contract between classes that specifies the methods they must implement.
Abstract classes, on the other hand, are used when you want to provide a base implementation for a family of classes that share common characteristics. They allow for easier code reuse and a more streamlined design. Use abstract classes when you need to provide a template for creating related classes.
Conclusion
In summary, interface and abstract classes are two types of classes used in object-oriented programming. While they share some similarities, they have distinct differences in their implementation and purpose. Use interfaces when you want to define the behavior of a class without implementing it, and use abstract classes when you want to provide a foundation for creating related classes.
Table difference between interface and abstract
| Attribute | Interface | Abstract |
|---|---|---|
| Keyword | interface | abstract |
| Usage | Defines a contract for classes to implement. | Defines a base class that cannot be instantiated directly. |
| Method Implementation | None | Can have implemented and abstract methods. |
| Inheritance | Can extend multiple interfaces. | Can only extend one class (abstract or concrete). |
| Constructor | No constructors. | Can have constructors. |