Can you explain interfaces
What is an Interface?
- Definition: An interface is a contract or a blueprint in programming that defines a set of methods (functions) that a class must implement. However, an interface does not provide the actual implementation of these methods.
- Purpose: Interfaces are used to achieve abstraction and polymorphism in object-oriented programming. They allow different classes to implement the same set of methods in their own way.
Key Characteristics of Interfaces
- Method Signatures Only: Interfaces can contain:
- Method signatures (the method name, return type, and parameters).
- No method bodies (implementation), only declarations.
interface Animal {
void sound(); // Method signature with no implementation
}
Multiple Inheritance: A class can implement multiple interfaces, allowing for a form of multiple inheritance.
interface Swimmer {
void swim();
}
interface Flyer {
void fly();
}
class Duck implements Animal, Swimmer, Flyer {
@Override
public void sound() {
System.out.println("Quack");
}
@Override
public void swim() {
System.out.println("Duck swims");
}
@Override
public void fly() {
System.out.println("Duck flies");
}
}
Public by Default: All methods in an interface are implicitly public and abstract, meaning they can be accessed from outside the implementing class and must be overridden.
Why Use Interfaces?
Flexibility and Reusability:
Interfaces allow different classes to provide their own implementations of the same method. This makes your code flexible and reusable.
Decoupling Code:
Using interfaces helps to decouple the code. You can write code that works with interfaces rather than concrete implementations, making it easier to change or extend your code later.
Defining Common Behavior:
Interfaces define a common behavior for different classes. For example, any class that implements the Animal interface must have a sound() method, ensuring that all animals can “speak” in some way.
Simple Analogy
Think of an interface as a contract:
Imagine you have a contract for a service provider that states, “You must provide a method to clean.” The service provider (class) can decide how to clean (implementation), but they must follow the contract (interface) by implementing the required method.
Interface: A blueprint for classes that defines methods without implementation.
Key Features: Method signatures only, multiple inheritance, and public by default.
Uses: Provides flexibility, promotes code reuse, and defines common behavior.