Simplifying OOP in Java: Interfaces

Day 9: Interfaces

After abstraction, the next important step is understanding interfaces.

An interface defines a contract. It tells a class what behavior it must provide, without giving the full implementation itself.

In Java, a class uses the implements keyword to follow that contract.

interface Vehicle {
    void move();
}

class Car implements Vehicle {
    @Override
    public void move() {
        System.out.println("Car is moving");
    }
}

In this example, the interface Vehicle defines the method move().

The Car class then implements that interface and provides the actual behavior.

This is what makes interfaces useful. They create a shared structure while still allowing different classes to behave in their own way.