What is the primary purpose of an interface in OOP?

In Object-Oriented Programming (OOP), an interface is used to define a contract that implementing classes must follow.

An interface contains method declarations without complete implementation. Any class that implements the interface must provide definitions for those methods.

Interfaces help achieve:

• Abstraction

• Multiple inheritance support

• Standardization of behavior

Example:

interface Animal
{
    void sound();
}

class Dog implements Animal
{
    public void sound()
    {
        System.out.println("Bark");
    }
}

Here, the Dog class must implement the sound() method defined in the interface.

Therefore, the main purpose of an interface is to define methods that implementing classes must implement.