How to rewrite a class definition with an interface to enable polymorphic behavior?

To ensure polymorphic behavior when implementing a class with an interface in Java, you need to:

1. Define an interface with the necessary methods.
2. Create a class that implements this interface and implement all its methods.
3. Use variables of the interface type to store objects of classes that implement this interface.

Example:

// Interface
public interface Animal {
    void makeSound();
}

// Class implementing the interface
public class Dog implements Animal {
    @Override
    public void makeSound() {
        System.out.println("Woof!");
    }
}

public class Cat implements Animal {
    @Override
    public void makeSound() {
        System.out.println("Meow!");
    }
}

// Using polymorphism
public class Main {
    public static void main(String[] args) {
        Animal myDog = new Dog();
        Animal myCat = new Cat();
        
        myDog.makeSound(); // Outputs: Woof!
        myCat.makeSound(); // Outputs: Meow!
    }
}

Thus, objects of different classes can be handled through a common interface, which provides polymorphism.