javaCopy code
public interface QuackObservable {
    void registerObserver(Observer observer);
    void notifyObservers();
}

• Explanation:

1. public interface QuackObservable {
   • This declares a public interface named QuackObservable.
   • It is intended to be implemented by classes that need to be observed for quacking events.
2. void registerObserver(Observer observer);
   • This declares an abstract method registerObserver, taking an Observer parameter.
   • Classes implementing QuackObservable will provide concrete implementations for registering observers.
3. void notifyObservers();
   • This declares an abstract method notifyObservers.
   • Classes implementing QuackObservable will provide concrete implementations for notifying registered observers.
4. }
   • Closes the QuackObservable interface.

• Overall Explanation:
  • The QuackObservable interface provides a contract for objects that can be observed for quacking events.
  • Classes implementing this interface must provide methods to register and notify observers.
  • This interface is part of the Observer Pattern, allowing objects (ducks) to notify and interact with a set of observers (objects interested in duck quacking events).