Functional Interfaces

Functional interfaces are a key concept in Java, particularly introduced in Java 8, that facilitate functional programming within an object-oriented framework. A functional interface is defined as an interface that contains exactly one abstract method, allowing it to be used as the target for lambda expressions and method references. This design promotes cleaner and more concise code by enabling developers to pass behavior as parameters. The @FunctionalInterface annotation can be used to indicate that an interface is intended for functional use, ensuring that it adheres to the single abstract method requirement. This approach enhances code reusability and flexibility in Java applications.