Functional Interfaces

Functional interfaces are a key concept in Java, particularly introduced in Java 8, that facilitate the use of lambda expressions. A functional interface is defined as an interface that contains exactly one abstract method, allowing it to be used as a target for lambda expressions and method references. This design promotes a functional programming style within Java, enabling developers to write more concise and readable code. The @FunctionalInterface annotation can be used to indicate that an interface is intended to be functional, helping to enforce the single abstract method rule and preventing accidental modifications that could disrupt its intended use.