Functional Interfaces

Functional-Interfaces

Functional interfaces are a key concept introduced in Java 8, representing interfaces that contain exactly one abstract method, also known as Single Abstract Method (SAM) interfaces. This characteristic allows them to be used as the basis for lambda expressions, which provide a concise way to express instances of functional interfaces. While the use of the @FunctionalInterface annotation is not mandatory, it helps enforce the rule of having a single abstract method, ensuring that the interface remains suitable for lambda expressions. Java’s standard library includes numerous built-in functional interfaces, facilitating functional programming practices within the object-oriented paradigm.

Essential Java

Introduction In Java 8+, a functional interface is an interface that has just one abstract method (aside from the methods of Object). See JLS §9.8. Functional Interfaces .

Functional Interfaces: The Hidden Bridge Between OOP and FP in Java..

Javarevisited

🌱 What is a Functional Interface? A functional interface is an interface that has exactly one abstract method (a.k.a. SAM — Single Abstract Method). Examples you already know: Runnable (run)

Functional Interface vs @FunctionalInterface

Javarevisited

Introduction The functional interface is an interface that contains only one abstract method . You can use lambda expressions to create instances of this interface.

Understand functional interfaces

Java Best Practices

In Java 8 the @FunctionalInterface annotation was introduced, allowing API developers to designate that a particular class is intended for use in lambda expressions. It is not necessary that a class ...

Understand functional interfaces

Java Best Practices

Java Functional Interface and Lamda Implementation

Level Up Coding

A functional interface in Java is an interface that contains only a single abstract (unimplemented) method. A functional interface may have defaulted, and static methods may have an implementation…

Functional Java 1 — Functional Interfaces

Level Up Coding

Java 8 is undoubtedly one of the most significant releases in Java history. While Java remains an inherently object-oriented language, the introduction of core functional features has brought a breath...

Interfaces

Introduction to Programming Using Java

Section 5.7 Interfaces Some object-oriented programming languages, such as C++, allow a class to extend two or more superclasses. This is called multiple inheritance . In the illustration below, for e...

Java Functional Interfaces For the Impatient: Part 1

Level Up Coding

In this article, we will learn about Java Functional Interfaces with coding examples. This is just part one of the series as I will try to cover the main functional interfaces which come under Packag...

Interfaces

Essential Java

Introduction An interface is a reference type, similar to a class, which can be declared by using interface keyword. Interfaces can contain only constants, method signatures, default methods, static m...

Interfaces

Codecademy

An interface is composed of set of method signatures. These method signatures define the input and return values of which a data type or struct can conform to. In order to implement an interface, the ...

Interfaces

Codecademy

Interfaces are used to “shape” an object by describing a certain set of members and/or type annotations. Syntax Interfaces may be declared by: Starting with the interface keyword. Giving the interface...