Functional Interfaces in Java

Functional Interfaces in Java — a practical guide to Java functional interface with clear examples you can reuse in real projects.

Java Tutorial Series (62/90). Prefer one article? Read the complete Java tutorial.

Short description

Common ones: `Predicate`, `Function`, `Consumer`, `Supplier`, and custom `@FunctionalInterface` types.

Predicate example

import java.util.function.Predicate;

Predicate<Integer> even = n -> n % 2 == 0;
System.out.println(even.test(4));