The java.util.function package contains functional interfaces that are essential for functional programming in Java, such as Function, Consumer, Supplier, and Predicate, which can be used extensively with streams and lambda expressions.
Source Code
import java.util.function.Function;
public class FunctionInterfaceExample {
public static void main(String[] args) {
Function func = x -> x.length();
Integer apply = func.apply("This is Java 8");
System.out.println(apply); // Outputs: 13
}
}