What are functional interfaces used for in Java 8?

Question

I came across a new term in Java 8: "functional interface". I could only find one use of it while working with lambda expressions.

Java 8 provides

Answer 1

You can use lambda in Java 8

public static void main(String[] args) {
    tentimes(inputPrm - > System.out.println(inputPrm));
    //tentimes(System.out::println);  // You can also replace lambda with static method reference
}

public static void tentimes(Consumer myFunction) {
    for (int i = 0; i < 10; i++)
        myFunction.accept("hello");
}

For further info about Java Lambdas and FunctionalInterfaces