What are the advantages of Java Functional Interfaces?

Question

(This question already has answers here): question from:https://stackoverflow.com/questions/66064826/what-are-the-advantages-of-java-functional-interfaces

Answer 1

Your questions could be answered if you read manual about functional interfaces and lambdas. Just take a look on difference between lambda expression and usual anonymous class creation. Both variables can be used the same way.

    //using anonymous class 
    Predicate<String> isStringEmptyObj = new Predicate<String>() {
        @Override
        public boolean test(String o) {
            return o.isEmpty();
        }
    };
    System.out.println(isStringEmptyObj.negate().test("asd"));

    //using lambda with reference to existing String object method
    Predicate<String> isStringEmpty = String::isEmpty;
    System.out.println(isStringEmpty.negate().test("asd"));