Lambda Expressions: Method References:

Method references are short hand of lambda expression. It is an easy way to delegate a call to an existing method. The method is referenced by using the class name or the object reference with :: separating the method name
e.g. We can call System.out.println with a below statement:

List<Integer> numbers = Arrays.asList(1, 2, 3, 4, 5, 6);
numbers.forEach(System.out::println);

package com.corejava.LambdaExpressions.examples;

//method references are short hand of lambda expressionpublic class MethodReferences {

    interface IMovie {
        Boolean check(Integer id);
    }

    private void testMovieStaticMethodRef() {
        IMovie movie1 = (i) -> i < 100;// movie id less than 100 are     classic movies        IMovie movie2 = MethodReferences::isClassic;
        System.out.println(movie1.check(100));
        System.out.println(movie2.check(99));
    }

    private void testMovieInstanceMethodRef() {
        IMovie movie1 = (id) -> id < 200 && id > 100;
        MethodReferences methodReferences = new MethodReferences();
        IMovie movie2 = methodReferences::isComedy;
        System.out.println(movie1.check(101));
        System.out.println(movie2.check(201));
    }

    public static void main(String[] args) {
        MethodReferences methodReferences = new MethodReferences();
        methodReferences.testMovieStaticMethodRef();
        methodReferences.testMovieInstanceMethodRef();
    }

    private boolean isComedy(Integer id) {
        return id < 200 && id > 100;
    }

    public static Boolean isClassic(Integer id) {
        return id < 100;
    }
}