What are method references?

Method references are a feature of Java 8 . The biggest addition in Java8 has been lambda expressions . Method Reference is the shorthand syntax for a lambda expression that executes just ONE method. It allows us to reference constructors or methods without executing them. Method references and Lambda are similar in that they both require a target type that consist of a compatible functional interface. An interface with only one method is called a functional interface. For example, Comparable, Runnable, AutoCloseable are some functional interfaces in Java. The double colon (::) operator is used for method reference. You can access a method (lambda expression) using the :: notation.

 
Integer::compare

A method reference can be used to point the following types of methods:

Static methods
Instance methods
Constructors using new operator (TreeSet::new)

Example

 
      import java.util.*;
      public class TestClass {
        public static void main(String[] args) {
            List weekDays = new ArrayList();
            weekDays.add("Monday");
            weekDays.add("Tuesday");
            weekDays.add("Wednesday");
            weekDays.add("Thursday");
            weekDays.add("Friday");
            weekDays.forEach(System.out::println);
        }
      }

Output

Monday

Tuesday

Wednesday

Thursday

Friday

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