Can you explain what is meant by 'method reference' in programming?

In Java, a method reference is a way to pass a method as an object that can be invoked later. It is a shortened form of lambda expression, allowing you to refer to an existing method by its name.

Method references come in several types:

• Reference to a static method: ClassName::staticMethod
• Reference to an instance method of a particular object: instance::instanceMethod
• Reference to an instance method of an arbitrary object of a particular type: ClassName::instanceMethod
• Reference to a constructor: ClassName::new

Example:

import java.util.Arrays;
import java.util.List;

public class MethodReferenceExample {
    public static void main(String[] args) {
        List<String> names = Arrays.asList("Anna", "Bob", "Charlie");

        // Using a method reference to print each element
        names.forEach(System.out::println);
    }
}

Here, System.out::println is a reference to the println method of the System.out object. It is a convenient and readable way to pass behavior to functional interfaces.