:: (double colon) operator in Java 8

Question

I was exploring the Java 8 source and found this particular part of code very surprising:

//defined in IntPipeline.java
@Override
public fin         


        

Answer 1

:: Operator was introduced in java 8 for method references. A method reference is the shorthand syntax for a lambda expression that executes just ONE method. Here's the general syntax of a method reference:

Object :: methodName

We know that we can use lambda expressions instead of using an anonymous class. But sometimes, the lambda expression is really just a call to some method, for example:

Consumer c = s -> System.out.println(s);

To make the code clearer, you can turn that lambda expression into a method reference:

Consumer c = System.out::println;