Does Java have a `::` operator? [duplicate]

In Java 8 the operator :: has been introduced as a way to refer to a method. Basically, it turns the method into a first-class object, something you can pass to other methods as an argument, store in a variable, and return from a method.

This addition to the syntax is a part of the overall orientation towards the Functional Programming paradigm which is being introduced with Java 8. The elementary feature of FP are higher-order functions—such functions which accept other functions as argument, or return functions. This paradigm allows one to eliminate much boilerplate which now pervades the Java source code.

In Java 8 it allows for referencing of static members of a class, similar to PHP.

public class YourClass {

    public static int comparer(String one, String two){
        return one.length() - two.length();
    }

    public static void main(String[] args) {
        Arrays.sort(args, YourClass::comparer);
        //args are now sorted
    } 

}

As stated in comments, this is Java 8 (and later) only. JDK 7 and below does not have this.

Upto Java 7 there is no double colon operator(::) in java as in C++. But Java 8 introduce double colon operator which is used to refer the methods.

Example(For Static Method)

public class TestClass {

    public void functionTest() {...}

}

We can call function 'functionTest()' by using double colon operator(::).

TestClass t=new TestClass();
t::functionTest

If 'functionTest()' is static then we can refer directly by using class name

TestClass::functionTest

There are four kinds of method references(as written in java doc)

For more information refer java doc