Lambdas

From APIDesign

Revision as of 17:31, 24 September 2013

Lambdas are Java implementation of Closures and are coming in JDK8.

Don't Know the Syntax?

Yesterday I had a duty at NetBeans JavaOne2013 booth. Somebody asked whether NetBeans support lambda. Sure, NetBeans 7.4 do! was my answer. But how to demonstrate that? I tried:

class LamdaTest {
  static void doRun(Runnable r) {
    r.run();
  }
 
  public static void main(String... args) {
    doRun({ System.out.println("Hello World!"); });
  }
}

it did not compile. Then I tried to change the lambda line to:

doRun( => { System.out.println("Hello World!"); });

No luck either. I gave up and rewrote the code to old good verbose but familiar inner class syntax:

public static void main(String... args) {
    doRun(new Runnable() {
        @Override
        public void run() {
            System.out.println("Hello World!");
        }
    });
  }

and suddenly a hint appeared:

after applying the hint I finally got lambda syntax right:

public class LambdaTest {
 static void doRun(Runnable r) {
    r.run();
  }
 
  public static void main(String... args) {
    doRun(() -> System.out.println("Hello World!"));
  }    
}

NetBeans own source code sticks (and will stick) with JDK7 for a while. As such I don't have much chances to use lambdas, but I can say I can write lambdas, now!

Just one thing I don't understand? Why people claim NetBeans IDE does not understand lambdas?