Groovy power

The concurrent API that was added to Java 5 is very powerful for sumbitting tasks to a worker thread pool, but when you combine it with the Groovy ability to implement single-method interfaces with closures you have a real winner.

import java.util.concurrent.Callable
import java.util.concurrent.Executors

def executorService = Executors.newFixedThreadPool(4)

def x = {
   20.times {
       println "X"
   }
} as Callable

def y = {
   20.times {
       println " Y"
   }
} as Callable

executorService.invokeAll([x, y])

executorService.shutdown()

which of course has an output similar to this:

X
 Y
 Y
 Y
X
 Y
X
 Y
X
 Y
 Y
X
X
 Y
X
 Y
 Y
X
X
X

Pretty neat, huh?