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POAkka actor tutorial in Scala to multithreading in Java
 

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    <p>I tried to convert the Getting-started Akka tutorial from Scala to Java and replace actors with threads.</p> <p>The tutorial can be found here <a href="http://typesafe.com/resources/tutorials/getting-started-with-akka-scala.html" rel="nofollow">http://typesafe.com/resources/tutorials/getting-started-with-akka-scala.html</a></p> <p>The original Pi.scala file can be checked out from Typesafe giter8 template repository </p> <p><code>g8 typesafehub/akka-first-tutorial-scala</code></p> <p>I would like to know if what I did is correct.</p> <p>And this is my Pi.java</p> <pre><code>import java.util.ArrayList; import java.util.List; import java.util.concurrent.*; public class Pi { /** * @param args */ public static void main(String[] args) { // TODO Auto-generated method stub Listener listener = new Listener(); //calculate(nrOfWorkers = 10, nrOfElements = 10000, nrOfMessages = 10000) Master master = new Master(4, 1000, 1000, listener); master.calculate(); } } class Worker implements Callable&lt;Double&gt; { private int start; private int nrOfElements; public Worker(int start, int nrOfElements) { this.start = start; this.nrOfElements = nrOfElements; } @Override public Double call() throws Exception { double acc = 0.0; for(int i = start; i &lt; start + nrOfElements; i++) { acc += 4.0 * (1 - (i % 2) * 2) / (2 * i + 1); } return acc; } } class Listener { public void PiApproximation(double pi, long duration) { System.out.println(String.format("\n\tPi approximation: \t\t%s\n\tCalculation time: \t%s", pi, duration)); } } class Master { private double pi = 0.0; private int nrOfResults = 0; private final long start = java.lang.System.currentTimeMillis(); private int nrOfWorkers; private int nrOfMessages; private int nrOfElements; private Listener listener; private ExecutorService executor; public Master(int nrOfWorkers, int nrOfMessages, int nrOfElements, Listener listener) { this.nrOfWorkers = nrOfWorkers; this.nrOfMessages = nrOfMessages; this.nrOfElements = nrOfElements; this.listener = listener; //Round robin scheduling is not enforced here as in akka. executor = Executors.newFixedThreadPool(nrOfWorkers); } public void calculate() { List&lt;Future&lt;Double&gt;&gt; list = new ArrayList&lt;Future&lt;Double&gt;&gt;(); for (int i = 0; i &lt; nrOfMessages; i++) { Callable&lt;Double&gt; worker = new Worker(i * nrOfElements, nrOfElements); Future&lt;Double&gt; submit = executor.submit(worker); list.add(submit); } for (Future&lt;Double&gt; future : list) { try { pi += future.get(); } catch (InterruptedException e) { e.printStackTrace(); } catch (ExecutionException e) { e.printStackTrace(); } } //send results to listener listener.PiApproximation(pi, java.lang.System.currentTimeMillis() - start); executor.shutdown(); } } </code></pre>
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