Re: Parallel processing using Executor?

From:

Daniel Pitts <googlegroupie@coloraura.com>

Newsgroups:

comp.lang.java.programmer

Date:

Tue, 14 Aug 2007 12:29:42 -0700

Message-ID:

<1187119782.780891.295570@m37g2000prh.googlegroups.com>

On Aug 14, 12:15 pm, howa <howac...@gmail.com> wrote:

Hello,

I have a method, e.g. foo(int i), which take an integer i and do some
heavy processing

now, i want to find the summation of foo() of i = 1..10000, I want to
take the advantage of speedup by multithreads, then I use executors to
create the threads...,e.g.

public class Foobar implements Runnable {

        public Foobar() {}

        public void run() {
                System.out.println("thread is running...");
        }

       public int foo(int i) {
              //...
      }

}

Executor tp = Executors.newFixedThreadPool(10);

for (int i =1; i <=10000; i++) {
     tp.execute(new Foobar() );

}

but how can i get back the information return from the execute method,
i.e. from the foo(int i)?

Thanks...

Try this approach:

public class Foobar extends Callable<Integer> {
   final int param;
   public Foobar(int param) {
      this.param = param;
   }

   public Integer call() {
      return foo(param);
   }

    public int foo(int i) {
      return i * 2;
    }
}
public class Main {
  public static void main(String..args) throws Exception {
    Executor tp = Executors.newFixedThreadPool(10);
    List<Future<Integer>> futureObjects = new
ArrayList<Future<Integer>>();
    for (int i =1; i <=10000; i++) {
      futureObjects.add(tp.execute(new Foobar(i)));
    }
    for (Future<Integer> result: futureObjects) {
      System.out.println(result.get());
    }
}