如何从线程提交Callable到ExecutorService

Question

I have an application which creates a new thread on a socket connection. I would like to submit a Callable from this thread to an ExecutorService. The Callable needs to execute a program via a command line argument, so I don't want to do this via the connection thread.

The problem is, I don't know how to submit the Callable to an ExecutorService which has a set thread count.

I had considered doing this with a singleton and writing a submit method to submit my Callable to the ExecutorService instance but being unfamiliar with the api, I wasn't sure if this was sensible.

Any help is greatly appreciated, Thanks.

Answer 1

I would try

 static final ExecutorService service = Executors.newFixedThreadPool(4);

 Callable call = 
 service.submit(call);

Answer 2

Here is some code I find online about your problem :

public class CallableExample {

  public static class WordLengthCallable
        implements Callable {
    private String word;
    public WordLengthCallable(String word) {
      this.word = word;
    }
    public Integer call() {
      return Integer.valueOf(word.length());
    }
  }

  public static void main(String args[]) throws Exception {
    ExecutorService pool = Executors.newFixedThreadPool(3);
    Set<Future<Integer>> set = new HashSet<Future≶Integer>>();
    for (String word: args) {
      Callable<Integer> callable = new WordLengthCallable(word);
      Future<Integer> future = pool.submit(callable);
      set.add(future);
    }
    int sum = 0;
    for (Future<Integer> future : set) {
      sum += future.get();
    }
    System.out.printf("The sum of lengths is %s%n", sum);
    System.exit(sum);
  }
}

Answer 3

There is method submit():

ExecutorService service = Executors.(get the one here you like most)();
Callable<Something> callable = (your Callable here);
Future<AnotherSomething> result = service.submit(callable);

Please note than when using executor service, you have no control over when the task actually starts.