What time do you use the Callable object to call call () in Java Executor?

Here are some sample code for example What I need to know is when calling call () on calllable? What triggered it?

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); //**DOES THIS CALL call()?**
      set.add(future);
    }
    int sum = 0;
    for (Future<Integer> future : set) {
      sum += future.get();//**OR DOES THIS CALL call()?**
    }
    System.out.printf("The sum of lengths is %s%n",sum);
    System.exit(sum);
  }
}

Solution

Once the callable is submitted, the executor schedules the callable for execution Depending on the executing program, this may happen directly or after the thread is available

On the other hand, the call to get only waits to retrieve the calculation result

Therefore, to be precise: between the intermediate submission being called and the call return, the call can be called