Java：ExecutorService和Callables，无法捕获异常

Question

I'm trying to figure out why the below code doesn't print out the stack trace of a NumberFormatException when I run it?

I'm not sure if it is common to use callables and ExecutorService in this way, I googled and couldn't find a solution to my problem... there may be something really obvious that I'm not seeing.

import java.util.ArrayList;
import java.util.concurrent.Callable;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;

public class CallablesTest {

    private final static ArrayList<Callable<Void>> mCallables = new ArrayList<>();
    private final static ExecutorService mExecutor = Executors.newFixedThreadPool(4);

    public static void main(String[] args) throws Exception{
        testMethod();
    }

    static void testMethod() throws Exception {

        mCallables.clear();

        for(int i=0; i<4; i++){
            mCallables.add(new Callable<Void>() {

                @Override
                public Void call() throws Exception {
                    //if (Thread.currentThread().isInterrupted()) {
                    //    throw new InterruptedException("Interruption");
                    //}
                    System.out.println("New call");
                    Double.parseDouble("a");

                    return null;
                } //end call method

            }); //end callable anonymous class
        }
        try {
            mExecutor.invokeAll(mCallables);
            mExecutor.shutdown();
        } catch (Exception e) {
          e.printStackTrace();
        }
    }
}

Answer 1

I think I may have found the answer to my own question... if you get the future objects returned from ExecutorService.invokeAll... and then surround the Future "get" calls with a try/catch block, you can catch the exception

import java.util.ArrayList;
import java.util.List;
import java.util.concurrent.Callable;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.Future;

public class ThreadTest {

    private final static ArrayList<Callable<Boolean>> mCallables = new ArrayList<>();
    private final static ExecutorService mExecutor = Executors.newFixedThreadPool(4);

    public static void main(String[] args) throws Exception{
        testMethod();
    }

    static void testMethod() throws Exception {

        mCallables.clear();

        for(int i=0; i<4; i++){
            mCallables.add(new Callable<Boolean>() {

                @Override
                public Boolean call() throws Exception {
                    //if (Thread.currentThread().isInterrupted()) {
                    //    throw new InterruptedException("Interruption");
                    //}
                    System.out.println("New call");

                    double d = Double.parseDouble("a");

                    return true;
                } //end call method

            }); //end callable anonymous class
        }
        try {
            List<Future<Boolean>> f= mExecutor.invokeAll(mCallables);
            f.get(1).get();
            f.get(2).get();
            f.get(3).get();
            f.get(0).get();

        } catch (Exception e) {
            String s = e.toString();
            System.out.println(s);
        }

        mExecutor.shutdown();
    }
}