runnable的线程抛出异常无法捕获

package com.itbuluoge.mythread;import java.util.concurrent.ExecutorService;import java.util.concurrent.Executors;class MyThread implements Runnable{public void run(){throw new RuntimeException();}}public class ExceptionThread{/** * @param args */public static void main(String[] args) {// TODO Auto-generated method stubtry{ExecutorService exec=Executors.newCachedThreadPool();exec.execute(new MyThread());}catch(Exception e){System.out.println("exception");}}}