(1)可以接受的任务类型
submit:
execute:
可以看出:
execute只能接受Runnable类型的任务
submit不管是Runnable还是Callable类型的任务都可以接受,但是Runnable返回值均为void,所以使用Future的get()获得的还是null
(2)返回值
由Callable和Runnable的区别可知:
execute没有返回值
submit有返回值,所以需要返回值的时候必须使用submit
(3)异常
1.execute中抛出异常
execute中的是Runnable接口的实现,所以只能使用try、catch来捕获CheckedException,通过实现UncaughtExceptionHande接口处理UncheckedException
即和普通线程的处理方式完全一致
不管提交的是Runnable还是Callable类型的任务,如果不对返回值Future调用get()方法,都会吃掉异常
先来看下Callable定义
- public interface Callable<V> {
- V call() throws Exception;
- }
- import java.util.concurrent.Callable;
- import java.util.concurrent.ExecutionException;
- import java.util.concurrent.ExecutorService;
- import java.util.concurrent.Executors;
- import java.util.concurrent.Future;
- public class ThreadExceptionTest {
- public static void main(String[] args) {
- ExecutorService executor = Executors.newCachedThreadPool();
- Future<Boolean> future = executor.submit(new CallableTask());
- try {
- future.get();
- } catch (InterruptedException e) {
- e.printStackTrace();
- } catch (ExecutionException e) {
- e.printStackTrace();
- }
- executor.shutdown();//必须不能忘,否则会一致卡在那里
- }
- }
- class CallableTask implements Callable<Boolean>{
- public Boolean call() throws Exception {
- // InputStream in = new FileInputStream(new File("xx.pdf"));
- int num = 3/0;
- return false;
- }
- }
- java.util.concurrent.ExecutionException: java.lang.ArithmeticException: / by zero
- at java.util.concurrent.FutureTask$Sync.innerGet(FutureTask.java:222)
- at java.util.concurrent.FutureTask.get(FutureTask.java:83)
- at my.ThreadExceptionTest.main(ThreadExceptionTest.java:21)
- Caused by: java.lang.ArithmeticException: / by zero
- at my.CallableTask.call(ThreadExceptionTest.java:57)
- at my.CallableTask.call(ThreadExceptionTest.java:1)
- at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:303)
- at java.util.concurrent.FutureTask.run(FutureTask.java:138)
- at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:886)
- at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:908)
- at java.lang.Thread.run(Thread.java:619)