[学习交流] Callable、Future的理解

* 目的：了解callable、future
*
*/
public class CallableAndFutureTest {
public static void main(String[] args) {
//ExecutorService singlePool = Executors.newSingleThreadExecutor();
/**
* Callable有返回值，而且会抛异常
* 在线程池中用submit调用，返回一个Future
*/
/*Future<String> future =
singlePool.submit(new Callable<String>(){
public String call() throws Exception {
Thread.sleep(2000);
return "hello";
}
});
try {
System.out.println(future.get()); //通过get（）方法得到结果
System.out.println(future.get(1, TimeUnit.SECONDS)); //如果多少秒还没得到结果就抛异常
} catch (InterruptedException e) {
e.printStackTrace();
} catch (ExecutionException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (TimeoutException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}*/
ExecutorService pool = Executors.newFixedThreadPool(3);
/**
* 等到一组Future，谁先返回，谁先加入到CompletionService的队列中
*/
CompletionService<Integer> completionService = new ExecutorCompletionService<Integer>(pool);
for(int i=0;i<10;i++){
final int num = i;
completionService.submit(new Callable<Integer>() {
public Integer call() throws Exception {
System.out.println("callable now is"+num);
return num;
}
});
}
for(int i=0;i<10;i++){
try {
System.out.println(completionService.take().get());
} catch (InterruptedException e) {
e.printStackTrace();
} catch (ExecutionException e) {
e.printStackTrace();
}
}
}
}

复制代码

帐号		自动登录	找回密码
密码			加入黑马

0 个回复