如何从 thead 返回一个变量(我也有线程句柄)。在这种情况下,静态变量将不起作用。
更新:这是一个转折点,我怎样才能做到这一点而不必阻塞并等待结果?我需要能够轮询创建的线程,如果它挂起的时间太长(例如 > 1 分钟),则将其杀死,然后如果生成的线程花费的时间太长,则继续在主线程中继续。
最佳答案
使用 Callable<V>
而不是 Thread
(或 Runnable
)以便您可以获得 Future<V>
的结果并使用 ExecutorService
调用它。
这是一个 SSCCE ,只需复制'n'粘贴'然后'运行它:
package com.stackoverflow.q2413389;
import java.util.Arrays;
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 Test {
public static void main(String... args) throws Exception {
ExecutorService executor = Executors.newCachedThreadPool();
List<Future<String>> results = executor.invokeAll(Arrays.asList(new Task()));
for (Future<String> result : results) {
System.out.println(result.get()); // Prints "myResult" after 2 seconds.
}
executor.shutdown();
}
}
class Task implements Callable<String> {
public String call() throws Exception {
Thread.sleep(2000); // Do your running task here, this example lasts 2 seconds.
return "myResult";
}
}
更新:根据关于如何在超时后终止它的问题的更新,使用 ScheduledExecutorService
反而。这是稍作更改的代码:
ScheduledExecutorService executor = Executors.newSingleThreadScheduledExecutor();
List<Future<String>> results = executor.invokeAll(Arrays.asList(new Task()), 1, TimeUnit.SECONDS); // Timeout of 1 second.
for (Future<String> result : results) {
if (!result.isCancelled()) {
System.out.println(result.get()); // Won't be printed as the "actual" processing took 2 seconds.
} else {
System.out.println("Task timed out.");
}
}
executor.shutdown();
关于Java:从线程中获取一个值...?,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/2413389/