您可以使用ExecutorCompletionService。文档甚至为您的确切用例提供了一个示例:

相反，假设你想使用任务集的第一个非空结果，忽略任何遇到异常的任务，并在第一个任务准备就绪时取消所有其他任务:

void solve(Executor e, Collection<Callable<Result>> solvers) throws InterruptedException {
    CompletionService<Result> ecs = new ExecutorCompletionService<Result>(e);
    int n = solvers.size();
    List<Future<Result>> futures = new ArrayList<Future<Result>>(n);
    Result result = null;
    try {
        for (Callable<Result> s : solvers)
            futures.add(ecs.submit(s));
        for (int i = 0; i < n; ++i) {
            try {
                Result r = ecs.take().get();
                if (r != null) {
                    result = r;
                    break;
                }
            } catch (ExecutionException ignore) {
            }
        }
    } finally {
        for (Future<Result> f : futures)
            f.cancel(true);
    }

    if (result != null)
        use(result);
}

这里需要注意的重要一点是，ec .take()将获得第一个完成的任务，而不仅仅是第一个提交的任务。因此，您应该按照完成执行(或抛出异常)的顺序获取它们。

如果你正在使用Java 8并且不想操纵CompletableFutures，我已经编写了一个工具来检索List<Future<T>>使用流的结果。关键是禁止在它抛出时映射(Future::get)。

public final class Futures
{

    private Futures()
    {}

    public static <E> Collector<Future<E>, Collection<E>, List<E>> present()
    {
        return new FutureCollector<>();
    }

    private static class FutureCollector<T> implements Collector<Future<T>, Collection<T>, List<T>>
    {
        private final List<Throwable> exceptions = new LinkedList<>();

        @Override
        public Supplier<Collection<T>> supplier()
        {
            return LinkedList::new;
        }

        @Override
        public BiConsumer<Collection<T>, Future<T>> accumulator()
        {
            return (r, f) -> {
                try
                {
                    r.add(f.get());
                }
                catch (InterruptedException e)
                {}
                catch (ExecutionException e)
                {
                    exceptions.add(e.getCause());
                }
            };
        }

        @Override
        public BinaryOperator<Collection<T>> combiner()
        {
            return (l1, l2) -> {
                l1.addAll(l2);
                return l1;
            };
        }

        @Override
        public Function<Collection<T>, List<T>> finisher()
        {
            return l -> {

                List<T> ret = new ArrayList<>(l);
                if (!exceptions.isEmpty())
                    throw new AggregateException(exceptions, ret);

                return ret;
            };

        }

        @Override
        public Set<java.util.stream.Collector.Characteristics> characteristics()
        {
            return java.util.Collections.emptySet();
        }
    }

这需要一个像c#一样工作的AggregateException

public class AggregateException extends RuntimeException
{
    /**
     *
     */
    private static final long serialVersionUID = -4477649337710077094L;

    private final List<Throwable> causes;
    private List<?> successfulElements;

    public AggregateException(List<Throwable> causes, List<?> l)
    {
        this.causes = causes;
        successfulElements = l;
    }

    public AggregateException(List<Throwable> causes)
    {
        this.causes = causes;
    }

    @Override
    public synchronized Throwable getCause()
    {
        return this;
    }

    public List<Throwable> getCauses()
    {
        return causes;
    }

    public List<?> getSuccessfulElements()
    {
        return successfulElements;
    }

    public void setSuccessfulElements(List<?> successfulElements)
    {
        this.successfulElements = successfulElements;
    }

}

该组件的作用与c#的Task.WaitAll完全相同。我正在开发一个与CompletableFuture相同的变体。allOf(相当于Task.WhenAll)

我这样做的原因是我正在使用Spring的ListenableFuture，并不想移植到CompletableFuture，尽管这是一种更标准的方式

CompletionService将使用.submit()方法获取你的Callables，你可以使用.take()方法检索计算出的期货。

您一定不能忘记的一件事是通过调用.shutdown()方法来终止ExecutorService。此外，只有在保存了对执行器服务的引用时才能调用此方法，因此请确保保留一个引用。

示例代码-对于要并行处理的固定数量的工作项:

ExecutorService service = Executors.newFixedThreadPool(Runtime.getRuntime().availableProcessors());

CompletionService<YourCallableImplementor> completionService = 
new ExecutorCompletionService<YourCallableImplementor>(service);

ArrayList<Future<YourCallableImplementor>> futures = new ArrayList<Future<YourCallableImplementor>>();

for (String computeMe : elementsToCompute) {
    futures.add(completionService.submit(new YourCallableImplementor(computeMe)));
}
//now retrieve the futures after computation (auto wait for it)
int received = 0;

while(received < elementsToCompute.size()) {
 Future<YourCallableImplementor> resultFuture = completionService.take(); 
 YourCallableImplementor result = resultFuture.get();
 received ++;
}
//important: shutdown your ExecutorService
service.shutdown();

示例代码-对于要并行处理的动态数量的工作项:

public void runIt(){
    ExecutorService service = Executors.newFixedThreadPool(Runtime.getRuntime().availableProcessors());
    CompletionService<CallableImplementor> completionService = new ExecutorCompletionService<CallableImplementor>(service);
    ArrayList<Future<CallableImplementor>> futures = new ArrayList<Future<CallableImplementor>>();

    //Initial workload is 8 threads
    for (int i = 0; i < 9; i++) {
        futures.add(completionService.submit(write.new CallableImplementor()));             
    }
    boolean finished = false;
    while (!finished) {
        try {
            Future<CallableImplementor> resultFuture;
            resultFuture = completionService.take();
            CallableImplementor result = resultFuture.get();
            finished = doSomethingWith(result.getResult());
            result.setResult(null);
            result = null;
            resultFuture = null;
            //After work package has been finished create new work package and add it to futures
            futures.add(completionService.submit(write.new CallableImplementor()));
        } catch (InterruptedException | ExecutionException e) {
            //handle interrupted and assert correct thread / work packet count              
        } 
    }

    //important: shutdown your ExecutorService
    service.shutdown();
}

public class CallableImplementor implements Callable{
    boolean result;

    @Override
    public CallableImplementor call() throws Exception {
        //business logic goes here
        return this;
    }

    public boolean getResult() {
        return result;
    }

    public void setResult(boolean result) {
        this.result = result;
    }
}

如果你想合并一个列表的CompletableFutures，你可以这样做:

List<CompletableFuture<Void>> futures = new ArrayList<>();
// ... Add futures to this ArrayList of CompletableFutures

// CompletableFuture.allOf() method demand a variadic arguments
// You can use this syntax to pass a List instead
CompletableFuture<Void> allFutures = CompletableFuture.allOf(
            futures.toArray(new CompletableFuture[futures.size()]));

// Wait for all individual CompletableFuture to complete
// All individual CompletableFutures are executed in parallel
allFutures.get();

有关Future和CompletableFuture的更多详细信息，有用的链接: 1. 未来:https://www.baeldung.com/java-future 2. CompletableFuture: https://www.baeldung.com/java-completablefuture 3.CompletableFuture: https://www.callicoder.com/java-8-completablefuture-tutorial/

也许这会有帮助(没有什么会被原始的线取代，耶!) 我建议用一个分开的线程运行每个Future家伙(它们并行)，然后当其中一个得到错误时，它只是信号管理器(Handler类)。

class Handler{
//...
private Thread thisThread;
private boolean failed=false;
private Thread[] trds;
public void waitFor(){
  thisThread=Thread.currentThread();
  List<Future<Object>> futures = getFutures();
  trds=new Thread[futures.size()];
  for (int i = 0; i < trds.length; i++) {
    RunTask rt=new RunTask(futures.get(i), this);
    trds[i]=new Thread(rt);
  }
  synchronized (this) {
    for(Thread tx:trds){
      tx.start();
    }  
  }
  for(Thread tx:trds){
    try {tx.join();
    } catch (InterruptedException e) {
      System.out.println("Job failed!");break;
    }
  }if(!failed){System.out.println("Job Done");}
}

private List<Future<Object>> getFutures() {
  return null;
}

public synchronized void cancelOther(){if(failed){return;}
  failed=true;
  for(Thread tx:trds){
    tx.stop();//Deprecated but works here like a boss
  }thisThread.interrupt();
}
//...
}
class RunTask implements Runnable{
private Future f;private Handler h;
public RunTask(Future f,Handler h){this.f=f;this.h=h;}
public void run(){
try{
f.get();//beware about state of working, the stop() method throws ThreadDeath Error at any thread state (unless it blocked by some operation)
}catch(Exception e){System.out.println("Error, stopping other guys...");h.cancelOther();}
catch(Throwable t){System.out.println("Oops, some other guy has stopped working...");}
}
}

我不得不说上面的代码会出错(没有检查)，但我希望我可以解释解决方案。请试一试。

我有一个实用工具类，它包含这些:

@FunctionalInterface
public interface CheckedSupplier<X> {
  X get() throws Throwable;
}

public static <X> Supplier<X> uncheckedSupplier(final CheckedSupplier<X> supplier) {
    return () -> {
        try {
            return supplier.get();
        } catch (final Throwable checkedException) {
            throw new IllegalStateException(checkedException);
        }
    };
}

一旦你有了这些，使用静态导入，你可以像这样简单地等待所有的期货:

futures.stream().forEach(future -> uncheckedSupplier(future::get).get());

你也可以像这样收集他们的所有结果:

List<MyResultType> results = futures.stream()
    .map(future -> uncheckedSupplier(future::get).get())
    .collect(Collectors.toList());

只是重温我的旧帖子，注意到你有另一个悲伤:

但这里的问题是，例如，如果第4个future抛出异常，那么我将不必要地等待前3个future可用。

在这种情况下，简单的解决方案是并行执行:

futures.stream().parallel()
 .forEach(future -> uncheckedSupplier(future::get).get());

这样，第一个异常虽然不会停止future，但会中断foreach语句，就像在串行示例中一样，但由于所有异常都是并行等待的，因此您不必等待前3个异常完成。