使用FutureTask而不是Callable有什么好处？ [英] what is the advantage of using FutureTask over Callable?

问题描述

提交和轮询任务结果有两种方法

There are two approaches to submitting and polling task for result

FutureTask futureTask = new FutureTask<String>(callable);

1. 使用 Callable <的组合/ code>和 Future 并在 ExecutorService 上提交。使用 future.get（）检索结果。

1. Use combination of Callable and Future and submit on ExecutorService. Retrieve result using future.get().

Future future = service.submit(callable);

使用 FutureTask 。这将包装 Callable ，然后使用 FutureTask 检索结果。

Use FutureTask. This will wrap Callable and then retrieve result using FutureTask.

service.execute(task);

使用<$ c的优点是什么$ c> FutureTask over Callable + Future combination？

What is the advantage of using FutureTask over Callable + Future combination ?

推荐答案

几乎肯定都没有。快速浏览 AbstractExecutorService 的％28java.lang.Runnable％29rel =noreferrer> GrepCode 显示这些方法中的每一个都是最终包装 Callable / Runnable 在 Future 中为您服务。

Almost certainly none at all. A quick browse on GrepCode of the AbstractExecutorService shows each of these methods are simply helper methods that ultimately wrap the Callable/Runnable in a Future for you.

protected <T> RunnableFuture<T> newTaskFor(Runnable runnable, T value) {
    return new FutureTask<T>(runnable, value);
}

protected <T> RunnableFuture<T> newTaskFor(Callable<T> callable) {
    return new FutureTask<T>(callable);
}

public Future<?> submit(Runnable task) {
    // ...
    RunnableFuture<Object> ftask = newTaskFor(task, null);
    execute(ftask);
    return ftask;
}

public <T> Future<T> submit(Runnable task, T result) {
    // ...
    RunnableFuture<T> ftask = newTaskFor(task, result);
    execute(ftask);
    return ftask;
}

public <T> Future<T> submit(Callable<T> task) {
    // ...
    RunnableFuture<T> ftask = newTaskFor(task);
    execute(ftask);
    return ftask;
}

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