为什么不能构造一个由DelayQueue支持的ThreadPoolExecutor？ [英] Why can't I construct a ThreadPoolExecutor backed by a DelayQueue?

问题描述

我正在尝试创建一个ThreadPoolExecutor：

I'm trying to create a ThreadPoolExecutor:

// Thingy implements Delayed and Runnable
ExecutorService executor = new ThreadPoolExecutor(1, 1, 0l, TimeUnit.SECONDS, new DelayQueue<Thingy>());

编译器说找不到符号：

symbol  : constructor ThreadPoolExecutor(int,int,long,java.util.concurrent.TimeUnit,java.util.concurrent.DelayQueue<Thingy>)

但我不明白- DelayQueue 实现了 BlockingQueue ，所以我不应该使用此构造函数？

but I don't understand — DelayQueue implements BlockingQueue, so shouldn't I be able to use this constructor?

推荐答案

这是一个泛型问题。您不能使用 DelayQueue< Thingy> ，它必须是 DelayQueue< Runnable> 作为 ThreadPoolExecutor 构造函数未声明为接受 Runnable 子类型的队列。

This is a generics problem. You can't use DelayQueue<Thingy>, it has to be DelayQueue<Runnable> as the ThreadPoolExecutor constructor is not declared to accept queues of sub-types of Runnable.

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