在Java中运行代码x秒钟? [英] Run code for x seconds in Java?

问题描述

我想编写一个Java while循环，该循环将迭代15秒.我想到的一种方法是存储当前系统时间+ 15秒，然后将其与while循环签名中的当前时间进行比较.

I'd like to write a java while loop that will iterate for 15 seconds. One way I thought to do this would be to store the current system time + 15sec and then compare that to the current time in the while loop signature.

有更好的方法吗?

推荐答案

此方案的设计取决于您要在15s内执行的操作.两种最合理的情况是每X进行15秒"或等待X发生或15秒钟，以较早者为准"，这将导致代码截然不同.

The design of this depends on what you want doing for 15s. The two most plausible cases are "do this every X for 15s" or "wait for X to happen or 15s whichever comes sooner", which will lead to very different code.

Thread.sleep(15000 )

这不会重复，但是如果您不希望执行15秒钟的操作，效率会更高(在执行任何操作时浪费的CPU更少).

This doesn't iterate, but if you want to do nothing for 15s is much more efficient (it wastes less CPU on doing nothing).

如果您真的想循环15秒，那么您的解决方案就可以了，只要您的代码不会花费太长时间即可.像这样:

If you really want to loop for 15s then your solution is fine, as long as your code doesn't take too long. Something like:

long t= System.currentTimeMillis();
long end = t+15000;
while(System.currentTimeMillis() < end) {
  // do something
  // pause to avoid churning
  Thread.sleep( xxx );
}

等待15秒或其他情况

如果您希望代码在15s后被中断，无论执行什么操作，都需要一个多线程解决方案.查看 java.util.concurrent 获取大量有用的对象.大多数锁定方法(如wait())都有一个超时参数. 信号量可能完全可以您需要什么.

Wait for 15s or some other condition

If you want your code to be interrupted after exactly 15s whatever it is doing you'll need a multi-threaded solution. Look at java.util.concurrent for lots of useful objects. Most methods which lock (like wait() ) have a timeout argument. A semaphore might do exactly what you need.

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