scheduleAtFixedRate vs scheduleWithFixedDelay [英] scheduleAtFixedRate vs scheduleWithFixedDelay

问题描述

<$ h $ => http：// docs的 scheduleAtFixedRate 和 scheduleWithFixedDelay 方法之间的主要区别是什么？ oracle.com/javase/8/docs/api/java/util/concurrent/ScheduledExecutorService.html\">ScheduledExecutorService ？

What's the main difference between scheduleAtFixedRate and scheduleWithFixedDelay methods of ScheduledExecutorService?

scheduler.scheduleAtFixedRate(new Runnable() {
    @Override
    public void run() {
        System.out.println("scheduleAtFixedRate:    " + new Date());
    }
}, 1, 3L , SECONDS);

scheduler.scheduleWithFixedDelay(new Runnable() {
    @Override
    public void run() {
        System.out.println("scheduleWithFixedDelay: " + new Date());
    }
}, 1, 3L , SECONDS);

它们在同一时间打印完全相同，似乎它们以完全相同的间隔执行。

they print exact the same time, seems they are executed at exact the same interval.

推荐答案

尝试在<$ c中添加 Thread.sleep（1000）; 来电$ c> run（） method ...基本上，根据前一次执行结束的时间和它（逻辑上）启动时的时间安排。

Try adding a Thread.sleep(1000); call within your run() method... Basically it's the difference between scheduling something based on when the previous execution ends and when it (logically) starts.

例如，假设我按照每小时一次的固定费率计划一次报警，每次报警都会我要一杯咖啡，需要10分钟。假设从午夜开始，我有：

For example, suppose I schedule an alarm to go off with a fixed rate of once an hour, and every time it goes off, I have a cup of coffee, which takes 10 minutes. Suppose that starts at midnight, I'd have:

00:00: Start making coffee
00:10: Finish making coffee
01:00: Start making coffee
01:10: Finish making coffee
02:00: Start making coffee
02:10: Finish making coffee

如果我安排一个小时的固定延迟，我会： / p>

If I schedule with a fixed delay of one hour, I'd have:

00:00: Start making coffee
00:10: Finish making coffee
01:10: Start making coffee
01:20: Finish making coffee
02:20: Start making coffee
02:30: Finish making coffee

您想要哪一个取决于您的任务。

Which one you want depends on your task.

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