在Java 8中使用TemporalAmount或TemporalUnit有什么区别？ [英] What is the difference of using TemporalAmount or TemporalUnit in Java 8?

问题描述

我在Java 8中编写了一些使用时间算法的代码。
我意识到我可以在不同的方面实施。让我们看看下面的简单代码。当然它是相同的结果，但我混淆了哪种方式主要应用或最有效地在Java 8中进行算术运算？

I write some piece of code in Java 8 which use time arithmetic. I realize that I can implement in differentways. Lets look at simple code below. Of course it is the same result but I confused which way is mostly applied or most efficient to make arithmetic operations in Java 8 ?

LocalTime time = LocalTime.now();
// 1st way
LocalTime plusOp = time.plus(Duration.ofMinutes(10L));
// 2nd way
LocalTime plusOp2 = time.plus(10L, ChronoUnit.MINUTES);
System.out.println(plusOp);
System.out.println(plusOp2);
// 3. way simply
 time.plusMinutes(10L);

提前致谢。

推荐答案

持续时间只能处理固定时间段，例如小时，分钟，秒，天（其中）假设每天24小时）。你不能在持续时间中使用月，因为一个月的长度不一。

Duration can only handle fixed-length periods, such as "hours", "minutes", "seconds", "days" (where it assumes exactly 24 hours per day). You can't use "months" with Duration, because a month varies in length.

期间 - 另一个常见的 TemporalAmount 实施 - 分别代表年，月和日。

Period - the other common TemporalAmount implementation - represents years, months and days separately.

我个人建议：

• 如果您事先知道该单位，请使用相应的 plusXxx 方法，例如 time.plusMinutes（10）。这很容易阅读。


• 当您尝试表示逻辑日历金额时，请使用期间


• 当您尝试表示固定长度金额时，请使用持续时间

• When you know the unit beforehand, use the appropriate plusXxx method, e.g. time.plusMinutes(10). That's about as easy to read as it gets.
• When you're trying to represent "logical" calendar amounts, use Period
• When you're trying to represent "fixed length" amounts, use Duration

以下是期间和期限可能不同的示例

Here's an example of where Period and Duration can differ:

import java.time.*;

public class Test {
    public static void main(String[] args) {
        ZoneId zone = ZoneId.of("Europe/London");
        // At 2015-03-29T01:00:00Z, Europe/London goes from UTC+0 to UTC+1
        LocalDate transitionDate = LocalDate.of(2015, 3, 29);
        ZonedDateTime start = ZonedDateTime.of(transitionDate, LocalTime.MIDNIGHT, zone);
        ZonedDateTime endWithDuration = start.plus(Duration.ofDays(1));
        ZonedDateTime endWithPeriod = start.plus(Period.ofDays(1));
        System.out.println(endWithDuration); // 2015-03-30T01:00+01:00[Europe/London]
        System.out.println(endWithPeriod);   // 2015-03-30T00:00+01:00[Europe/London]
    }
}

在你真正需要之前我不会担心效率 - 在这一点上你应该有一个基准，这样你就可以测试不同的选项。

I wouldn't worry about the efficiency until you really need to - at which point you should have a benchmark so you can test different options.

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