Android Java：如何减去两次？

Android Java : How to subtract two times?

提问by Nezir

I use some kind of stopwatch in my project and I have

我在我的项目中使用了某种秒表，我有

start time ex: 18:40:10 h
stop time  ex: 19:05:15 h

I need a result from those two values like final time = stop - start

我需要这两个值的结果，例如 final time = stop - start

I found some examples but they all are very confusing .

我找到了一些例子，但它们都非常令人困惑。

Is there any simple solution ?

有什么简单的解决办法吗？

采纳答案by John

If you have strings you need to parse them into a java.util.Date using java.text.SimpleDateFormat. Something like:

如果您有字符串，则需要使用 java.text.SimpleDateFormat 将它们解析为 java.util.Date。就像是：

        java.text.DateFormat df = new java.text.SimpleDateFormat("hh:mm:ss");
        java.util.Date date1 = df.parse("18:40:10");
        java.util.Date date2 = df.parse("19:05:15");
        long diff = date2.getTime() - date1.getTime();

Here diff is the number of milliseconds elapsed between 18:40:10 and 19:05:15.

这里的 diff 是 18:40:10 和 19:05:15 之间经过的毫秒数。

EDIT 1:

编辑 1：

Found a method online for this (at http://www.javaworld.com/javaworld/jw-03-2001/jw-0330-time.html?page=2):

在网上找到了一个方法（在http://www.javaworld.com/javaworld/jw-03-2001/jw-0330-time.html?page=2）：

  int timeInSeconds = diff / 1000;
  int hours, minutes, seconds;
  hours = timeInSeconds / 3600;
  timeInSeconds = timeInSeconds - (hours * 3600);
  minutes = timeInSeconds / 60;
  timeInSeconds = timeInSeconds - (minutes * 60);
  seconds = timeInSeconds;

EDIT 2:

编辑2：

If you want it as a string (this is a sloppy way, but it works):

如果你想要它作为一个字符串（这是一种草率的方式，但它有效）：

String diffTime = (hours<10 ? "0" + hours : hours) + ":" + (minutes < 10 ? "0" + minutes : minutes) + ":" + (seconds < 10 ? "0" + seconds : seconds) + " h";

EDIT 3:

编辑 3：

If you want the milliseconds just do this

如果你想要毫秒就这样做

long timeMS = diff % 1000;

You can then divide that by 1000 to get the fractional part of your seconds.

然后，您可以将其除以 1000 以获得秒的小数部分。

回答by Thierry-Dimitri Roy

Assuming you are using java.util.Date:

假设您使用的是java.util.Date：

long totalTime = endDate.getTime() - startDate.getTime();

The result will be the total time in milliseconds.

结果将以毫秒为单位的总时间。

回答by Momen Ali

Try this answer it will help you a lot

试试这个答案，它会对你有很大帮助

from here

从这里

In this answer, you will find subtract to two times discarding the day and month and year.

在这个答案中，您会发现减去两次丢弃日、月和年。

it gives you the number of minutes you will spend until you reach the second Time value.

它为您提供在达到第二个时间值之前您将花费的分钟数。

回答by Ole V.V.

I am providing the modern answer.

我正在提供现代答案。

java.time and ThreeTenABP

java.time 和 ThreeTenABP

    DateTimeFormatter timeFormatter = DateTimeFormatter.ofPattern("H:mm:ss 'h'");

    String startTimeString = "18:40:10 h";
    String stopTimeString = "19:05:15 h";

    LocalTime startTime = LocalTime.parse(startTimeString, timeFormatter);
    LocalTime stopTime = LocalTime.parse(stopTimeString, timeFormatter);

    if (stopTime.isBefore(startTime)) {
        System.out.println("Stop time must not be before start time");
    } else {
        Duration difference = Duration.between(startTime, stopTime);

        long hours = difference.toHours();
        difference = difference.minusHours(hours);
        long minutes = difference.toMinutes();
        difference = difference.minusMinutes(minutes);
        long seconds = difference.getSeconds();

        System.out.format("%d hours %d minutes %d seconds%n", hours, minutes, seconds);
    }

Output from this example is:

这个例子的输出是：

0 hours 25 minutes 5 seconds

0 小时 25 分 5 秒

The other answers were good answers in 2010. Today avoid the classes DateFormat, SimpleDateFormatand Date. java.time, the modern Java date and time API, is so much nicer to work with.

其他答案是 2010 年的好答案。今天避免上课DateFormat，SimpleDateFormat和Date。java.time 是现代 Java 日期和时间 API，使用起来要好得多。

But doesn't it require API level 26?

但是它不需要 API 级别 26 吗？

No, using java.time works nicely on older and newer Android devices. It just requires at least Java 6.

不，在较旧和较新的 Android 设备上使用 java.time 效果很好。它只需要至少Java 6。

• In Java 8 and later and on newer Android devices (from API level 26) the modern API comes built-in.
• In non-Android Java 6 and 7 get the ThreeTen Backport, the backport of the modern classes (ThreeTen for JSR 310; see the links at the bottom).
• On (older) Android use the Android edition of ThreeTen Backport. It's called ThreeTenABP. And make sure you import the date and time classes from org.threeten.bpwith subpackages.

• 在 Java 8 及更高版本以及更新的 Android 设备（从 API 级别 26）中，现代 API 是内置的。
• 在非 Android Java 6 和 7 中获得 ThreeTen Backport，现代类的 backport（ThreeTen for JSR 310；请参阅底部的链接）。
• 在（较旧的）Android 上使用 ThreeTen Backport 的 Android 版本。它被称为 ThreeTenABP。并确保从org.threeten.bp子包中导入日期和时间类。

Links

链接

• Oracle tutorial: Date Timeexplaining how to use java.time.
• Java Specification Request (JSR) 310, where java.timewas first described.
• ThreeTen Backport project, the backport of java.timeto Java 6 and 7 (ThreeTen for JSR-310).
• ThreeTenABP, Android edition of ThreeTen Backport
• Question: How to use ThreeTenABP in Android Project, with a very thorough explanation.

• Oracle 教程：解释如何使用 java.time 的日期时间。
• Java 规范请求 (JSR) 310，java.time首先描述的地方。
• ThreeTen Backport 项目，java.time向 Java 6 和 7 (ThreeTen for JSR-310)的向后移植。
• ThreeTenABP, ThreeTen Backport安卓版
• 问题：如何在Android项目中使用ThreeTenABP，讲解很透彻。

回答by Frischling

Today, with newer Java (no idea, at what Android version this works):

今天，使用更新的 Java（不知道，它在哪个 Android 版本上有效）：

Instant before = Instant.now();
// do stuff

Duration.between(before, Instant.now()).getSeconds()

The clumsy java ways from olden days are now gone.

过去笨拙的 Java 方式现在已经一去不复返了。