如何从午夜到秒获得时间
首先，这是一个我在Java 1类中坚持的简单问题。 这是一个静止的时间，我已经设置为8:49:12“今天”，我要弄清楚午夜过了多少秒，这到了午夜。 8小时49分12秒。 这是我的代码：
hour = 8; minute = 59; second = 32; System.out.println("The static time used for this program was: " + hour + ":" + minute + ":" + second); 我的问题是，我不知道如何从午夜开始计算时间。
所以基本上输出需要是：
Number of seconds since midnight: Number of seconds to midnight:
后面的空间是秒。
谢谢，请解释原因，以及如何选择如何解决这个问题。 我想学习：P
试试这个简单的数学：
System.out.println("Number of seconds since midnight:" +(second + (minute*60) + (hour*3600))); System.out.println("Number of seconds to midnight:" +((60-second) + ((60-1-minute)*60) + (24-1-hour)*3600));
final static int SEC_IN_MIN = 60; final static int SEC_IN_HOUR = SEC_IN_MIN * 60; int secFromMidnight = hour * SEC_IN_HOUR + minute * SEC_IN_MIN + second; int secToMidnight = (24 * SEC_IN_HOUR) - secFromMidnight;
鉴于时间的特殊性，您可以简单地使用Calendar API
Calendar fromMidnight = Calendar.getInstance(); fromMidnight.set(Calendar.HOUR, 0); fromMidnight.set(Calendar.MINUTE, 0); fromMidnight.set(Calendar.SECOND, 0); fromMidnight.set(Calendar.MILLISECOND, 0); Calendar toMidnight = Calendar.getInstance(); toMidnight.setTime(fromMidnight.getTime()); toMidnight.add(Calendar.DATE, 1); System.out.println(fromMidnight.getTime()); System.out.println(toMidnight.getTime()); Calendar toFromTime = Calendar.getInstance(); toFromTime.set(Calendar.HOUR, 8); toFromTime.set(Calendar.MINUTE, 59); toFromTime.set(Calendar.SECOND, 32); toFromTime.set(Calendar.MILLISECOND, 0); long secondsFromMidnight = (toFromTime.getTimeInMillis() - fromMidnight.getTimeInMillis()) / 1000; long secondsToMidnight = (toMidnight.getTimeInMillis() - toFromTime.getTimeInMillis()) / 1000; System.out.println("from = " + secondsFromMidnight + "; to " + secondsToMidnight);
哪个输出……
from = 32372; to 54028
或者你可以使用JodaTime ……
MutableDateTime now = MutableDateTime.now(); now.setMillisOfDay(0); now.setSecondOfDay(32); now.setMinuteOfDay(59); now.setHourOfDay(8); DateTime fromMidnight = now.toDateTime().toDateMidnight().toDateTime(); DateTime toMidnight = fromMidnight.plusDays(1); Duration duration = new Duration(fromMidnight, toMidnight); Duration dFromMidnight = new Duration(fromMidnight, now); System.out.println("From midnight: " + dFromMidnight.getStandardSeconds()); Duration dToMidnight = new Duration(now, toMidnight); System.out.println("To Midnight: " + dToMidnight.getStandardSeconds());
哪个输出……
From midnight: 32372 To Midnight: 54028
JAVA有一个名为TimeUnit的枚举，它可以将时间转换为任何时间单位，如下所示：
int hour = 8; int minute = 59; int second = 32; System.out.println("The static time used for this program was: " + hour + ":" + minute + ":" + second); long secInMidnight = TimeUnit.HOURS.toSeconds(24); long timeInSeconds = (TimeUnit.HOURS.toSeconds(8) + TimeUnit.MINUTES.toSeconds(minute) + second); System.out.println("\nSince midnight: " + timeInSeconds + "\nUntil midnight: " + (secInMidnight - timeInSeconds) );
由于问题的数学简单性，@ Vimal Bera的公认答案很好并且完全足够。 但是如果您仍然喜欢“正式化”（由库支持）方法而不进行“多少”计算，那么您可以在Java-8中执行此操作：
LocalTime time = LocalTime.of(8, 59, 32); System.out.println( "Seconds since midnight: " + time.get(ChronoField.SECOND_OF_DAY)); // 32372 System.out.println( "Seconds to midnight: " + (86400 - time.get(ChronoField.SECOND_OF_DAY))); // 54028
你的答案是在java.util.Calendar类中。 请参阅get（）/ set（）方法： http ： //docs.oracle.com/javase/6/docs/api/java/util/Calendar.html
import java.util.Calendar; public class HelloWorld{ public static void main(String []args){ int hour = 8; int minute = 59; int second = 32; System.out.println("The static time used for this program was: " + hour + ":" + minute + ":" + second); final Calendar currentTime = Calendar.getInstance(); currentTime.set(2013,Calendar.SEPTEMBER,24,8,59,32); final Calendar midNight = Calendar.getInstance(); midNight.clear(); midNight.set(2013, Calendar.SEPTEMBER, 25); System.out.println(.001*(midNight.getTimeInMillis() - currentTime.getTimeInMillis())); }
}
考虑使用Calendar和/或尝试JodaTime库