鉴于今天的时间，例如下午2:24，如何让它到下午2:30？
同样，如果时间是下午2:17，我该如何让它到下午2:15？
答案 0 :(得分：76)
您需要使用modulo截断四分之一小时：
Date whateverDateYouWant = new Date();
Calendar calendar = Calendar.getInstance();
calendar.setTime(whateverDateYouWant);
int unroundedMinutes = calendar.get(Calendar.MINUTE);
int mod = unroundedMinutes % 15;
calendar.add(Calendar.MINUTE, mod < 8 ? -mod : (15-mod));
正如EJP所指出的，这也没关系（替换最后一行，只有在日历为lenient时才有效）：
calendar.set(Calendar.MINUTE, unroundedMinutes + mod);
如果您想要准确，您还必须截断较小的字段：
calendar.set(Calendar.SECOND, 0);
calendar.set(Calendar.MILLISECOND, 0);
您还可以使用DateUtils.truncate()中的Apache Commons / Lang执行此操作：
calendar = DateUtils.truncate(calendar, Calendar.MINUTE);
答案 1 :(得分：16)
如果您只想向下舍入，则使用 Java Time API 是一个更具可读性的版本：
import Rx from "rxjs";
import {combineEpics} from "redux-observable";
import client from "../../integration/rest/client";
import {showLoading, hideLoading} from 'react-redux-loading-bar'
import * as types from "./actionTypes";
import * as actions from "./actions";
const fetchEpic = action$ =>
action$.ofType(types.FETCH)
.mergeMap(action =>
Rx.Observable.of(showLoading()).merge(
client({method: 'GET', path: '/api'})
.mergeMap(payload => Rx.Observable.of(actions.fetchSuccess(payload), hideLoading()))
.catch(error => Rx.Observable.of(actions.fetchFailure(error), hideLoading()))
)
);
export default combineEpics(fetchEpic);
输出：
2016-11-04T10：58：10.228
2016-11-04T10：45：00
答案 2 :(得分：9)
很简单，找到自1970年以来的季度数量为双倍，将其四舍五入并乘以15分钟：
long timeMs = System.System.currentTimeMillis();
long roundedtimeMs = Math.round( (double)( (double)timeMs/(double)(15*60*1000) ) ) * (15*60*1000) );
使用该对象设置日期或日历对象。
答案 3 :(得分：8)
通过上面的答案，你最终得到了所有有趣的代码来处理溢出到几小时，几天等。
我会使用自纪元以来的ms时间。
添加7.5分钟或7.5x60x1000 = 450000
并截断为900000的倍数
new Date(900000 * ((date.getTime() + 450000) / 900000))
这是有效的，因为ms时间开始的时间恰好是00:00:00。而且由于世界上所有时区都以15分钟的步长变化，这不会影响四舍五入。
（哎呀，我得了0太多，忘记了一些重要的括号：现在还为时尚早）
答案 4 :(得分：6)
Java 8的注释实现。接受任意舍入单位和增量：
public static ZonedDateTime round(ZonedDateTime input, TemporalField roundTo, int roundIncrement) {
/* Extract the field being rounded. */
int field = input.get(roundTo);
/* Distance from previous floor. */
int r = field % roundIncrement;
/* Find floor and ceiling. Truncate values to base unit of field. */
ZonedDateTime ceiling =
input.plus(roundIncrement - r, roundTo.getBaseUnit())
.truncatedTo(roundTo.getBaseUnit());
ZonedDateTime floor =
input.plus(-r, roundTo.getBaseUnit())
.truncatedTo(roundTo.getBaseUnit());
/*
* Do a half-up rounding.
*
* If (input - floor) < (ceiling - input)
* (i.e. floor is closer to input than ceiling)
* then return floor, otherwise return ceiling.
*/
return Duration.between(floor, input).compareTo(Duration.between(input, ceiling)) < 0 ? floor : ceiling;
}
来源：我自己
答案 5 :(得分：5)
精彩的帖子，非常感谢你们！这正是我所需要的：）
这是我基于工作的代码。
我的用例是“鉴于它是上午11:47，我想设置两个日期，象征着当前的5分钟帧：上午11:45和上午11:50”
Calendar calendar = Calendar.getInstance();
calendar.set(Calendar.SECOND, 0);
calendar.set(Calendar.MILLISECOND, 0);
int modulo = calendar.get(Calendar.MINUTE) % 5;
if(modulo > 0) {
calendar.add(Calendar.MINUTE, -modulo);
}
myObject.setStartDate(calendar.getTime());
calendar.add(Calendar.MINUTE, 5);
myObject.setDueDate(calendar.getTime());
答案 6 :(得分：1)
您可以使用这个简单的代码...
int mode = min % 15;
if (mode > 15 / 2) {
min = 15 - mode;
} else {
min = 0 - mode;
}
cal.add(Calendar.MINUTE, min);
答案 7 :(得分：1)
也许您可以使用实用程序库来操作日期，例如，您有一个圆形方法，对您有用：
这是代码中的一个例子：
FastDateFormat formatter = DateFormatUtils.ISO_DATETIME_TIME_ZONE_FORMAT;
Date now = new Date();
System.out.println("now = " + formatter.format(now));
// Get nearest second
Date nearestSecond = DateUtils.round(now, Calendar.SECOND);
System.out.println("nearestSecond = " + formatter.format(nearestSecond));
// Get nearest minute
Date nearestMinute = DateUtils.round(now, Calendar.MINUTE);
System.out.println("nearestMinute = " + formatter.format(nearestMinute));
// Get nearest hour
Date nearestHour = DateUtils.round(now, Calendar.HOUR);
System.out.println("nearestHour = " + formatter.format(nearestHour));
答案 8 :(得分：1)
public static Date getCurrentDateTimeWithQuarterRounding() {
final Calendar calendar = new GregorianCalendar();
calendar.setTime(new Date());
calendar.set(Calendar.MILLISECOND, 0);
calendar.set(Calendar.SECOND, 0);
final int minutes = calendar.get(Calendar.MINUTE);
if (minutes < 15) {
calendar.set(Calendar.MINUTE, 0);
} else if (minutes >= 45) {
calendar.set(Calendar.MINUTE, 45);
} else if (minutes < 30) {
calendar.set(Calendar.MINUTE, 15);
} else {
calendar.set(Calendar.MINUTE, 30);
}
return calendar.getTime();
}
答案 9 :(得分：1)
如果您需要将时间四舍五入到以 Duration 形式提供的最接近的任意级别：
static long truncateTo(long timeEpochMillis, Duration d) {
long x = timeEpochMillis / d.toMillis();
return x * d.toMillis();
}
答案 10 :(得分：1)
我建议您使用 modern date-time API*:
import java.time.LocalDate;
import java.time.LocalTime;
import java.time.ZoneId;
import java.time.ZonedDateTime;
import java.time.temporal.ChronoUnit;
import java.util.stream.Stream;
public class Main {
public static void main(String[] args) {
// Change it to the applicable ZoneId e.g. ZoneId.of("Asia/Kolkata")
ZoneId zoneId = ZoneId.systemDefault();
Stream.of(
"10:00",
"10:05",
"10:10",
"10:15",
"10:20",
"10:25",
"10:30"
).forEach(t -> System.out.println(roundToNearestQuarter(t, zoneId)));
}
static ZonedDateTime roundToNearestQuarter(String strTime, ZoneId zoneId) {
LocalTime time = LocalTime.parse(strTime);
return LocalDate.now()
.atTime(time)
.atZone(zoneId)
.truncatedTo(ChronoUnit.HOURS)
.plusMinutes(15 * Math.round(time.getMinute() / 15.0));
}
}
输出：
2021-04-02T10:00+01:00[Europe/London]
2021-04-02T10:00+01:00[Europe/London]
2021-04-02T10:15+01:00[Europe/London]
2021-04-02T10:15+01:00[Europe/London]
2021-04-02T10:15+01:00[Europe/London]
2021-04-02T10:30+01:00[Europe/London]
2021-04-02T10:30+01:00[Europe/London]
如果您只是在寻找时间，请使用 ZonedDateTime#toLocalTime 从获得的 LocalTime 中获取 ZonedDateTime。
从 Trail: Date Time 了解有关现代日期时间 API 的更多信息。
* java.util 日期时间 API 及其格式化 API SimpleDateFormat 已过时且容易出错。建议完全停止使用它们并切换到现代日期时间 API。出于任何原因，如果您必须坚持使用 Java 6 或 Java 7，您可以使用 ThreeTen-Backport，它将大部分 java.time 功能向后移植到 Java 6 和 7。如果您正在工作对于 Android 项目并且您的 Android API 级别仍然不符合 Java-8，请检查 Java 8+ APIs available through desugaring 和 How to use ThreeTenABP in Android Project。
答案 11 :(得分：0)
如果您有分钟，可以使用以下功能对它们进行舍入：
int minutes = i % 15 < 8 ? i / 15 * 15 : (i / 15 + 1) * 15;
答案 12 :(得分：0)
minutes = (int) (Math.round(minutes / 15.0) * 15.0);
答案 13 :(得分：0)
使用Java Instant API的另一种替代方法。
Instant instant = Instant.now();
int intervalInMinutes = 10;
instant.truncatedTo(ChronoUnit.MINUTES).minus(instant.atZone(ZoneId.of("UTC")).getMinute() % (1* intervalInMinutes),ChronoUnit.MINUTES);
答案 14 :(得分：0)
使用以下函数将分钟取整到上一个季度getRecentQuater():Date，getSysDate_LastQuarterMins("dd.MM.yyyy HH:mm:ss"):String：转换LocalDateTime to Date
public static Date getRecentQuater() {
LocalDateTime time = LocalDateTime.now();
LocalDateTime lastQuarter = time.truncatedTo(ChronoUnit.HOURS).plusMinutes(getLastQuarterValue(time.getMinute()));
System.out.println("lastQuarter LocalDateTime: " + lastQuarter);
Date date = Date.from(lastQuarter.atZone(ZoneId.systemDefault()).toInstant());
System.out.println("lastQuarter Date: " + lastQuarter);
return date;
}
public static String getSysDate_LastQuarterMins(String dateFormat) {
Date date = getRecentQuater();
SimpleDateFormat ft = new SimpleDateFormat (dateFormat);
String sysDate_RoundMin = ft.format(date);
System.out.println("getSysDate_LastQuarterMins() LocalDateTime : "+sysDate_RoundMin);
return sysDate_RoundMin;
}
getSysDate_LastQuarterMins() : Mon Jan 20 17:30:00 CET 2020
public static Date getSysDate_LastQuarterMins() {
Calendar cal = Calendar.getInstance();
cal.setTime( new Date(System.currentTimeMillis()) );
int min = cal.get(Calendar.MINUTE);
cal.set(Calendar.MINUTE, getLastQuarterValue(min));
cal.set(Calendar.SECOND, 00);
Date lastQuarter = cal.getTime();
System.out.println("getSysDate_LastQuarterMins() Calendar : "+lastQuarter);
return lastQuarter;
}
您可以从以下功能中找到LastQuarter值取整值，该功能在函数调用diaplayLastQuarter_RoundValue(min)上提供了一些输出：
Min: 10, LastQuarter: 0, Round: 15
Min: 24, LastQuarter: 15, Round: 30
Min: 36, LastQuarter: 30, Round: 30
Min: 37, LastQuarter: 30, Round: 30
Min: 38, LastQuarter: 30, Round: 45
Min: 39, LastQuarter: 30, Round: 45
Min: 44, LastQuarter: 30, Round: 45
Min: 57, LastQuarter: 45, Round: 00 [57, 07:45:00, 08:00:00]
public static void diaplayLastQuarter_RoundValue(int minutes) {
System.out.format("Min: %2d, LastQuarter: %2d, Round: %2d\n",
minutes, getLastQuarterValue(minutes), getRoundValue(minutes));
}
public static int getLastQuarterValue(int minutes) {
int min = 15 * (minutes / 15);
//System.out.println("Min: "+minutes+", getLastQuarterValue : "+ min);
return min;
}
public static int getRoundValue(int minutes) {
getLastQuarterValue(minutes);
int minRound = (int) (Math.round(minutes / 15.0) * 15.0);
//System.out.println("Min: "+minutes+", getRoundValue : "+minRound);
return minRound;
}
答案 15 :(得分：0)
如果有人有兴趣获得最近的（向上或向下）五或十五个间隔，我使用模块制作了一个函数来完成这项工作。
public LocalTime roundToTheNearestInterval(LocalTime original, Integer measurementInterval) {
LocalTime nearest;
int mod;
switch (measurementInterval) {
case 5:
mod = original.getMinute() % 5;
nearest = mod >= 3 ?
original.truncatedTo(ChronoUnit.HOURS)
.plusMinutes((long) 5 * (original.getMinute() / 5) + 5) :
original.truncatedTo(ChronoUnit.HOURS)
.plusMinutes((long) 5 * (original.getMinute() / 5));
break;
case 15:
mod = original.getMinute() % 15;
nearest = mod >= 8 ?
original.truncatedTo(ChronoUnit.HOURS)
.plusMinutes((long) 15 * (original.getMinute() / 15) + 15) :
original.truncatedTo(ChronoUnit.HOURS)
.plusMinutes((long) 15 * (original.getMinute() / 15));
break;
default:
nearest = original;
}
return nearest;
}
你可以用这个单元测试试试
@Test
void roundToTheNearestInterval() {
//given
LocalTime originalTime1 = LocalTime.of(6, 31, 15);
LocalTime originalTime2 = LocalTime.of(19, 13, 42);
LocalTime originalTime3 = LocalTime.of(6, 37, 11);
LocalTime originalTime4 = LocalTime.of(19, 40, 34);
Integer measurementInterval_5min = 5;
Integer measurementInterval_15min = 15;
MyService myService = new MyService();
//when
LocalTime rounded1_5min = myService.roundToTheNearestInterval(originalTime1, measurementInterval_5min);
LocalTime rounded2_5min = myService.roundToTheNearestInterval(originalTime2, measurementInterval_5min);
LocalTime rounded1_15min = myService.roundToTheNearestInterval(originalTime3, measurementInterval_15min);
LocalTime rounded2_15min = myService.roundToTheNearestInterval(originalTime4, measurementInterval_15min);
//then
assertEquals(LocalTime.of(6, 30, 0), rounded1_5min);
assertEquals(LocalTime.of(19, 15, 0), rounded2_5min);
assertEquals(LocalTime.of(6, 30, 0), rounded1_15min);
assertEquals(LocalTime.of(19, 45, 0), rounded2_15min);
}