시간을 00:00:00으로 설정

시간을 00:00:00으로 설정

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Java에서 시간을 재설정하는 데 문제가 있습니다. 주어진 날짜에 시간을 00:00:00으로 설정하고 싶습니다.

이것은 내 코드입니다.

/**
     * Resets milliseconds, seconds, minutes and hours from the provided date
     *
     * @param date
     * @return
     */
    public static Date trim(Date date) {
        Calendar calendar = Calendar.getInstance();
        calendar.setTime(date);
        calendar.set(Calendar.MILLISECOND, 0);
        calendar.set(Calendar.SECOND, 0);
        calendar.set(Calendar.MINUTE, 0);
        calendar.set(Calendar.HOUR, 0);

        return calendar.getTime();
    }

문제는 때로는 시간이 지남에 따라 12:00:00때로는 00:00:00저장된 엔터티에 대해 데이터베이스를 쿼리 할 때 07.02.2013 00:00:00실제 엔터티 시간이 저장된 12:00:00경우 쿼리가 실패 한다는 것입니다 .

알아요 12:00:00 == 00:00:00!

AppEngine을 사용하고 있습니다. 이것이 appengine 버그, 문제 또는 다른 문제입니까? 아니면 다른 것에 의존합니까?

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대신에 다른 일정 사용하여 Calendar.HOUR사용을 Calendar.HOUR_OF_DAY.

calendar.set(Calendar.HOUR_OF_DAY, 0);

Calendar.HOUR0-11을 사용하고 (AM / PM과 함께 Calendar.HOUR_OF_DAY사용) 0-23을 사용합니다.

Javadoc을 인용하려면 :

공개 정적 최종 int HOUR

오전 또는 오후의 시간을 나타내는 get 및 set의 필드 번호. HOUR는 12 시간제 (0-11)에 사용됩니다. 정오와 자정은 12가 아니라 0으로 표시됩니다. 예를 들어 오후 10 : 04 : 15.250에 HOUR는 10입니다.

과

공개 정적 최종 int HOUR_OF_DAY

하루 중 시간을 나타내는 get 및 set의 필드 번호. HOUR_OF_DAY는 24 시간 제로 사용됩니다. 예를 들어 오후 10 : 04 : 15.250에 HOUR_OF_DAY는 22입니다.

테스트 ( '현재'는 2013 년 7 월 23 일 태평양 일광 절약 시간 기준으로 현재 14:55입니다) :

public class Main
{
   static SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");

    public static void main(String[] args)
    {
        Calendar now = Calendar.getInstance();
        now.set(Calendar.HOUR, 0);
        now.set(Calendar.MINUTE, 0);
        now.set(Calendar.SECOND, 0);
        System.out.println(sdf.format(now.getTime()));
        now.set(Calendar.HOUR_OF_DAY, 0);
        System.out.println(sdf.format(now.getTime()));
    }
}

산출:

$ javac Main.java
$ java Main
2013-07-23 12:00:00
2013-07-23 00:00:00

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java.time

java.timeJava 8 이상에 내장 된 프레임 워크 사용 튜토리얼을 참조하십시오 .

import java.time.LocalTime;
import java.time.LocalDateTime;

LocalDateTime now = LocalDateTime.now(); # 2015-11-19T19:42:19.224
# start of a day
now.with(LocalTime.MIN); # 2015-11-19T00:00
now.with(LocalTime.MIDNIGHT); # 2015-11-19T00:00

시간 (시간, 분, 초 등)이 필요하지 않은 경우 LocalDate수업 사용을 고려하십시오 .

LocalDate.now(); # 2015-11-19

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다음은이 작업을 수행하는 데 사용되는 몇 가지 유틸리티 기능입니다.

/**
 * sets all the time related fields to ZERO!
 *
 * @param date
 *
 * @return Date with hours, minutes, seconds and ms set to ZERO!
 */
public static Date zeroTime( final Date date )
{
    return DateTimeUtil.setTime( date, 0, 0, 0, 0 );
}

/**
 * Set the time of the given Date
 *
 * @param date
 * @param hourOfDay
 * @param minute
 * @param second
 * @param ms
 *
 * @return new instance of java.util.Date with the time set
 */
public static Date setTime( final Date date, final int hourOfDay, final int minute, final int second, final int ms )
{
    final GregorianCalendar gc = new GregorianCalendar();
    gc.setTime( date );
    gc.set( Calendar.HOUR_OF_DAY, hourOfDay );
    gc.set( Calendar.MINUTE, minute );
    gc.set( Calendar.SECOND, second );
    gc.set( Calendar.MILLISECOND, ms );
    return gc.getTime();
}

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하나 더 자바 8 방법 :

LocalDateTime localDateTime = LocalDateTime.now().truncatedTo(ChronoUnit.HOURS);

But it's a lot more useful to edit the date that already exists.

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You would better to primarily set time zone to the DateFormat component like this:

DateFormat dateFormat = new SimpleDateFormat("HH:mm:ss");
dateFormat.setTimeZone(TimeZone.getTimeZone("GMT"));

Then you can get "00:00:00" time by passing 0 milliseconds to formatter:

String time = dateFormat.format(0);

or you can create Date object:

Date date = new Date(0); // also pass milliseconds
String time = dateFormat.foramt(date);

or you be able to have more possibilities using Calendar component but you should also set timezone as GMT to calendar instance:

Calendar calendar = Calendar.getInstance(TimeZone.getTimeZone("GMT"), Locale.US);
calendar.set(Calendar.HOUR_OF_DAY, 5);
calendar.set(Calendar.MINUTE, 37);
calendar.set(Calendar.SECOND, 27);

dateFormat.format(calendar.getTime());

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tl;dr

myJavaUtilDate                                 // The terrible `java.util.Date` class is now legacy. Use *java.time* instead.
.toInstant()                                   // Convert this moment in UTC from the legacy class `Date` to the modern class `Instant`.
.atZone( ZoneId.of( "Africa/Tunis" ) )         // Adjust from UTC to the wall-clock time used by the people of a particular region (a time zone).
.toLocalDate()                                 // Extract the date-only portion.
.atStartOfDay( ZoneId.of( "Africa/Tunis" ) )   // Determine the first moment of that date in that zone. The day does *not* always start at 00:00:00.

java.time

You are using terrible old date-time classes that were supplanted years ago by the modern java.time classes defined in JSR 310.

Date ➙ Instant

A java.util.Date represent a moment in UTC. Its replacement is Instant. Call the new conversion methods added to the old classes.

Instant instant = myJavaUtilDate.toInstant() ;

Time zone

Specify the time zone in which you want your new time-of-day to make sense.

Specify a proper time zone name in the format of Continent/Region, such as America/Montreal, Africa/Casablanca, or Pacific/Auckland. Never use the 2-4 letter abbreviation such as EST or IST as they are not true time zones, not standardized, and not even unique(!).

ZoneId z = ZoneId.of( "America/Montreal" ) ;

ZonedDateTime

Apply the ZoneId to the Instant to get a ZonedDateTime. Same moment, same point on the timeline, but different wall-clock time.

ZonedDateTime zdt = instant.atZone( z ) ;

Changing time-of-day

You asked to change the time-of-day. Apply a LocalTime to change all the time-of-day parts: hour, minute, second, fractional second. A new ZonedDateTime is instantiated, with values based on the original. The java.time classes use this immutable objects pattern to provide thread-safety.

LocalTime lt = LocalTime.of( 15 , 30 ) ;  // 3:30 PM.
ZonedDateTime zdtAtThreeThirty = zdt.with( lt ) ; 

First moment of day

But you asked specifically for 00:00. So apparently you want the first moment of the day. Beware: some days in some zones do not start at 00:00:00. They may start at another time such as 01:00:00 because of anomalies such as Daylight Saving Time (DST).

Let java.time determine the first moment. Extract the date-only portion. Then pass the time zone to get first moment.

LocalDate ld = zdt.toLocalDate() ;
ZonedDateTime zdtFirstMomentOfDay = ld.atStartOfDay( z ) ;

Adjust to UTC

If you need to go back to UTC, extract an Instant.

Instant instant = zdtFirstMomentOfDay.toInstant() ;

Instant ➙ Date

If you need a java.util.Date to interoperate with old code not yet updated to java.time, convert.

java.util.Date d = java.util.Date.from( instant ) ;

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Doing this could be easier (In Java 8)

LocalTime.ofNanoOfDay(0)

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We can set java.util.Date time part to 00:00:00 By using LocalDate class of Java 8/Joda-datetime api:

Date datewithTime = new Date() ; // ex: Sat Apr 21 01:30:44 IST 2018
LocalDate localDate = LocalDate.fromDateFields(datewithTime);
Date datewithoutTime = localDate.toDate(); // Sat Apr 21 00:00:00 IST 2018

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Another way to do this would be to use a DateFormat without any seconds:

public static Date trim(Date date) {
    DateFormat format = new SimpleDateFormat("dd.MM.yyyy");
    Date trimmed = null;
    try {
        trimmed = format.parse(format.format(date));
    } catch (ParseException e) {} // will never happen
    return trimmed;
}

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You can either do this with the following:

Calendar cal = Calendar.getInstance();
cal.set(year, month, dayOfMonth, 0, 0, 0);
Date date = cal.getTime();

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If you need format 00:00:00 in string, you should use SimpleDateFormat as below. Using "H "instead "h".

Date today = new Date();
SimpleDateFormat ft = new SimpleDateFormat("dd-MM-yyyy HH:mm:ss"); 
//not SimpleDateFormat("dd-MM-yyyy hh:mm:ss")
Calendar calendarDM = Calendar.getInstance();
calendarDM.setTime(today);
calendarDM.set(Calendar.HOUR, 0);
calendarDM.set(Calendar.MINUTE, 0);
calendarDM.set(Calendar.SECOND, 0);
System.out.println("Current Date: " + ft.format(calendarDM.getTime()));

//Result is: Current Date: 29-10-2018 00:00:00

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As Java8 add new Date functions, we can do this easily.

    // If you have instant, then:
    Instant instant1 = Instant.now();
    Instant day1 = instant1.truncatedTo(ChronoUnit.DAYS);
    System.out.println(day1); //2019-01-14T00:00:00Z

    // If you have Date, then:
    Date date = new Date();
    Instant instant2 = date.toInstant();
    Instant day2 = instant2.truncatedTo(ChronoUnit.DAYS);
    System.out.println(day2); //2019-01-14T00:00:00Z

    // If you have LocalDateTime, then:
    LocalDateTime dateTime = LocalDateTime.now();
    LocalDateTime day3 = dateTime.truncatedTo(ChronoUnit.DAYS);
    System.out.println(day3); //2019-01-14T00:00
    String format = day3.format(DateTimeFormatter.ISO_LOCAL_DATE_TIME);
    System.out.println(format);//2019-01-14T00:00:00

참고URL : https://stackoverflow.com/questions/17821601/set-time-to-000000