How to obtain the start time and end time of a day?

Question

How to obtain the start time and end time of a day?

code like this is not accurate:

 private Date getStartOfDay(Date date) {     Calendar calendar = Calendar.getInstance();     int year = calendar.get(Calendar.YEAR);     int month = calendar.get(Calendar.MONTH);     int day = calendar.get(Calendar.DATE);     calendar.set(year, month, day, 0, 0, 0);     return calendar.getTime(); }  private Date getEndOfDay(Date date) {     Calendar calendar = Calendar.getInstance();     int year = calendar.get(Calendar.YEAR);     int month = calendar.get(Calendar.MONTH);     int day = calendar.get(Calendar.DATE);     calendar.set(year, month, day, 23, 59, 59);     return calendar.getTime(); } 

It is not accurate to the millisecond.

Answer 1

Java 8

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public static Date atStartOfDay(Date date) {     LocalDateTime localDateTime = dateToLocalDateTime(date);     LocalDateTime startOfDay = localDateTime.with(LocalTime.MIN);     return localDateTimeToDate(startOfDay); }  public static Date atEndOfDay(Date date) {     LocalDateTime localDateTime = dateToLocalDateTime(date);     LocalDateTime endOfDay = localDateTime.with(LocalTime.MAX);     return localDateTimeToDate(endOfDay); }  private static LocalDateTime dateToLocalDateTime(Date date) {     return LocalDateTime.ofInstant(date.toInstant(), ZoneId.systemDefault()); }  private static Date localDateTimeToDate(LocalDateTime localDateTime) {     return Date.from(localDateTime.atZone(ZoneId.systemDefault()).toInstant()); } 

Update: I've added these 2 methods to my Java Utility Classes here

• DateUtils.atStartOfDay
• DateUtils.atEndOfDay

It is in the Maven Central Repository at:

<dependency>   <groupId>com.github.rkumsher</groupId>   <artifactId>utils</artifactId>   <version>1.3</version> </dependency> 

Java 7 and Earlier

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With Apache Commons

public static Date atEndOfDay(Date date) {     return DateUtils.addMilliseconds(DateUtils.ceiling(date, Calendar.DATE), -1); }  public static Date atStartOfDay(Date date) {     return DateUtils.truncate(date, Calendar.DATE); } 

Without Apache Commons

public Date atEndOfDay(Date date) {     Calendar calendar = Calendar.getInstance();     calendar.setTime(date);     calendar.set(Calendar.HOUR_OF_DAY, 23);     calendar.set(Calendar.MINUTE, 59);     calendar.set(Calendar.SECOND, 59);     calendar.set(Calendar.MILLISECOND, 999);     return calendar.getTime(); }  public Date atStartOfDay(Date date) {     Calendar calendar = Calendar.getInstance();     calendar.setTime(date);     calendar.set(Calendar.HOUR_OF_DAY, 0);     calendar.set(Calendar.MINUTE, 0);     calendar.set(Calendar.SECOND, 0);     calendar.set(Calendar.MILLISECOND, 0);     return calendar.getTime(); }