What are the common time-related methods in Java

This article mainly introduces "what are the time-related methods commonly used in Java". In daily operation, I believe that many people have doubts about the time-related methods commonly used in Java. The editor consulted all kinds of materials and sorted out simple and easy-to-use methods of operation. I hope it will be helpful for you to answer the doubts about "what are the common time-related methods in Java?" Next, please follow the editor to study!

1. How to get the current time: public static void main (String [] args) {/ / Date Date now = new Date (); System.out.println (now); / / the time of java8 LocalDateTime localDateTime = LocalDateTime.now (); System.out.println (localDateTime); Calendar calendar = Calendar.getInstance (); Date time = calendar.getTime (); System.out.println (time) System.out.println (year + calendar.get (Calendar.YEAR)); System.out.println (month + (calendar.get (Calendar.MONTH) + 1)); / / joda time DateTime dateTime = DateTime.now (); System.out.println (dateTime);}

You can use Date LocalDatetime Calendar Datetime to get the current time

2. Get public static void main on the nth day of the month (String [] args) {/ / it is recommended to use Calendar to set Calendar calendar = Calendar.getInstance (); / 16 calendar.set (Calendar.DAY_OF_MONTH, 16); System.out.println (calendar.getTime ()); / / 16 DateTime now = DateTime.now (); DateTime dateTime = now.withDayOfMonth (16); System.out.println (dateTime) / / 14 LocalDateTime localDateTime = LocalDateTime.now (); System.out.println (localDateTime.withDayOfMonth (14)); / / January 11 System.out.println (localDateTime.withMonth (1). WithDayOfMonth (11));} III. Format to string ```/ / use SimpleDateFormatSimpleDateFormat format = new SimpleDateFormat ("yyyy-MM-dd HH:mm:ss"); System.out.println (format.format (new Date (); / / use CalendarCalendar calendar = Calendar.getInstance () System.out.println (String.format ("% s year% s month% s day% s minutes% s seconds", calendar.get (Calendar.YEAR), calendar.get (Calendar.MONTH) + 1, calendar.get (Calendar.DAY_OF_MONTH), calendar.get (Calendar.HOUR_OF_DAY), calendar.get (Calendar.MINUTE), calendar.get (Calendar.SECOND)); LocalDateTime now = LocalDateTime.now () String str = now.format (DateTimeFormatter.ofPattern ("yyyy-MM-dd HH:mm:ss")); System.out.println (str); ```4. Add and subtract time (in seconds, hours, etc.) public static void main (String [] args) {Date now = new Date (); / / add one hour long time = now.getTime () + (60 * 60 * 1000); System.out.println (new Date (time)) / * cn.hutool hutool-all 5.7.14 * / / introduce Hutool plus one hour System.out.println (DateUtil.offset (now, DateField.HOUR, 1)); / / minus one hour System.out.println (DateUtil.offset (now, DateField.HOUR,-1)); LocalDateTime localDateTime = LocalDateTime.now (); System.out.println ("plus one hour" + localDateTime.plusHours (1)) System.out.println ("minus one hour" + localDateTime.minusHours (1)); DateTime dateTime = DateTime.now (); System.out.println (dateTime.plusHours (1)); System.out.println (dateTime.minusHours (1));}

Both LocalDateTime and DateTime have their own ways to increase and decrease time

5. Obtain the age public static void main (String [] args) {/ / time 1990-12-05 DateTime birthDay = DateTime.now (). WithYear (1990). WithMonthOfYear (10). WithDayOfMonth (23); System.out.println (birthDay); / / the difference between years will be compared with the month and date, such as Years years = Years.yearsBetween (birthDay, new DateTime (); System.out.println (years)) System.out.println (years.getYears ());}

Birthdays can also be obtained by subtracting years and comparing months and days.

6. Judge whether public static void main (String [] args) {DateTime now = DateTime.now (); DateTime start1 = now; DateTime end1 = now.plusMinutes (1); DateTime start2 = now.plusSeconds (50); DateTime end2 = now.plusMinutes (2); Interval interval1 = new Interval (start1, end1); Interval interval2 = new Interval (start2, end2); System.out.println (interval1.overlaps (interval2)) System.out.println (start1.getMillis () < end2.getMillis () & & start2.getMillis () < end1.getMillis ()); 7. Find two intervals public static void main (String [] args) {DateTime now = DateTime.now (); / / start time Date startTime = now.toDate (); / / end time Date endTime = now.plusHours (1). ToDate () / / 1 hour System.out.println ("interval between start time and end time:" + DateUtil.between (startTime, endTime, DateUnit.SECOND)); long time = (endTime.getTime ()-startTime.getTime ()) / 1000; System.out.println (time);} VIII. Conversion between UTC time and Beijing time public static void main (String [] args) throws ParseException {Date now = new Date (); Date utcDate = bj2UTC (now) / / utc time System.out.println (utcDate); / / Beijing time System.out.println (utc2BJ (utcDate)); DateTime dateTime = DateTime.now (). WithDayOfMonth (1). WithHourOfDay (0). WithMinuteOfHour (0). WithsecondOfMinute (0); System.out.println (dateTime); System.out.println (bj2UTC (dateTime.toDate ();} public static Date bj2UTC (Date date) {if (date = = null) {return null } LocalDateTime localDateTime = LocalDateTime.ofInstant (date.toInstant (), ZoneId.of ("- 8")); return Date.from (localDateTime.atOffset (ZoneOffset.UTC). ToInstant ());} public static Date utc2BJ (Date date) {if (date = = null) {return null;} LocalDateTime localDateTime = LocalDateTime.ofInstant (date.toInstant (), ZoneId.of ("+ 8")); return Date.from (localDateTime.atOffset (ZoneOffset.UTC). ToInstant ());}

Beijing time = UTC+8

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