Date & Time

https://docs.oracle.com/javase/tutorial/datetime/TOC.html

LocalDate today = LocalDate.now();

LocalDate dateOfBirth = LocalDate.of(2012, Month.MAY, 14);
LocalDate firstBirthday = dateOfBirth.plusYears(1); 

LocalTime thisSec;

for (;;) {
    thisSec = LocalTime.now();
    display(thisSec.getHour(), thisSec.getMinute(), thisSec.getSecond());
} 

System.out.printf("now: %s%n", LocalDateTime.now());

System.out.printf("Apr 15, 1994 @ 11:30am: %s%n",
                  LocalDateTime.of(1994, Month.APRIL, 15, 11, 30));

System.out.printf("now (from Instant): %s%n",
                  LocalDateTime.ofInstant(Instant.now(), ZoneId.systemDefault()));

System.out.printf("6 months from now: %s%n",
                  LocalDateTime.now().plusMonths(6));

System.out.printf("6 months ago: %s%n",
                  LocalDateTime.now().minusMonths(6));

DateTimeFormatter format = DateTimeFormatter.ofPattern("MMM d yyyy  hh:mm a");

LocalDateTime leaving = LocalDateTime.of(2013, Month.JULY, 20, 19, 30); 

LocalDate date = LocalDate.parse(in, DateTimeFormatter.BASIC_ISO_DATE);

    DateTimeFormatter formatter =
                      DateTimeFormatter.ofPattern("MMM d yyyy");
    LocalDate date = LocalDate.parse(input, formatter); 

Instant t1, t2;
...
long ns = Duration.between(t1, t2).toNanos();

Instant start;
...
Duration gap = Duration.ofSeconds(10);
Instant later = start.plus(gap);

LocalDate today = LocalDate.now();
LocalDate birthday = LocalDate.of(1960, Month.JANUARY, 1);

Period p = Period.between(birthday, today);
long p2 = ChronoUnit.DAYS.between(birthday, today);
System.out.println("You are " + p.getYears() + " years, " + p.getMonths() +
                   " months, and " + p.getDays() +
                   " days old. (" + p2 + " days total)");

The code produces output similar to the following:

You are 53 years, 4 months, and 29 days old. (19508 days total)

Prefix	Method Type	Use
of	static factory	Creates an instance where the factory is primarily validating the input parameters, not converting them.
from	static factory	Converts the input parameters to an instance of the target class, which may involve losing information from the input.
parse	static factory	Parses the input string to produce an instance of the target class.
format	instance	Uses the specified formatter to format the values in the temporal object to produce a string.
get	instance	Returns a part of the state of the target object.
is	instance	Queries the state of the target object.
with	instance	Returns a copy of the target object with one element changed; this is the immutable equivalent to a set method on a JavaBean.
plus	instance	Returns a copy of the target object with an amount of time added.
minus	instance	Returns a copy of the target object with an amount of time subtracted.
to	instance	Converts this object to another type.
at	instance	Combines this object with another.

https://docs.oracle.com/javase/8/docs/api/java/time/format/DateTimeFormatter.html

All letters 'A' to 'Z' and 'a' to 'z' are reserved as pattern letters. The following pattern letters are defined:

  Symbol  Meaning                     Presentation      Examples
  ------  -------                     ------------      -------
   G       era                         text              AD; Anno Domini; A
   u       year                        year              2004; 04
   y       year-of-era                 year              2004; 04
   D       day-of-year                 number            189
   M/L     month-of-year               number/text       7; 07; Jul; July; J
   d       day-of-month                number            10

   Q/q     quarter-of-year             number/text       3; 03; Q3; 3rd quarter
   Y       week-based-year             year              1996; 96
   w       week-of-week-based-year     number            27
   W       week-of-month               number            4
   E       day-of-week                 text              Tue; Tuesday; T
   e/c     localized day-of-week       number/text       2; 02; Tue; Tuesday; T
   F       week-of-month               number            3

   a       am-pm-of-day                text              PM
   h       clock-hour-of-am-pm (1-12)  number            12
   K       hour-of-am-pm (0-11)        number            0
   k       clock-hour-of-am-pm (1-24)  number            0

   H       hour-of-day (0-23)          number            0
   m       minute-of-hour              number            30
   s       second-of-minute            number            55
   S       fraction-of-second          fraction          978
   A       milli-of-day                number            1234
   n       nano-of-second              number            987654321
   N       nano-of-day                 number            1234000000

   V       time-zone ID                zone-id           America/Los_Angeles; Z; -08:30
   z       time-zone name              zone-name         Pacific Standard Time; PST
   O       localized zone-offset       offset-O          GMT+8; GMT+08:00; UTC-08:00;
   X       zone-offset 'Z' for zero    offset-X          Z; -08; -0830; -08:30; -083015; -08:30:15;
   x       zone-offset                 offset-x          +0000; -08; -0830; -08:30; -083015; -08:30:15;
   Z       zone-offset                 offset-Z          +0000; -0800; -08:00;

   p       pad next                    pad modifier      1

   '       escape for text             delimiter
   ''      single quote                literal           '
   [       optional section start
   ]       optional section end
   #       reserved for future use
   {       reserved for future use
   }       reserved for future use