Java Language Dates and Time (java.time.*) Usage of various classes of Date Time API
Example
Following example also have explanation required for understanding example within it.
import java.time.Clock;
import java.time.Duration;
import java.time.Instant;
import java.time.LocalDate;
import java.time.LocalDateTime;
import java.time.LocalTime;
import java.time.ZoneId;
import java.time.ZonedDateTime;
import java.util.TimeZone;
public class SomeMethodsExamples {
/**
* Has the methods of the class {@link LocalDateTime}
*/
public static void checkLocalDateTime() {
LocalDateTime localDateTime = LocalDateTime.now();
System.out.println("Local Date time using static now() method ::: >>> "
+ localDateTime);
LocalDateTime ldt1 = LocalDateTime.now(ZoneId.of(ZoneId.SHORT_IDS
.get("AET")));
System.out
.println("LOCAL TIME USING now(ZoneId zoneId) method ::: >>>>"
+ ldt1);
LocalDateTime ldt2 = LocalDateTime.now(Clock.system(ZoneId
.of(ZoneId.SHORT_IDS.get("PST"))));
System.out
.println("Local TIME USING now(Clock.system(ZoneId.of())) ::: >>>> "
+ ldt2);
System.out
.println("Following is a static map in ZoneId class which has mapping of short timezone names to their Actual timezone names");
System.out.println(ZoneId.SHORT_IDS);
}
/**
* This has the methods of the class {@link LocalDate}
*/
public static void checkLocalDate() {
LocalDate localDate = LocalDate.now();
System.out.println("Gives date without Time using now() method. >> "
+ localDate);
LocalDate localDate2 = LocalDate.now(ZoneId.of(ZoneId.SHORT_IDS
.get("ECT")));
System.out
.println("now() is overridden to take ZoneID as parametere using this we can get the same date under different timezones. >> "
+ localDate2);
}
/**
* This has the methods of abstract class {@link Clock}. Clock can be used
* for time which has time with {@link TimeZone}.
*/
public static void checkClock() {
Clock clock = Clock.systemUTC();
// Represents time according to ISO 8601
System.out.println("Time using Clock class : " + clock.instant());
}
/**
* This has the {@link Instant} class methods.
*/
public static void checkInstant() {
Instant instant = Instant.now();
System.out.println("Instant using now() method :: " + instant);
Instant ins1 = Instant.now(Clock.systemUTC());
System.out.println("Instants using now(Clock clock) :: " + ins1);
}
/**
* This class checks the methods of the {@link Duration} class.
*/
public static void checkDuration() {
// toString() converts the duration to PTnHnMnS format according to ISO
// 8601 standard. If a field is zero its ignored.
// P is the duration designator (historically called "period") placed at
// the start of the duration representation.
// Y is the year designator that follows the value for the number of
// years.
// M is the month designator that follows the value for the number of
// months.
// W is the week designator that follows the value for the number of
// weeks.
// D is the day designator that follows the value for the number of
// days.
// T is the time designator that precedes the time components of the
// representation.
// H is the hour designator that follows the value for the number of
// hours.
// M is the minute designator that follows the value for the number of
// minutes.
// S is the second designator that follows the value for the number of
// seconds.
System.out.println(Duration.ofDays(2));
}
/**
* Shows Local time without date. It doesn't store or represenet a date and
* time. Instead its a representation of Time like clock on the wall.
*/
public static void checkLocalTime() {
LocalTime localTime = LocalTime.now();
System.out.println("LocalTime :: " + localTime);
}
/**
* A date time with Time zone details in ISO-8601 standards.
*/
public static void checkZonedDateTime() {
ZonedDateTime zonedDateTime = ZonedDateTime.now(ZoneId
.of(ZoneId.SHORT_IDS.get("CST")));
System.out.println(zonedDateTime);
}
}
