LocalDate today = LocalDate.now(); System.out.println("Today's Local date : " + today); Output Today's Local date : 2020-01-14
LocalDate today = LocalDate.now(); int year = today.getYear(); int month = today.getMonthValue(); int day = today.getDayOfMonth(); System.out.printf("Year : %d Month : %d day : %d /t %n", year, month, day); Output Today's Local date : 2020-01-14 Year : 2020 Month : 1 day : 14
LocalDate dateOfBirth = LocalDate.of(2010, 01, 14); System.out.println("Your Date of birth is : " + dateOfBirth); Output : Your Date of birth is : 2010-01-14
LocalDate date1 = LocalDate.of(2020, 01, 14); if(date1.equals(today)){ System.out.printf("Today %s and date1 %s are same date %n", today, date1); } Output today 2020-01-14 and date1 2020-01-14 are same date
LocalDate dateOfBirth = LocalDate.of(2010, 01, 14); MonthDay birthday = MonthDay.of(dateOfBirth.getMonth(), dateOfBirth.getDayOfMonth()); MonthDay currentMonthDay = MonthDay.from(today); if(currentMonthDay.equals(birthday)){ System.out.println("Many Many happy returns of the day !!"); }else{ System.out.println("Sorry, today is not your birthday"); } Output: Many Many happy returns of the day !!
LocalTime time = LocalTime.now(); System.out.println("local time now : " + time); Output local time now : 16:33:33.369 // in hour, minutes, seconds, nano seconds
LocalTime time = LocalTime.now(); LocalTime newTime = time.plusHours(2); // adding two hours System.out.println("Time after 2 hours : " + newTime); Output : Time after 2 hours : 18:33:33.369
LocalDate nextWeek = today.plus(1, ChronoUnit.WEEKS); System.out.println("Today is : " + today); System.out.println("Date after 1 week : " + nextWeek); Output: Today is : 2020-01-14 Date after 1 week : 2020-01-21
LocalDate previousYear = today.minus(1, ChronoUnit.YEARS); System.out.println("Date before 1 year : " + previousYear); LocalDate nextYear = today.plus(1, YEARS); System.out.println("Date after 1 year : " + nextYear); Output: Date before 1 year : 2019-01-14 Date after 1 year : 2021-01-14
// Returns the current time based on your system clock and set to UTC. Clock clock = Clock.systemUTC(); System.out.println("Clock : " + clock); // Returns time based on system clock zone Clock defaultClock = Clock.systemDefaultZone(); System.out.println("Clock : " + clock); Output: Clock : SystemClock[Z] Clock : SystemClock[Z]
public class MyClass { private Clock clock; // dependency inject ... public void process(LocalDate eventDate) { if(eventDate.isBefore(LocalDate.now(clock)) { ... } } }
LocalDate tomorrow = LocalDate.of(2020, 1, 15); if(tommorow.isAfter(today)){ System.out.println("Tomorrow comes after today"); } LocalDate yesterday = today.minus(1, DAYS); if(yesterday.isBefore(today)){ System.out.println("Yesterday is day before today"); } Output: Tomorrow comes after today Yesterday is day before today
// Date and time with timezone in Java 8 ZoneId america = ZoneId.of("America/New_York"); LocalDateTime localtDateAndTime = LocalDateTime.now(); ZonedDateTime dateAndTimeInNewYork = ZonedDateTime.of(localtDateAndTime, america ); System.out.println("Current date and time in a particular timezone : " + dateAndTimeInNewYork); Output : Current date and time in a particular timezone : 2020-01-14T16:33:33.373-05:00[America/New_York]
Exception in thread "main" java.time.zone.ZoneRulesException: Unknown time-zone ID: ASIA/Tokyo at java.time.zone.ZoneRulesProvider.getProvider(ZoneRulesProvider.java:272) at java.time.zone.ZoneRulesProvider.getRules(ZoneRulesProvider.java:227) at java.time.ZoneRegion.ofId(ZoneRegion.java:120) at java.time.ZoneId.of(ZoneId.java:403) at java.time.ZoneId.of(ZoneId.java:351)
YearMonth currentYearMonth = YearMonth.now(); System.out.printf("Days in month year %s: %d%n", currentYearMonth, currentYearMonth.lengthOfMonth()); YearMonth creditCardExpiry = YearMonth.of(2018, Month.FEBRUARY); System.out.printf("Your credit card expires on %s %n", creditCardExpiry); Output: Days in month year 2020-01: 31 Your credit card expires on 2018-02
if(today.isLeapYear()){ System.out.println("This year is Leap year"); }else { System.out.println("2020 is not a Leap year"); } Output: 2020 is not a Leap year
LocalDate java8Release = LocalDate.of(2020, Month.MARCH, 14); Period periodToNextJavaRelease = Period.between(today, java8Release); System.out.println("Months left between today and Java 8 release : " + periodToNextJavaRelease.getMonths() ); Output: Months left between today and Java 8 release : 2
LocalDateTime datetime = LocalDateTime.of(2020, Month.JANUARY, 14, 19, 30); ZoneOffset offset = ZoneOffset.of("+05:30"); OffsetDateTime date = OffsetDateTime.of(datetime, offset); System.out.println("Date and Time with timezone offset in Java : " + date); Output : Date and Time with timezone offset in Java : 2020-01-14T19:30+05:30
Instant timestamp = Instant.now(); System.out.println("What is value of this instant " + timestamp); Output : What is value of this instant 2020-01-14T08:33:33.379Z
String dayAfterTommorrow = "20200116"; LocalDate formatted = LocalDate.parse(dayAfterTommorrow, DateTimeFormatter.BASIC_ISO_DATE); System.out.printf("Date generated from String %s is %s %n", dayAfterTommorrow, formatted); Output : Date generated from String 20200116 is 2020-01-16
String goodFriday = "Apr 18 2020"; try { DateTimeFormatter formatter = DateTimeFormatter.ofPattern("MMM dd yyyy"); LocalDate holiday = LocalDate.parse(goodFriday, formatter); System.out.printf("Successfully parsed String %s, date is %s%n", goodFriday, holiday); } catch (DateTimeParseException ex) { System.out.printf("%s is not parsable!%n", goodFriday); ex.printStackTrace(); } Output : Successfully parsed String Apr 18 2020, date is 2020-04-18
LocalDateTime arrivalDate = LocalDateTime.now(); try { DateTimeFormatter format = DateTimeFormatter.ofPattern("MMM dd yyyy hh:mm a"); String landing = arrivalDate.format(format); System.out.printf("Arriving at : %s %n", landing); } catch (DateTimeException ex) { System.out.printf("%s can't be formatted!%n", arrivalDate); ex.printStackTrace(); } Output : Arriving at : Jan 14 2020 04:33 PM
Instant ins= Instant.now(); System.out.println("10位 秒"+ins.getEpochSecond()); System.out.println("13位 毫秒"+ins.toEpochMilli());
每个 Java 开发人员都应该至少了解这套新的 API 中的这五个类:
原文: https://rumenz.com/rumenbiji/java8-java-time.html