Java8中时间日期库的20个常用使用示例
发布时间:2020-12-15 03:13:22 所属栏目:Java 来源:网络整理
导读:今天PHP站长网 52php.cn把收集自互联网的代码分享给大家,仅供参考。 Instant——它代表的是时间戳 LocalDate——不包含具体时间的日期,比如2014-01-14。它可以用来存储生日,周年纪念日,入职日期等。 LocalTime——它
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Java 8是如何处理时间及日期的示例1 如何 在Java 8中获取当天的日期LocalDate today = LocalDate.now(); System.out.println("Today's Local date : " + today); Output Today's Local date : 2014-01-14 示例2 如何在Java 8中获取当前的年月日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 : 2014-01-14 Year : 2014 Month : 1 day : 14 示例3 在Java 8中如何获取某个特定的日期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 示例4 在Java 8中如何检查两个日期是否相等LocalDate date1 = LocalDate.of(2014,14); if(date1.equals(today)){ System.out.printf("Today %s and date1 %s are same date %n",today,date1); } Output today 2014-01-14 and date1 2014-01-14 are same date 示例5 在Java 8中如何检查重复事件,比如说生日LocalDate dateOfBirth = LocalDate.of(2010,14); 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 !! 示例6 如何在Java 8中获取当前时间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 示例7 如何增加时间里面的小时数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 示例8 如何获取1周后的日期LocalDate nextWeek = today.plus(1,ChronoUnit.WEEKS); System.out.println("Today is : " + today); System.out.println("Date after 1 week : " + nextWeek); Output: Today is : 2014-01-14 Date after 1 week : 2014-01-21 示例9 一年前后的日期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 : 2013-01-14 Date after 1 year : 2015-01-14 示例10 在Java 8中使用时钟// 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)) { ... } } } 示例11 在Java中如何判断某个日期是在另一个日期的前面还是后面LocalDate tomorrow = LocalDate.of(2014,1,15); 、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 示例12 在Java 8中处理不同的时区// 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 : 2014-01-14T16:33:33.373-05:00[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) 示例13 如何表示固定的日期,比如信用卡过期时间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 2014-01: 31 Your credit card expires on 2018-02 示例14 如何在Java 8中检查闰年if(today.isLeapYear()){ System.out.println("This year is Leap year"); }else { System.out.println("2014 is not a Leap year"); } Output: 2014 is not a Leap year 示例15 两个日期之间包含多少天,多少个月LocalDate java8Release = LocalDate.of(2014,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 示例16 带时区偏移量的日期与时间LocalDateTime datetime = LocalDateTime.of(2014,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 : 2014-01-14T19:30+05:30 示例17 在Java 8中如何获取当前时间戳Instant timestamp = Instant.now(); System.out.println("What is value of this instant " + timestamp); Output : What is value of this instant 2014-01-14T08:33:33.379Z 示例18 如何在Java 8中使用预定义的格式器来对日期进行解析/格式化String dayAfterTommorrow = "20140116"; 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 20140116 is 2014-01-16 示例19 如何在Java中使用自定义的格式器来解析日期String goodFriday = "Apr 18 2014"; 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 2014,date is 2014-04-18 示例20 如何在Java 8中对日期进行格式化,转换成字符串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 2014 04:33 PM Java 8中日期与时间API的几个关键点
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