Samouczek Java LocalDate(), LocalDateTime(), ZonedDateTime(), Calendar() i Date()

Opublikowany: 2020-07-18

Samouczek Java LocalDate(), LocalDateTime(), ZonedDateTime(), Calendar() i Date()

W języku Java opublikowaliśmy jakiś czas temu samouczki Jak przekonwertować bieżący czas na czas epoki i Jak obliczyć różnicę między dwoma instancjami danych Java.

W tym samouczku omówimy wszystkie poniższe interfejsy API daty i kalendarza Java:

DataLokalna():

LocalDate to niezmienny obiekt daty i godziny, który reprezentuje datę, często postrzeganą jako rok-miesiąc-dzień. Można również uzyskać dostęp do innych pól daty, takich jak dzień roku, dzień tygodnia i tydzień roku.

LocalDate Java API

LocalDateTime():

LocalDateTime to niezmienny obiekt daty i godziny, który reprezentuje datę i godzinę, często postrzeganą jako rok-miesiąc-dzień-godzina-minuta-sekunda.

LocalDateTime Java API

ZonedDateTime():

ZonedDateTime to niezmienna reprezentacja daty i godziny ze strefą czasową. Ta klasa przechowuje wszystkie pola daty i godziny z dokładnością do nanosekund oraz strefę czasową z przesunięciem strefy używanym do obsługi niejednoznacznych lokalnych czasów daty i godziny.

ZonedDateTime Java API

Kalendarz():

Klasa Calendar jest klasą abstrakcyjną, która udostępnia metody konwersji między określoną chwilą w czasie a zestawem pól kalendarza, takich jak ROK, MIESIĄC, DZIEŃ_MIESIĄCA, GODZINA itd., oraz do manipulowania polami kalendarza, na przykład do pobierania daty następnego tygodnia. Chwila w czasie może być reprezentowana przez wartość milisekundową, która jest przesunięciem od Epoki, 1 stycznia 1970 00:00:00.000 GMT (gregoriański).

Data():

Klasa Date reprezentuje określoną chwilę w czasie z dokładnością do milisekund.

Zacznijmy:

Utwórz plik: CrunchifyDateTimeCalendarTutorial.java

CrunchifyDateTimeCalendarTutorial.java
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package crunchify.com.tutorials;
 
import java.text.ParseException;
import java.text.SimpleDateFormat;
import java.time.LocalDate;
import java.time.LocalDateTime;
import java.time.Period;
import java.time.ZonedDateTime;
import java.time.temporal.ChronoUnit;
import java.util.Calendar;
import java.util.Date;
import java.util.GregorianCalendar;
 
/**
* @author Crunchify.com
* version: 1.0
* Tutorial: Java LocalDate(), LocalDateTime(), ZonedDateTime(), Calendar() and Date() Tutorial
*/
 
public class CrunchifyDateTimeCalendarTutorial {
 
    public static void main(String[] args) {
 
        // ************************************************ LocalDate **********************************************
 
        // LocalDate is an immutable date-time object that represents a date, often viewed as year-month-day. Other date fields, such as
        // day-of-year, day-of-week and week-of-year, can also be accessed. For example, the value "2nd October 2007" can be stored in a
        // LocalDate.
 
        crunchifyLog("============ LocalDate test Start ============");
        LocalDate currentLocalDate = LocalDate.now();
        LocalDate currentLocalNewDate = LocalDate.of(2019, 1, 11);
 
        crunchifyLog("LocalDate.now(): " + currentLocalDate);
        crunchifyLog("LocalDate.of(2019, 1, 11): " + currentLocalNewDate);
 
        // Period: A date-based amount of time in the ISO-8601 calendar system, such as '2 years, 3 months and 4 days'.
        Period period = Period.between(currentLocalDate, currentLocalNewDate);
 
        crunchifyLog("Month differences: " + period.getMonths());
        if (period.getMonths() <= -3) {
            crunchifyLog("result: " + currentLocalNewDate + " is older than 3 months!");
        }
 
        LocalDate currentLocalDateNew = LocalDate.now();
        LocalDate threeMonthAgo = LocalDate.now().plusMonths(-3);
 
        crunchifyLog("LocalDate.now(): " + currentLocalDateNew);
        crunchifyLog("LocalDate.now().plusMonths(-3): " + threeMonthAgo);
 
        LocalDate crunchifyLocalDate = LocalDate.of(2019, 1, 11);
 
        // is this date older than 6 months?
        if (crunchifyLocalDate.isBefore(threeMonthAgo)) {
            crunchifyLog("crunchifyLocalDate.isBefore(threeMonthAgo) result: " + crunchifyLocalDate + " is older than 3 months!");
        }
        crunchifyLog("============ LocalDate test End ============ \n");
 
        // ************************************************ LocalDateTime **********************************************
 
        // LocalDateTime is an immutable date-time object that represents a date-time, often viewed as year-month-day-hour-minute-second.
        // Other date and time fields, such as day-of-year, day-of-week and week-of-year, can also be accessed. Time is represented to
        // nanosecond precision. For example, the value "2nd October 2007 at 13:45.30.123456789" can be stored in a LocalDateTime.
 
        crunchifyLog("============ LocalDateTime test Start ============");
 
        LocalDateTime currentDate2 = LocalDateTime.now();
        LocalDateTime fourMonthAgo = LocalDateTime.now().plusMonths(-4);
 
        crunchifyLog("LocalDateTime.now(): " + currentLocalDate);
        crunchifyLog("LocalDateTime.now().plusMonths(-4): " + fourMonthAgo);
 
        LocalDateTime newDate2 = LocalDateTime.of(2019, 7, 1, 0, 0, 0);
 
        // Checks if this date-time is before the specified date-time.
        if (newDate2.isBefore(fourMonthAgo)) {
            crunchifyLog("isBefore() result: " + newDate2 + " is older than 4 months!");
        }
 
        long findGap = ChronoUnit.MONTHS.between(currentDate2, newDate2);
        crunchifyLog(findGap);
        if (findGap <= -4) {
            crunchifyLog("findGap result: " + newDate2 + " is older than 4 months!");
        }
        crunchifyLog("============ LocalDateTime test End ============ \n");
 
        // ************************************************ ZonedDateTime **********************************************
 
        // ZonedDateTime is an immutable representation of a date-time with a time-zone. This class stores all date and time fields, to a
        // precision of nanoseconds, and a time-zone, with a zone offset used to handle ambiguous local date-times. For example, the value
        // "2nd October 2007 at 13:45.30.123456789 +02:00 in the Europe/Paris time-zone" can be stored in a ZonedDateTime.
 
        crunchifyLog("============ ZonedDateTime test Start ============");
 
        ZonedDateTime crunchifyNow = ZonedDateTime.now();
        ZonedDateTime thirtyDaysAgo = crunchifyNow.plusDays(-30);
 
        crunchifyLog("ZonedDateTime.now() :" + crunchifyNow);
        crunchifyLog("now.plusDays(-30) :" + thirtyDaysAgo);
 
        ZonedDateTime fiftyDaysAgo = crunchifyNow.plusDays(-50);
        crunchifyLog("now.plusDays(-50) :" + fiftyDaysAgo);
 
        if (fiftyDaysAgo.isBefore(thirtyDaysAgo)) {
            crunchifyLog("fiftyDaysAgo.isBefore(thirtyDaysAgo): " + thirtyDaysAgo + " is older than 30 days!");
        }
 
        // ChronoUnit: A standard set of date periods units.
        // This set of units provide unit-based access to manipulate a date, time or date-time. The standard set of units can be extended by
        // implementing TemporalUnit.
        long crunchifyBetween = ChronoUnit.DAYS.between(crunchifyNow, fiftyDaysAgo);
        crunchifyLog(crunchifyBetween);
        if (crunchifyBetween < -30) {
            crunchifyLog("crunchifyBetween < -30 result: " + thirtyDaysAgo + " is older than 30 days!");
        }
        crunchifyLog("============ ZonedDateTime test End ============ \n");
 
        // ************************************************ Calendar **********************************************
 
        // The Calendar class is an abstract class that provides methods for converting between a specific instant in time and a set of
        // calendar fields such as YEAR, MONTH, DAY_OF_MONTH, HOUR, and so on, and for manipulating the calendar fields, such as getting the
        // date of the next week. An instant in time can be represented by a millisecond value that is an offset from the Epoch, January 1,
        // 1970 00:00:00.000 GMT (Gregorian).
 
        crunchifyLog("============ Calendar test Start ============");
 
        SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd");
        Calendar fiveMonthsAgo = Calendar.getInstance();
        crunchifyLog("Calendar.getInstance(): " + sdf.format(fiveMonthsAgo.getTime()));
 
        // Adds or subtracts the specified amount of time to the given calendar field, based on the calendar's rules.
        fiveMonthsAgo.add(Calendar.MONTH, -5);
        crunchifyLog("Calendar.MONTH, -5): " + sdf.format(fiveMonthsAgo.getTime()));
 
        Calendar crunchifyCalendar = new GregorianCalendar(2019, 7, 11);
 
        if (crunchifyCalendar.before(threeMonthAgo)) {
            crunchifyLog("crunchifyCalendar.before(threeMonthAgo) result : " + sdf.format(crunchifyCalendar.getTime()) + " is older than 5 months");
        }
        crunchifyLog("============ Calendar test End ============ \n");
 
        // ************************************************ Date **********************************************
 
        // Date: The class Date represents a specific instant in time, with millisecond precision.
        crunchifyLog("============ Date test Start ============");
 
        SimpleDateFormat sdf5 = new SimpleDateFormat("yyyy-MM-dd");
        Date crunchifyToday = new Date();
        crunchifyLog("new Date(): " + sdf5.format(crunchifyToday));
 
        Calendar twentyDaysAgo = Calendar.getInstance();
        twentyDaysAgo.add(Calendar.DAY_OF_MONTH, -20);
 
        Date thirtyDaysAgoDate = twentyDaysAgo.getTime();
        crunchifyLog("twentyDaysAgo.getTime(): " + sdf5.format(thirtyDaysAgoDate));
 
        Date crunchifyNewDate = null;
        try {
            // Parses text from the beginning of the given string to produce a date. The method may not use the entire text of the given string.
            crunchifyNewDate = sdf5.parse("2019-07-11");
        } catch (ParseException e) {
            e.printStackTrace();
        }
 
        if (crunchifyNewDate.before(thirtyDaysAgoDate)) {
            crunchifyLog(sdf.format(crunchifyNewDate) + " is older than 30 days!");
        }
        crunchifyLog("============ Date test End ============ \n");
 
    }
 
    private static void crunchifyLog(Object crunchifyString) {
 
        System.out.println(crunchifyString);
    }
 
}

Po prostu uruchom go w IntelliJ IDEA:

Wyjście konsoli.

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/ Library / Java / JavaVirtualMachines / jdk - 13.0.1.jdk / Contents / Home / bin / java - javaagent : / Applications / IntelliJ IDEA . app / Contents / lib / idea_rt . jar = 50895 : / Applications / IntelliJ IDEA . app / Contents / bin - Dfile . encoding = UTF - 8 - classpath / Users / crunchify / Documents / C / crunchify - github / CrunchifyTutorials / target / classes : / Users / crunchify / Documents / C / crunchify - github / CrunchifyTutorials / WebContent / WEB - INF / lib / zxing - 2.1.jar : / Users / crunchify / Documents / C / crunchify - github / CrunchifyTutorials / WebContent / WEB - INF / lib / commons - logging - 1.1.2.jar : / Users / crunchify / Documents / C / crunchify - github / CrunchifyTutorials / WebContent / WEB - INF / lib / commons - collections - 3.2.1.jar : / Users / crunchify / Documents / C / crunchify - github / CrunchifyTutorials / WebContent / WEB - INF / lib / javax . mail . jar : / Users / crunchify / Documents / C / crunchify - github / CrunchifyTutorials / WebContent / WEB - INF / lib / commons - io - 2.4.jar : / Users / crunchify / Documents / C / crunchify - github / CrunchifyTutorials / WebContent / WEB - INF / lib / commons - lang - 2.6.jar : / Users / crunchify / Documents / C / crunchify - github / CrunchifyTutorials / WebContent / WEB - INF / lib / commons - configuration - 1.9.jar : / Users / crunchify / Documents / C / crunchify - github / CrunchifyTutorials / WebContent / WEB - INF / lib / log4j - 1.2.17.jar : / Users / crunchify / Documents / C / crunchify - github / CrunchifyTutorials / WebContent / WEB - INF / lib / commons - beanutils - 1.8.3.jar : / Users / crunchify / . m2 / repository / org / glassfish / javax . json / 1.0.4 / javax . json - 1.0.4.jar : / Users / crunchify / . m2 / repository / com / github / wnameless / json - flattener / 0.2.2 / json - flattener - 0.2.2.jar : / Users / crunchify / . m2 / repository / com / eclipsesource / minimal - json / minimal - json / 0.9.4 / minimal - json - 0.9.4.jar : / Users / crunchify / . m2 / repository / org / apache / commons / commons - lang3 / 3.4 / commons - lang3 - 3.4.jar : / Users / crunchify / . m2 / repository / com / google / code / gson / gson / 2.8.0 / gson - 2.8.0.jar : / Users / crunchify / . m2 / repository / net / jodah / expiringmap / 0.5.7 / expiringmap - 0.5.7.jar : / Users / crunchify / . m2 / repository / org / apache / httpcomponents / httpclient / 4.3.6 / httpclient - 4.3.6.jar : / Users / crunchify / . m2 / repository / org / apache / httpcomponents / httpcore / 4.3.3 / httpcore - 4.3.3.jar : / Users / crunchify / . m2 / repository / commons - codec / commons - codec / 1.6 / commons - codec - 1.6.jar : / Users / crunchify / . m2 / repository / org / json / json / 20151123 / json - 20151123.jar : / Users / crunchify / . m2 / repository / net / spy / spymemcached / 2.12.3 / spymemcached - 2.12.3.jar : / Users / crunchify / . m2 / repository / com / whalin / Memcached - Java - Client / 3.0.2 / Memcached - Java - Client - 3.0.2.jar : / Users / crunchify / . m2 / repository / commons - pool / commons - pool / 1.5.6 / commons - pool - 1.5.6.jar : / Users / crunchify / . m2 / repository / org / slf4j / slf4j - api / 1.6.4 / slf4j - api - 1.6.4.jar : / Users / crunchify / . m2 / repository / com / googlecode / xmemcached / xmemcached / 2.4.5 / xmemcached - 2.4.5.jar : / Users / crunchify / . m2 / repository / com / paypal / sdk / rest - api - sdk / 1.14.0 / rest - api - sdk - 1.14.0.jar : / Users / crunchify / . m2 / repository / commons - dbcp / commons - dbcp / 20030825.184428 / commons - dbcp - 20030825.184428.jar : / Users / crunchify / . m2 / repository / javax / ws / rs / javax . ws . rs - api / 2.0 / javax . ws . rs - api - 2.0.jar : / Users / crunchify / . m2 / repository / org / hamcrest / hamcrest - all / 1.3 / hamcrest - all - 1.3.jar : / Users / crunchify / . m2 / repository / log4j / log4j / 1.2.17 / log4j - 1.2.17.jar : / Users / crunchify / . m2 / repository / com / google / guava / guava / 19.0 / guava - 19.0.jar : / Users / crunchify / . m2 / repository / com / googlecode / json - simple / json - simple / 1.1 / json - simple - 1.1.jar : / Users / crunchify / . m2 / repository / commons - net / commons - net / 2.0 / commons - net - 2.0.jar : / Users / crunchify / . m2 / repository / asm / asm / 3.3.1 / asm - 3.3.1.jar : / Users / crunchify / . m2 / repository / axis / axis / 1.4 / axis - 1.4.jar : / Users / crunchify / . m2 / repository / org / apache / axis / axis - jaxrpc / 1.4 / axis - jaxrpc - 1.4.jar : / Users / crunchify / . m2 / repository / axis / axis - wsdl4j / 1.5.1 / axis - wsdl4j - 1.5.1.jar : / Users / crunchify / . m2 / repository / commons - beanutils / commons - beanutils / 1.8.3 / commons - beanutils - 1.8.3.jar : / Users / crunchify / . m2 / repository / commons - collections / commons - collections / 3.2.1 / commons - collections - 3.2.1.jar : / Users / crunchify / . m2 / repository / commons - configuration / commons - configuration / 1.10 / commons - configuration - 1.10.jar : / Users / crunchify / . m2 / repository / commons - io / commons - io / 2.4 / commons - io - 2.4.jar : / Users / crunchify / . m2 / repository / commons - discovery / commons - discovery / 0.5 / commons - discovery - 0.5.jar : / Users / crunchify / . m2 / repository / commons - lang / commons - lang / 2.6 / commons - lang - 2.6.jar : / Users / crunchify / . m2 / repository / commons - logging / commons - logging / 1.1.3 / commons - logging - 1.1.3.jar : / Users / crunchify / . m2 / repository / commons - logging / commons - logging - api / 1.1 / commons - logging - api - 1.1.jar : / Users / crunchify / . m2 / repository / javax / mail / mail / 1.4.7 / mail - 1.4.7.jar : / Users / crunchify / . m2 / repository / javax / activation / activation / 1.1 / activation - 1.1.jar : / Users / crunchify / . m2 / repository / javax / xml / jaxrpc - api / 1.1 / jaxrpc - api - 1.1.jar : / Users / crunchify / . m2 / repository / javax / servlet / javax . servlet - api / 3.1.0 / javax . servlet - api - 3.1.0.jar : / Users / crunchify / . m2 / repository / org / apache / axis / axis - saaj / 1.4 / axis - saaj - 1.4.jar : / Users / crunchify / . m2 / repository / wsdl4j / wsdl4j / 1.6.3 / wsdl4j - 1.6.3.jar : / Users / crunchify / . m2 / repository / com / google / zxing / core / 3.2.1 / core - 3.2.1.jar : / Users / crunchify / . m2 / repository / org / apache / commons / commons - compress / 1.9 / commons - compress - 1.9.jar : / Users / crunchify / . m2 / repository / mysql / mysql - connector - java / 5.1.6 / mysql - connector - java - 5.1.6.jar : / Users / crunchify / . m2 / repository / junit / junit / 4.12 / junit - 4.12.jar : / Users / crunchify / . m2 / repository / org / hamcrest / hamcrest - core / 1.3 / hamcrest - core - 1.3.jar : / Users / crunchify / . m2 / repository / ch / qos / logback / logback - classic / 1.2.3 / logback - classic - 1.2.3.jar : / Users / crunchify / . m2 / repository / ch / qos / logback / logback - core / 1.2.3 / logback - core - 1.2.3.jar : / Users / crunchify / . m2 / repository / org / springframework / spring - context / 5.1.3.RELEASE / spring - context - 5.1.3.RELEASE.jar : / Users / crunchify / . m2 / repository / org / springframework / spring - aop / 5.1.3.RELEASE / spring - aop - 5.1.3.RELEASE.jar : / Users / crunchify / . m2 / repository / org / springframework / spring - beans / 5.1.3.RELEASE / spring - beans - 5.1.3.RELEASE.jar : / Users / crunchify / . m2 / repository / org / springframework / spring - core / 5.1.3.RELEASE / spring - core - 5.1.3.RELEASE.jar : / Users / crunchify / . m2 / repository / org / springframework / spring - jcl / 5.1.3.RELEASE / spring - jcl - 5.1.3.RELEASE.jar : / Users / crunchify / . m2 / repository / org / springframework / spring - expression / 5.1.3.RELEASE / spring - expression - 5.1.3.RELEASE.jar : / Users / crunchify / . m2 / repository / org / springframework / spring - context - support / 5.1.3.RELEASE / spring - context - support - 5.1.3.RELEASE.jar crunchify . com . tutorials . CrunchifyDateTimeCalendarTutorial
 
============ LocalDate test Start ============
LocalDate . now ( ) : 2020 - 07 - 18
LocalDate . of ( 2019 , 1 , 11 ) : 2019 - 01 - 11
Month differences : - 6
result : 2019 - 01 - 11 is older than 3 months !
LocalDate . now ( ) : 2020 - 07 - 18
LocalDate . now ( ) . plusMonths ( - 3 ) : 2020 - 04 - 18
crunchifyLocalDate . isBefore ( threeMonthAgo ) result : 2019 - 01 - 11 is older than 3 months !
============ LocalDate test End ============
 
============ LocalDateTime test Start ============
LocalDateTime . now ( ) : 2020 - 07 - 18
LocalDateTime . now ( ) . plusMonths ( - 4 ) : 2020 - 03 - 18T10 : 27 : 28.285711
isBefore ( ) result : 2019 - 07 - 01T00 : 00 is older than 4 months !
- 12
findGap result : 2019 - 07 - 01T00 : 00 is older than 4 months !
============ LocalDateTime test End ============
 
============ ZonedDateTime test Start ============
ZonedDateTime . now ( ) : 2020 - 07 - 18T10 : 27 : 28.286147 - 05 : 00 [ America / Chicago ]
now . plusDays ( - 30 ) : 2020 - 06 - 18T10 : 27 : 28.286147 - 05 : 00 [ America / Chicago ]
now . plusDays ( - 50 ) : 2020 - 05 - 29T10 : 27 : 28.286147 - 05 : 00 [ America / Chicago ]
fiftyDaysAgo . isBefore ( thirtyDaysAgo ) : 2020 - 06 - 18T10 : 27 : 28.286147 - 05 : 00 [ America / Chicago ] is older than 30 days !
- 50
crunchifyBetween < - 30 result : 2020 - 06 - 18T10 : 27 : 28.286147 - 05 : 00 [ America / Chicago ] is older than 30 days !
============ ZonedDateTime test End ============
 
============ Calendar test Start ============
Calendar . getInstance ( ) : 2020 - 07 - 18
Calendar . MONTH , - 5 ) : 2020 - 02 - 18
============ Calendar test End ============
 
============ Date test Start ============
new Date ( ) : 2020 - 07 - 18
twentyDaysAgo . getTime ( ) : 2020 - 06 - 28
2019 - 07 - 11 is older than 30 days !
============ Date test End ============
 
 
Process finished with exit code 0

Mam nadzieję, że ten samouczek pomoże ci wykorzystać wszystkie te interfejsy API daty i godziny.