Tutorial Java LocalDate(), LocalDateTime(), ZonedDateTime(), Calendar() și Date()

Publicat: 2020-07-18

Tutorial Java LocalDate(), LocalDateTime(), ZonedDateTime(), Calendar() și Date()

Pe Java, am publicat tutorialele Cum să convertiți ora curentă în ora epocii și Cum să calculați diferența dintre două instanțe de date Java cu ceva timp în urmă.

În acest tutorial vom trece peste toate API-urile Java Date și Calendar de mai jos:

LocalDate():

LocalDate este un obiect imuabil dată-oră care reprezintă o dată, adesea văzută ca an-lună-zi. Pot fi accesate și alte câmpuri de date, cum ar fi ziua anului, ziua săptămânii și săptămâna anului.

LocalDate Java API

LocalDateTime():

LocalDateTime este un obiect data-ora imuabil care reprezintă o dată-oră, adesea văzut ca an-lună-zi-oră-minut-secundă.

LocalDateTime Java API

ZonedDateTime():

ZonedDateTime este o reprezentare imuabilă a unei date-ora cu un fus orar. Această clasă stochează toate câmpurile de dată și oră, cu o precizie de nanosecunde, și un fus orar, cu un offset de zonă utilizat pentru a gestiona date-ora locale ambigue.

ZonedDateTime Java API

Calendar():

Clasa Calendar este o clasă abstractă care oferă metode de conversie între un anumit moment în timp și un set de câmpuri calendaristice, cum ar fi YEAR, MONTH, DAY_OF_MONTH, HOUR și așa mai departe, și pentru manipularea câmpurilor calendaristice, cum ar fi obținerea datei. a saptamanii urmatoare. Un moment în timp poate fi reprezentat printr-o valoare de milisecundă care este o compensare față de Epoca, 1 ianuarie 1970 00:00:00.000 GMT (gregorian).

Data():

Clasa Date reprezintă un anumit moment în timp, cu precizie în milisecunde.

Să începem:

Creați fișier: 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);
    }
 
}

Doar rulați-l în IntelliJ IDEA:

Ieșire de consolă.

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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

Sper că acest tutorial vă va ajuta să utilizați toate aceste API-uri de dată și oră.