Java LocalDate(), LocalDateTime(), ZonedDateTime(), Calendar() 및 Date() 자습서

게시 됨: 2020-07-18

Java LocalDate(), LocalDateTime(), ZonedDateTime(), Calendar() 및 Date() 자습서

Java에서 우리는 현재 시간을 Epoch 시간으로 변환하는 방법과 두 Java 날짜 인스턴스 간의 차이를 계산하는 방법 자습서를 언젠가 게시했습니다.

이 자습서에서는 아래의 모든 Java 날짜 및 달력 API를 살펴보겠습니다.

지역 날짜():

LocalDate는 날짜를 나타내는 변경할 수 없는 날짜-시간 개체로, 종종 년-월-일로 표시됩니다. 요일, 요일 및 요일과 같은 다른 날짜 필드에도 액세스할 수 있습니다.

LocalDate 자바 API

LocalDateTime():

LocalDateTime은 날짜-시간을 나타내는 변경할 수 없는 날짜-시간 개체로, 종종 년-월-일-시-분-초로 표시됩니다.

LocalDateTime 자바 API

존 날짜 시간():

ZonedDateTime은 표준 시간대가 있는 날짜-시간의 변경할 수 없는 표현입니다. 이 클래스는 모든 날짜 및 시간 필드를 나노초의 정밀도로 저장하고 시간대 오프셋을 사용하여 모호한 로컬 날짜-시간을 처리하는 데 사용합니다.

ZonedDateTime 자바 API

달력():

Calendar 클래스는 YEAR, MONTH, DAY_OF_MONTH, HOUR 등과 같은 달력 필드 집합과 특정 순간 간의 변환 및 날짜 가져오기와 같은 달력 필드 조작을 위한 메서드를 제공하는 추상 클래스입니다. 다음 주. 시간의 순간은 Epoch, 1970년 1월 1일 00:00:00.000 GMT(그레고리안)에서 오프셋인 밀리초 값으로 나타낼 수 있습니다.

날짜():

Date 클래스는 밀리초 정밀도로 특정 순간을 나타냅니다.

시작하자:

파일 생성: 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);
    }
 
}

IntelliJ IDEA에서 실행하기만 하면 됩니다.

콘솔 출력.

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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 - 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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

이 튜토리얼이 이러한 모든 날짜 및 시간 API를 활용하는 데 도움이 되기를 바랍니다.