Java LocalDate(), LocalDateTime(), ZonedDateTime(), Calendar() and Date() บทช่วยสอน

เผยแพร่แล้ว: 2020-07-18

บน Java เราได้เผยแพร่ How to Convert Current Time to Epoch Time และ How to Calculate the Difference between two Java Date Instances tutorials บางครั้งย้อนกลับ

ในบทช่วยสอนนี้ เราจะพูดถึง Java Date และ Calendar API ด้านล่างทั้งหมด:

LocalDate():

LocalDate เป็นอ็อบเจ็กต์วันที่-เวลาที่ไม่เปลี่ยนรูปซึ่งแสดงถึงวันที่ ซึ่งมักถูกมองว่าเป็นวันปีเดือน ฟิลด์วันที่อื่นๆ เช่น วันของปี วันในสัปดาห์ และสัปดาห์ของปี สามารถเข้าถึงได้เช่นกัน

LocalDate Java API

LocalDateTime():

LocalDateTime เป็นออบเจ็กต์วันที่-เวลาที่ไม่เปลี่ยนรูปซึ่งแสดงถึงวันที่-เวลา ซึ่งมักถูกมองว่าเป็นปี-เดือน-วัน-ชั่วโมง-นาที-วินาที

LocalDateTime Java API

ZonedDateTime():

ZonedDateTime คือการแสดงวันที่-เวลากับเขตเวลาที่ไม่เปลี่ยนรูปแบบ คลาสนี้เก็บเขตข้อมูลวันที่และเวลาทั้งหมดเป็นหน่วยนาโนวินาทีและเขตเวลาที่มีความแม่นยำ โดยมีการชดเชยโซนที่ใช้เพื่อจัดการวันที่-เวลาท้องถิ่นที่ไม่ชัดเจน

ZonedDateTime Java API

ปฏิทิน():

คลาสปฏิทินเป็นคลาสนามธรรมที่มีวิธีการแปลงระหว่างช่วงเวลาเฉพาะเจาะจงและชุดของฟิลด์ปฏิทิน เช่น YEAR, MONTH, DAY_OF_MONTH, HOUR และอื่นๆ และสำหรับการจัดการฟิลด์ปฏิทิน เช่น รับวันที่ ของสัปดาห์หน้า ชั่วขณะหนึ่งสามารถแสดงด้วยค่ามิลลิวินาทีที่ชดเชยจากยุค 1 มกราคม 1970 00:00:00.000 GMT (เกรกอเรียน)

วันที่():

คลาส Date แสดงถึงช่วงเวลาที่เฉพาะเจาะจงโดยมีความแม่นยำเป็นมิลลิวินาที

มาเริ่มกันเลย:

สร้างไฟล์: 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);

}

เพียงเรียกใช้ใน IntelliJ IDEA:

เอาต์พุตคอนโซล

/ 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

ฉันหวังว่าบทช่วยสอนนี้จะช่วยให้คุณใช้ Date and Time API เหล่านี้ได้ทั้งหมด