Java 8 Date and Time API: How to Convert Date to Java 8 Date and Time

In this tutorial, you will learn:

• How to convert Date to Instant
• How to convert Date to LocalDate
• How to convert Date to LocalTime
• How to convert Date to LocalDateTime
• How to convert Date to ZonedDateTime

Example

package com.melody.datetime;

import java.time.Instant;
import java.time.LocalDate;
import java.time.LocalDateTime;
import java.time.LocalTime;
import java.time.ZoneId;
import java.time.ZonedDateTime;
import java.util.Date;

public class ConvertDateToJava8Date {

 public static void main(String[] args) {
  // Date has no timezone
  Date date = new Date();

  // I did not use toString() because it will automatically
  // format the date with the system default timezone
  System.out.println("Date: " + date.toGMTString());

  // Convert Date to Instant.
  // Instant is the equivalent of Date in Java 8 Date API.
  Instant instant = date.toInstant();
  System.out.println("Instant: " + instant);

  ZoneId defaultTimeZone = ZoneId.systemDefault();

  // Convert Instant to LocalDate (using the system default timezone)
  LocalDate localDate = instant.atZone(defaultTimeZone).toLocalDate();
  System.out.println("LocalDate: " + localDate);

  // Convert Instant to LocalTime (using the system default timezone)
  LocalTime localTime = instant.atZone(defaultTimeZone).toLocalTime();
  System.out.println("LocalTime: " + localTime);

  // Convert Instant to LocalDateTime (using the system default timezone)
  LocalDateTime localDateTime = instant.atZone(defaultTimeZone).toLocalDateTime();
  System.out.println("LocalDateTime: " + localDateTime);

  // Convert Instant to ZonedDateTime (using the system default timezone)
  ZonedDateTime zonedDateTime = instant.atZone(defaultTimeZone);
  System.out.println("ZonedDateTime: " + zonedDateTime);
 }
}

Output

Date: 5 Jun 2017 09:01:52 GMT
Instant: 2017-06-05T09:01:52.527Z
LocalDate: 2017-06-05
LocalTime: 17:01:52.527
LocalDateTime: 2017-06-05T17:01:52.527
ZonedDateTime: 2017-06-05T17:01:52.527+08:00[Asia/Shanghai]

Java 8 Date and Time API: How to Compare Date and Time

In this tutorial, you will learn:

• How to compare two given LocalDate (e.g. determine if two LocalDate are equal)
• How to compare two given LocalTime (e.g. determine if two LocalTime are equal)
• How to find the difference between two LocalDate(e.g. number of days in between)
• How to find the difference between two LocalTime (e.g. number of minutes in between)

Example

package com.melody.datetime;

import java.time.LocalDate;
import java.time.LocalTime;
import java.time.temporal.ChronoUnit;

public class CompareDateTimeDemo {

 public static void main(String[] args) {
  // Compare LocalDate and calculate differences between two LocalDate
  LocalDate localDate1 = LocalDate.now();
  LocalDate localDate2 = localDate1.plusDays(30);

  System.out.println("Date 1: " + localDate1);
  System.out.println("Date 2: " + localDate2);
  System.out.println("Date 1 is after Date 2? " + localDate1.isAfter(localDate2));
  System.out.println("Date 1 is before Date 2? " + localDate1.isBefore(localDate2));
  System.out.println("Date 1 is equal to Date 2? " + localDate1.isEqual(localDate2));
  System.out.println("No. of days between Date 1 and Date 2: " + ChronoUnit.DAYS.between(localDate1, localDate2));

  // Compare LocalTime calculate differences between two LocalTime
  LocalTime localTime1 = LocalTime.now();
  LocalTime localTime2 = localTime1.minusHours(3);

  System.out.println("\nTime 1: " + localTime1);
  System.out.println("Time 2: " + localTime2);
  System.out.println("Time 1 is after Time 2? " + localTime1.isAfter(localTime2));
  System.out.println("Time 1 is before Time 2? " + localTime1.isBefore(localTime2));
  System.out.println("No. of hours between Time 1 and Time 2: " + ChronoUnit.HOURS.between(localTime2, localTime1));
 }
}

Output

Date 1: 2017-06-05
Date 2: 2017-07-05
Date 1 is after Date 2? false
Date 1 is before Date 2? true
Date 1 is equal to Date 2? false
No. of days between Date 1 and Date 2: 30

Time 1: 16:53:59.403
Time 2: 13:53:59.403
Time 1 is after Time 2? true
Time 1 is before Time 2? false
No. of hours between Time 1 and Time 2: 3

Java 8 Date and Time API: How to Convert a Time Zone between Countries

In this tutorial, you will learn:

• How to convert a time zone between different countries using the new Java 8 Date and Time API

Example

package com.melody.datetime;

import java.time.LocalDateTime;
import java.time.ZoneId;
import java.time.ZonedDateTime;
import java.time.format.DateTimeFormatter;

public class ConvertTimezoneDemo {

 public static void main(String[] args) {
  DateTimeFormatter formatter = DateTimeFormatter.ofPattern("MM/dd/yyyy hh:mm:ss a");

  String dateAsString = "05/13/2017 07:30:45 AM";

  // Instantiate a LocalDateTime (without timezone)
  LocalDateTime localDateTime = LocalDateTime.parse(dateAsString, formatter);
  System.out.println("Local date & time without timezone: " + localDateTime.format(formatter));

  // Convert LocalDateTime to ZonedDateTime (timezone = Shanghai)
  ZoneId shanghaiZoneId = ZoneId.of("Asia/Shanghai");
  ZonedDateTime shanghaiZonedDateTime = localDateTime.atZone(shanghaiZoneId);
  System.out.println("Date & time in Shanghai: " + shanghaiZonedDateTime.format(formatter)
     + " " + shanghaiZonedDateTime.getZone());

  // Convert ZonedDateTime to another timezone
  ZoneId newYorkZoneId = ZoneId.of("America/New_York");
  ZonedDateTime newYorkZonedDateTime = shanghaiZonedDateTime.withZoneSameInstant(newYorkZoneId);
  System.out.println("Date & time in New York: " + newYorkZonedDateTime.format(formatter)
    + " " + newYorkZonedDateTime.getZone());
 }
}

Output

Local date & time without timezone: 05/13/2017 07:30:45 AM
Date & time in Shanghai: 05/13/2017 07:30:45 AM Asia/Shanghai
Date & time in New York: 05/12/2017 07:30:45 PM America/New_York