Java 8 – How to convert LocalTime to java.util.Date and vice-versa ?

August 24, 2022 SJ Java 8, Java 8 Date/Time 0

In this article, we will learn how to convert LocalTime to java.util.Date using different methods provided in Java 1.8 version and vice-versa

Date class in Java 1.8 version :

  • There are 2 new methods introduced in Java 1.8 version for Date class, those are
    1. from(Instant) – This static method obtains an instance of Date from an Instant object
    2. toInstant() – This method converts invoking Date object to an Instant
  • Note: Many legacy methods of Date class are deprecated

1. Convert LocalTime to java.util.Date :

  • LocalTime consist of only Time information whereas java.util.Date requires Date, Time and Zone information
    • java.util.Date = Date + LocalTime + Zone information
    • For LocalTime to java.util.Date conversion, Time-Zone and Date informations is required
  • Date.from() method accepts Instant as input–argument
    1. Convert LocalTime to LocalDateTime using atDate() method passing LocalDate as argument
    2. And then convert LocalDateTime to ZonedDateTime using atZone() method passing ZoneId as argument and then invoke toInstant() method which returns an Instant
    3. Now, pass above converted Instant to Date.from() method which will return java.util.Date
  • Converted java.util.Date will have,
    1. Date part added as today’s date
    2. Adding System default Zone information
    3. Time part same as that of LocalTime
  • In short, LocalTime -> LocalDateTime -> ZonedDateTime -> Instant -> java.util.Date
  • Lets see an example for conversion of LocalTime to java.util.Date in the below illustration

ConvertLocalTimeToJavaUtilDate.java

package in.bench.resources.java8.date.examples;

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

public class ConvertLocalTimeToJavaUtilDate {

	public static void main(String[] args) {

		// 1. get current system time
		LocalTime localTime = LocalTime.now();
		System.out.println("Current system time is :- \n" 
				+ localTime);


		// 2. get current system date
		LocalDate localDate = LocalDate.now();
		System.out.println("\nCurrent system date is :- \n" 
				+ localDate);


		// 3. get default time zone
		ZoneId zoneId = ZoneId.systemDefault();
		System.out.println("\nDefault time-zone is :- \n" 
				+ zoneId);


		// 4. convert LocalTime -> LocalDateTime -> ZonedDateTime -> Instant
		Instant instant = localTime // LocalTime
				.atDate(localDate) // LocalDateTime
				.atZone(zoneId) // ZonedDateTime
				.toInstant(); // Instant
		System.out.println("\nCurrent Instant at UTC/GMT is :- \n" 
				+ instant);


		// 5. finally convert to Date
		Date date = Date.from(instant);
		System.out.print("\nConverted date is :- \n" + date);
	}
}

Output:

Current system time is :- 
20:20:59.403629200

Current system date is :- 
2022-08-23

Default time-zone is :- 
Asia/Calcutta

Current Instant at UTC/GMT is :- 
2022-08-23T14:50:59.403629200Z

Converted date is :- 
Tue Aug 23 20:20:59 IST 2022

2. Convert java.util.Date to LocalTime :

  • Get java.util.Date instantiating Date object for conversion to LocalTime
  • Conversion steps –
    1. Convert Date to Instant using toInstant() method which returns an Instant
    2. And then invoke ofInstant() method passing converted Instant & ZoneId as arguments which returns LocalDateTime
    3. And then invoke toLocalTime() method which returns LocalTime
  • In short, java.util.Date -> Instant -> LocalDateTime -> LocalTime
  • Read Java 8 – How to convert java.util.Date to LocalTime in different ways ?
  • Lets see an example for conversion of java.util.Date to LocalTime in the below illustration

ConvertJavaUtilDateToLocalTime.java

package in.bench.resources.java8.date.examples;

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

public class ConvertJavaUtilDateToLocalTime {

	public static void main(String[] args) {

		// 1. get current date/time using java.util.Date
		Date date = new Date();
		System.out.println("Current Date/time is :- \n" 
				+ date);


		// 2. get default time zone
		ZoneId zoneId = ZoneId.systemDefault();
		System.out.println("\nDefault time-zone is :- \n" 
				+ zoneId);


		// 3. First, convert Date to Instant
		Instant instant = date.toInstant();
		System.out.println("\nInstant is :- \n" 
				+ instant);


		// 4. Second, Instant -> LocalDateTime
		LocalDateTime localDateTime = LocalDateTime
				.ofInstant(instant, zoneId);
		System.out.println("\nLocalDateTime is :- \n" 
				+ localDateTime);


		// 5. Finally convert, Date -> Instant -> LocalDateTime -> LocalTime
		LocalTime localTime = localDateTime.toLocalTime();
		System.out.print("\nLocalTime is :- \n" + localTime);
	}
}

Output:

Current Date/time is :- 
Tue Aug 23 20:23:17 IST 2022

Default time-zone is :- 
Asia/Calcutta

Instant is :- 
2022-08-23T14:53:17.928Z

LocalDateTime is :- 
2022-08-23T20:23:17.928

LocalTime is :- 
20:23:17.928

Related Articles:

References:

Happy Coding !!
Happy Learning !!

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