Java 8 – New way to deal with Date and Time

In this article, we will discuss Java 8 Date/Time API. The new Date/Time API was one of the long pending requests from the Java developer community. As the existing Date, related API is not developer friendly. With the older versions of Java, we used third-party date-time libraries like Joda-Time. As part of Java 8, the implementation of  JSR 310 lead by Joda-Time author Stephen Colebourne along with Oracle-provided Date and Time API. This will be available under java package java.time

The main reasons behind the new Date and Time API are,

• Immutability
  • Prior to Java 8, the date classes are mutable. When we are using it as part of multi-threaded environments, developers have to make sure the thread safety of date objects. The Java 8 Date and Time API provides all the immutable classes which are thread safe. Developers are free of concurrency issues.
• Domain Driven Design Approach
  • The classes of new Date and Time API follows “Domain Driven Design”. For developers, understanding of the functionality of methods and classes is very easy.

Now, we will see some of the classes and operations of Date and Time API.

java.time.LocalDate:

The LocalDate provides the only date without time information. It is immutable and thread-safe. Now, we will demonstrate the LocalDate class.

package org.smarttechie;
import java.time.LocalDate;
import java.time.temporal.ChronoUnit;
/**
* This class demonstrates JAVA 8 data and time API
* @author Siva Prasad Rao Janapati
* */
public class DateTimeDemonstration {
/**
* @param args
*/
public static void main(String[] args) {
   //Create date LocalDate localDate = LocalDate.now();
    System.out.println("The local date is :: " + localDate); 

   //Find the length of the month. That is, how many days are there for this month.
   System.out.println("The number of days available for this month:: " + localDate.lengthOfMonth()); 

   //Know the month name
   System.out.println("What is the month name? :: " + localDate.getMonth().name()); 

   //add 2 days to the today's date.
   System.out.println(localDate.plus(2, ChronoUnit.DAYS)); 

   //substract 2 days from today
   System.out.println(localDate.minus(2, ChronoUnit.DAYS)); 

   //Convert the string to date
   System.out.println(localDate.parse("2017-04-07"));
  }
}

java.time.LocalTime:

The LocalTime provides only time without date information. It is immutable and thread-safe. Now, we will demonstrate LocalTime class.

package org.smarttechie;
import java.time.LocalTime;
import java.time.temporal.ChronoUnit;
/**
* This class demonstrates JAVA 8 data and time API
* @author Siva Prasad Rao Janapati
* */
public class DateTimeDemonstration {
/**
* @param args
*/
public static void main(String[] args) {
   //Get local time
   LocalTime localTime = LocalTime.now();
   System.out.println(localTime);
  //Get the hour of the day
  System.out.println("The hour of the day:: " + localTime.getHour());

  //add 2 hours to the time.
  System.out.println(localTime.plus(2, ChronoUnit.HOURS));
  //add 6 minutes to the time.
  System.out.println(localTime.plusMinutes(6));
  //substract 2 hours from current time
  System.out.println(localTime.minus(2, ChronoUnit.HOURS));
 }
}

java.time.LocalDateTime:

The LocalDateTime provides date and time information. It is immutable and thread-safe. Now, we will demonstrate LocalDateTime class.

package orr.smarttechie;

import java.time.LocalDateTime;
import java.time.temporal.ChronoUnit;

/**
* This class demonstrates JAVA 8 data and time API
* @author Siva Prasad Rao Janapati
*
*/
public class DateTimeDemonstration {

/**
* @param args
*/
public static void main(String[] args) {

    //Get LocalDateTime object
    LocalDateTime localDateTime = LocalDateTime.now();

    System.out.println(localDateTime);

    //Find the length of month. That is, how many days are there for this month.
    System.out.println("The number of days available for this month:: " + localDateTime.getMonth().length(true));

    //Know the month name
    System.out.println("What is the month name? :: " + localDateTime.getMonth().name());

    //add 2 days to today's date.
    System.out.println(localDateTime.plus(2, ChronoUnit.DAYS));

    //substract 2 days from today
    System.out.println(localDateTime.minus(2, ChronoUnit.DAYS));

  }
}

java.time.Year:

The Year provides year information. It is immutable and thread-safe. Now, we will demonstrate Year class.

package orr.smarttechie;

import java.time.Year;
import java.time.temporal.ChronoUnit;

/**
* This class demonstrates JAVA 8 data and time API
* @author Siva Prasad Rao Janapati
*
*/
public class DateTimeDemonstration {

/**
* @param args
*/
public static void main(String[] args) {

   //Get year
   Year year = Year.now();
   System.out.println("Year ::" + year);

   //know the year is leap year or not
   System.out.println("Is year[" +year+"] leap year?"+ year.isLeap());
  }
}

java.time.Duration:

The Duration provides quantity or amount of time in terms of seconds and nanoseconds. It is immutable and thread-safe. Now, we will demonstrate Duration class.

package orr.smarttechie;

import java.time.Duration;
import java.time.LocalDateTime;
import java.time.temporal.ChronoUnit;

/**
* This class demonstrates JAVA 8 data and time API
* @author Siva Prasad Rao Janapati
*
*/
public class DateTimeDemonstration {

/**
* @param args
*/
public static void main(String[] args) {

   LocalDateTime localDateTime = LocalDateTime.now();

   //Get the duration between two dates
   Duration duration = Duration.between(localDateTime, localDateTime.plus(2, ChronoUnit.DAYS));
   System.out.println(duration.toDays());
  }
}

java.time.Period:

The Duration provides a quantity or amount of time in terms of years, months and days. It is immutable and thread-safe. Now, we will demonstrate the Period class.

package orr.smarttechie;

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

/**
* This class demonstrates JAVA 8 data and time API
* @author Siva Prasad Rao Janapati
*
*/
public class DateTimeDemonstration {

/**
* @param args
*/
public static void main(String[] args) {

   LocalDate localDate = LocalDate.now();

   Period period = Period.between(localDate, localDate.plus(2, ChronoUnit.DAYS));
   System.out.println(period.getDays());
  }
}

Enjoy the new flavor of Java 8’s Date and Time API !!!

About Siva Prasad Rao Janapati

Siva Janapati is an Architect with experience in building Cloud Native Microservices architectures, Reactive Systems, Large scale distributed systems, and Serverless Systems. Siva has hands-on in architecture, design, and implementation of scalable systems using Cloud, Java, Go lang, Apache Kafka, Apache Solr, Spring, Spring Boot, Lightbend reactive tech stack, APIGEE edge & on-premise and other open-source, proprietary technologies. Expertise working with and building RESTful, GraphQL APIs. He has successfully delivered multiple applications in retail, telco, and financial services domains. He manages the GitHub(https://github.com/2013techsmarts) where he put the source code of his work related to his blog posts.