What is the use of the toEpochSecond() method in Java 9?

In this article, we will learn about the use of the toEpochSecond() method in Java 9. First, we will learn about the LocalDate class, its methods, then we will know about the Epoch Time and the toEpochSecond() method with its uses and example in Java.

LocalDate Class

The LocalDate class is a part of java.time package. LocalDate class represents a date without a time-zone in the ISO-8601 calendar system, such as 2020-10-14. This class represents a date in the format yyyy-MM-dd.

The following are some of the common methods of the LocalDate Class

• getDayOfMonth(): This method gives the day-of-month field.
  
• getDayOfWeek(): This method gives the day-of-week field, which is an enum DayOfWeek.
  
• getDayOfYear(): This method gives the day-of-year field.

What is Epoch Time?

The epoch time (or Unix time, or POSIX time) is a timekeeping system. It counts the number of seconds that have passed since 00:00:00 UTC on January 1, 1970, which is the start of the Unix epoch. This is commonly used in computing systems for timestamps.

Java toEpochSecond() Method

In Java 9, the LocalDate class provides the toEpochSecond() method to convert a local date into epoch seconds. The toEpochSecond() method converts the LocalDate to a number of seconds since the epoch 1970-01-01T00:00:00Z. The LocalDate can be combined with a given time and zone offset to calculate seconds starting from 1970-01-01T00:00:00Z.

Syntax

The following is the syntax of the toEpochSecond() method declaration:

public long toEpochSecond(LocalDate date, ZoneOffset offset)

Parameters:

• date: The date that is to be used for epoch second calculation as the target date.
  
• offset: The zone offset used for the conversion.
  

Uses of the toEpochSecond() Method

The following are some use cases of the toEpochSecond() method in Java 9:

• Timestamp Storage: The toEpochSecond() method is useful in storing timestamps in databases or files, and also helps in comparing temporal values numerically.
• Date Arithmetic: Using the toEpochSecond() method it is easier to perform calculations with simple numeric values.
• Work with different systems: Many systems and APIs use epoch time as their standard time representation, and use it to compare dates across different programming languages.

Example of toEpochSecond() Method

Below is an example of the toEpochSecond() method to print the local date in Epoch time in Java:

import java.time.LocalDate;
import java.time.LocalTime;
import java.time.ZoneOffset;

public class ToEpochSecondMethodTest {
   public static void main(String args[]) {
      LocalDate date = LocalDate.now();
      LocalTime time = LocalTime.now();

      System.out.println("LocalDate toEpochSecond : " + date.toEpochSecond(time, ZoneOffset.of("Z")));
      System.out.println("LocalTime toEpochSecond : " + time.toEpochSecond(date, ZoneOffset.of("Z")));
   }
}

Output

LocalDate toEpochSecond : 1583496984
LocalTime toEpochSecond : 1583496984