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rootulp's solution

to Gigasecond in the Java Track

Published at Jul 13 2018 · 1 comment
Test suite


This solution was written on an old version of Exercism. The tests below might not correspond to the solution code, and the exercise may have changed since this code was written.

Calculate the moment when someone has lived for 10^9 seconds.

A gigasecond is 10^9 (1,000,000,000) seconds.

Running the tests

You can run all the tests for an exercise by entering

$ gradle test

in your terminal.


Chapter 9 in Chris Pine's online Learn to Program tutorial. http://pine.fm/LearnToProgram/?Chapter=09

Submitting Incomplete Solutions

It's possible to submit an incomplete solution so you can see how others have completed the exercise.


import org.junit.Test;
import org.junit.Ignore;

import java.time.LocalDate;
import java.time.LocalDateTime;
import java.time.Month;

import static org.junit.Assert.assertEquals;

public class GigasecondTest {

    public void modernTime() {
        Gigasecond gigaSecond = new Gigasecond(LocalDate.of(2011, Month.APRIL, 25));

        assertEquals(LocalDateTime.of(2043, Month.JANUARY, 1, 1, 46, 40), gigaSecond.getDate());

    @Ignore("Remove to run test")
    public void afterEpochTime() {
        Gigasecond gigaSecond = new Gigasecond(LocalDate.of(1977, Month.JUNE, 13));

        assertEquals(LocalDateTime.of(2009, Month.FEBRUARY, 19, 1, 46, 40), gigaSecond.getDate());

    @Ignore("Remove to run test")
    public void beforeEpochTime() {
        Gigasecond gigaSecond = new Gigasecond(LocalDate.of(1959, Month.JULY, 19));

        assertEquals(LocalDateTime.of(1991, Month.MARCH, 27, 1, 46, 40), gigaSecond.getDate());

    @Ignore("Remove to run test")
    public void withFullTimeSpecified() {
        Gigasecond gigaSecond = new Gigasecond(LocalDateTime.of(2015, Month.JANUARY, 24, 22, 0, 0));

        assertEquals(LocalDateTime.of(2046, Month.OCTOBER, 2, 23, 46, 40), gigaSecond.getDate());

    @Ignore("Remove to run test")
    public void withFullTimeSpecifiedAndDayRollover() {
        Gigasecond gigaSecond = new Gigasecond(LocalDateTime.of(2015, Month.JANUARY, 24, 23, 59, 59));

        assertEquals(LocalDateTime.of(2046, Month.OCTOBER, 3, 1, 46, 39), gigaSecond.getDate());
import java.time.LocalDate;
import java.time.LocalDateTime;

public class Gigasecond {

  private LocalDateTime now;
  private static long GIGASECONDS = 1000000000L;

  public Gigasecond(LocalDate localDate) {
    this.now = localDate.atStartOfDay();

  public Gigasecond(LocalDateTime localDateTime) {
    this.now = localDateTime;

  public LocalDateTime getDate() {
    return now.plusSeconds(GIGASECONDS);


Community comments

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Avatar of ChristianWilkie

I think the name "now" is sorta confusing since it isn't actually the present date/time but rather the date/time of the person's gigasecond birthday.

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