Dates and Times

The java.time package

Java 8 added an easy set of date and time classes in java.time:

import java.time.LocalDate;

public class Main {
    public static void main(String[] args) {
        LocalDate d = LocalDate.of(2026, 8, 15);
        System.out.println(d);
        System.out.println(d.getDayOfWeek());
        System.out.println(d.plusDays(20));
        System.out.println(d.minusMonths(1));
        System.out.println(d.isLeapYear());
    }
}

Output

2026-08-15
SATURDAY
2026-09-04
2026-07-15
false

LocalDate.now() gives today's date. Dates can't be changed: plusDays gives you a new date, just like String methods do.

How many days between two dates?

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

public class Main {
    public static void main(String[] args) {
        LocalDate today = LocalDate.of(2026, 10, 18);
        LocalDate newYear = LocalDate.of(2027, 1, 1);
        System.out.println(ChronoUnit.DAYS.between(today, newYear) + " days to go");
    }
}

Output

75 days to go

Formatting and reading dates

import java.time.LocalDate;
import java.time.LocalTime;
import java.time.format.DateTimeFormatter;

public class Main {
    public static void main(String[] args) {
        DateTimeFormatter fmt = DateTimeFormatter.ofPattern("dd/MM/yyyy");
        LocalDate birthday = LocalDate.parse("25/12/2000", fmt);
        System.out.println(birthday);
        System.out.println(birthday.format(DateTimeFormatter.ofPattern("d MMMM yyyy")));

        LocalTime t = LocalTime.of(9, 45).plusMinutes(30);
        System.out.println(t);
    }
}

Output

2000-12-25
25 December 2000
10:15

Tip: In patterns, MM is the month and mm is minutes. Mixing them up is a classic bug.