The java.time.DayOfWeek enums in Java 8 Date-Time API describes the days of the week. The enum has constants value from DayOfWeek.MONDAY through DayOfWeek.SUNDAY. These enums also have their integer values where 1 is equal to MONDAY and 7 is equal to SUNDAY.

In the code snippet below you can see a couple usage of the DayOfWeek enums. We start by getting all the enum values using the values() method that return an array of DayOfWeek. We iterate this array and print out the enum value and its corresponding integer value.

// Get DayOfWeek enums value
DayOfWeek[] dayOfWeeks = DayOfWeek.values();
for (int i = 0; i < dayOfWeeks.length; i++) {
    DayOfWeek dayOfWeek = dayOfWeeks[i];
    System.out.println("dayOfWeek[" + i + "] = " + dayOfWeek + "; value = " +
            dayOfWeek.getValue());
}

To create a DayOfWeek object we can use the of(int) factory method. We pass an integer value of this method. For example giving 1 will give us the DayOfWeek.MONDAY. We can also utilize enum valueOf(String) method to create enum from string value.

// Get DayOfWeek from int value
DayOfWeek dayOfWeek = DayOfWeek.of(1);
System.out.println("dayOfWeek = " + dayOfWeek);

// Get DayOfWeek from string value
dayOfWeek = DayOfWeek.valueOf("SATURDAY");
System.out.println("dayOfWeek = " + dayOfWeek);

To get the DayOfWeek from a date-time object we can use the getDayOfWeek() method. Below we get the day of week from a LocalDate object.

// Get DayOfWeek of a date object
LocalDate date = LocalDate.now();
DayOfWeek dow = date.getDayOfWeek();

System.out.println("Date  = " + date);
System.out.println("Dow   = " + dow + "; value = " + dow.getValue());

We can also get the day of week for a specific locale. To do this we can use the DayOfWeek.getDisplayName(TextStyle, Locale) method. The TextStyle can be of value TextStyle.FULL, TextStyle.SHORT, TextStyle.NARROW which will give us the full, short, and narrow version of the display name. The example below get the display name for Indonesian and German version.

// Get DayOfWeek display name in different locale.
Locale locale = new Locale("id", "ID");
String indonesian = dow.getDisplayName(TextStyle.SHORT, locale);
System.out.println("ID = " + indonesian);

String germany = dow.getDisplayName(TextStyle.FULL, Locale.GERMANY);
System.out.println("DE = " + germany);

There is also a plus(long) method that can be used to add number of days to a DayOfWeek object. For example adding 4 to MONDAY will give us DayOfWeek.FRIDAY.

// Adding number of days to DayOfWeek enum.
System.out.println("DayOfWeek.MONDAY.plus(4) = " + DayOfWeek.MONDAY.plus(4));

Here is the complete code for the snippets above:

package org.kodejava.datetime;

import java.time.DayOfWeek;
import java.time.LocalDate;
import java.time.format.TextStyle;
import java.util.Locale;

public class DayOffWeekExample {
    public static void main(String[] args) {
        // Get DayOfWeek enums value
        DayOfWeek[] dayOfWeeks = DayOfWeek.values();
        for (int i = 0; i < dayOfWeeks.length; i++) {
            DayOfWeek dayOfWeek = dayOfWeeks[i];
            System.out.println("dayOfWeek[" + i + "] = " + dayOfWeek + "; value = " +
                    dayOfWeek.getValue());
        }

        // Get DayOfWeek from int value
        DayOfWeek dayOfWeek = DayOfWeek.of(1);
        System.out.println("dayOfWeek = " + dayOfWeek);

        // Get DayOfWeek from string value
        dayOfWeek = DayOfWeek.valueOf("SATURDAY");
        System.out.println("dayOfWeek = " + dayOfWeek);

        // Get DayOfWeek of a date object
        LocalDate date = LocalDate.now();
        DayOfWeek dow = date.getDayOfWeek();

        System.out.println("Date  = " + date);
        System.out.println("Dow   = " + dow + "; value = " + dow.getValue());

        // Get DayOfWeek display name in different locale.
        Locale locale = new Locale("id", "ID");
        String indonesian = dow.getDisplayName(TextStyle.SHORT, locale);
        System.out.println("ID = " + indonesian);

        String germany = dow.getDisplayName(TextStyle.FULL, Locale.GERMANY);
        System.out.println("DE = " + germany);

        // Adding number of days to DayOfWeek enum.
        System.out.println("DayOfWeek.MONDAY.plus(4) = " + DayOfWeek.MONDAY.plus(4));
    }
}

And the result of the code above are:

dayOfWeek[0] = MONDAY; value = 1
dayOfWeek[1] = TUESDAY; value = 2
dayOfWeek[2] = WEDNESDAY; value = 3
dayOfWeek[3] = THURSDAY; value = 4
dayOfWeek[4] = FRIDAY; value = 5
dayOfWeek[5] = SATURDAY; value = 6
dayOfWeek[6] = SUNDAY; value = 7
dayOfWeek = MONDAY
dayOfWeek = SATURDAY
Date  = 2021-11-16
Dow   = TUESDAY; value = 2
ID = Sel
DE = Dienstag
DayOfWeek.MONDAY.plus(4) = FRIDAY