How to find the day of week (Monday, tuesday etc.) of the first day of a month in Java?

Question

How to find, let's say, what day of the week is June 1st in Java?

Do you have to use `Date` and `Calendar` and what have you tried so far? — deHaar, Jun 23 '21 at 08:02
Please stop! You should definitely prefer **not** to use `Calendar`. That class is poorly designed and long outdated. Instead use `LocalDate` and `DayOfWeek`, both from [java.time, the modern Java date and time API](https://docs.oracle.com/javase/tutorial/datetime/). — Ole V.V., Jun 23 '21 at 10:34
`YearMonth.now(ZoneId.systemDefault()).atDay(1).getDayOfWeek()`. Running in this month it yields `TUESDAY`. — Ole V.V., Jun 23 '21 at 10:37
Welcome to Stack Overflow. Please learn that you are supposed to search before asking a question here and when you post a question, tell us what your search brought up and specify how it fell short of solving your problem. It’s for your own sake since (1) you often find a better answer faster that way (2) it allows us to give preciser and more focused answers. It also tends to prevent or at least reduce the number of downvotes. — Ole V.V., Jun 23 '21 at 10:42
Can you combine the answers from the follwing two questions? [Get first date of current month in java](https://stackoverflow.com/questions/14241836/get-first-date-of-current-month-in-java) and [How to determine day of week by passing specific date?](https://stackoverflow.com/questions/5270272/how-to-determine-day-of-week-by-passing-specific-date) I recommend [this answer](https://stackoverflow.com/a/26265701/5772882) and [this one](https://stackoverflow.com/a/26265701/5772882), both by Basil Bourque using java.time. — Ole V.V., Jun 23 '21 at 13:11

LenglBoy · Answer 1 · 2021-06-23T08:27:10.507

2

Using java.util.Date (legacy time/date classes):

Date date=new Date(); // today
Date date = new Date(2021, 06, 23); // custom
Calendar c = Calendar.getInstance();
c.setTime(date);
int dayOfWeek = c.get(Calendar.DAY_OF_WEEK); // 3
String dayWeekText = new SimpleDateFormat("EEEE").format(date); //TUESDAY

Using java.time.LocalDate:

LocalDate localDate = LocalDate.of(2021, 06, 23); // custom
LocalDate localDate = LocalDate.now(); // today
java.time.DayOfWeek dayOfWeek = localDate.getDayOfWeek();
dayOfWeek.getValue(); // 4
dayOfWeek.toString(); // WEDNESDAY

edited Jun 23 '21 at 08:27

answered Jun 23 '21 at 08:04

LenglBoy

297
2
8

What if I wanted a month to be a variable. i.e. Return the day of the week of the first day of the current month. For example if I ran this function on june, this return the day of 1st june, when I run this function on July, this returns the day of 1st july – drugsrbad Jun 23 '21 at 10:08
1

@drugsrbad Feel free to use the custom/overloaded constructors and add the information. You can use it like: `LocalDate.of(2021, month, 01);` where day is fixed to be 1, the month can be any value by a variable and year is fixed. If you want the year to be dynamic use: `LocalDate.of(LocalDate.now().getYear(), month, 01);` If it should always take just the 1st date of current mont it would be: `LocalDate.of(LocalDate.now().getYear(), LocalDate.now().getMonth(), 01);` – LenglBoy Jun 23 '21 at 10:17
2

Even if the reader insists on using the poorly designed and long outdated `Date` class (which is not indicated in the question and is not recommended), you should stay **far** away from the three-arg `Date` constructor. It has been deprecated for 24 years because it works unreliably across time zones. – Ole V.V. Jun 23 '21 at 10:39

score 1 · Answer 2 · answered Jun 23 '21 at 08:42

For the case you want the day of week as String, you can use code from this example:

public static void main(String[] args) {
    // provide the date (alternatively, parse it from a String)
    LocalDate firstOfJune2021 = LocalDate.of(2021, 6, 1);
    // then get the day of week by means of a DateTimeFormatter
    String dayOfWeek = firstOfJune2021.format(
                            DateTimeFormatter.ofPattern("EEEE", Locale.ENGLISH)
                       );
    // as an alternative, you can get it by chain-calling some methods
    String altDayOfWeek = firstOfJune2021.getDayOfWeek()
                                         .getDisplayName(TextStyle.FULL, Locale.ENGLISH);
    // print the results
    System.out.println(firstOfJune2021 + " was a " + dayOfWeek);
    System.out.println(firstOfJune2021 + " was a " + altDayOfWeek);
}

This code produces the following output:

2021-06-01 was a Tuesday
2021-06-01 was a Tuesday

There's an enum DayOfWeek, which is actually the result type of LocalDate.getDayOfWeek().
It is not clear from your question if you want to use a value like an int, the enum or a String representation...

score 0 · Answer 3 · answered Jun 23 '21 at 08:07

It depends on which version of Java and which types you are using. A simple way to determine the day of the week since Java 8 using LocalDate would look as follows:

LocalDate date = LocalDate.of(2021, 6, 1);
System.out.println(date.getDayOfWeek().getValue());

The returning values are numbered from 1 (Monday) to 7 (Sunday).

A good overview of different approaches can be found in How to determine day of week on Baeldung.

How to find the day of week (Monday, tuesday etc.) of the first day of a month in Java?

3 Answers3