How can I create a list of days, months, years from a calendar object in Java?

Question

I want to create a date widget for a form that has a selected list of months, days, years. since the list is different from month and year, I can’t write it down to 31 days. (for example, February has 28 days, not 30 or 31, but several years, even 29 days) How to use a calendar or joda to create these lists.

Answer 1

I highly recommend that you avoid the built-in date and time APIs in Java.

Use Joda Time instead . This library is similar to the one that (hopefully!) Will turn into Java 7 and will be much more pleasant to use than the built-in API.

Now, the main problem that you want to know about the number of days in a particular month?

EDIT: here is the code (with sample):

import org.joda.time.*;
import org.joda.time.chrono.*;

public class Test   
{
    public static void main(String[] args)
    {        
        System.out.println(getDaysInMonth(2009, 2));
    }

    public static int getDaysInMonth(int year, int month)
    {
        // If you want to use a different calendar system (e.g. Coptic)
        // this is the code to change.
        Chronology chrono = ISOChronology.getInstance();
        DateTimeField dayField = chrono.dayOfMonth();        
        LocalDate monthDate = new LocalDate(year, month, 1);
        return dayField.getMaximumValue(monthDate);
    }
}

Answer 2

The Calendar object will tell you the number of days in the current month with getActualMaximum(Calendar.DAY_OF_MONTH). See an example here .

From this, you can update your lists with every change.

Answer 3

java, swing web ui. .

Answer 4

:

String[] months = new DateFormatSymbols().getMonths();
    List<String> allMonths = new ArrayList<String>();
    for(String singleMonth: months){
        allMonths.add(singleMonth);
    }
    System.out.println(allMonths);

Answer 5

TL;DR

int lengthOfMonth = 
    YearMonth.from( 
                      LocalDate.now( ZoneId.of( "America/Montreal" ) ) 
                  )
             .lengthOfMonth() ;

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LocalDate

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ZoneId z = ZoneId.of( "America/Montreal" );
LocalDate today = LocalDate.now( z );

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int year = today.getYear();
int monthNumber = today.getMonthValue(); // 1-12 for January-December.
int dayOfMonth = today.getDayOfMonth();

LocalDate .

LocalDate ld = LocalDate.of( year , monthNumber , dayOfMonth );

YearMonth

, YearMonth.

YearMonth ym = YearMonth.from( ld );
int lengthOfMonth = ym.lengthOfMonth();

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