Java Month Enum
Last modified: April 16, 2025
The java.time.Month enum represents the twelve months of the year.
It is part of the Java Date and Time API introduced in Java 8. Each enum constant
provides useful methods for working with months.
Month is immutable and thread-safe. It provides methods to get month
names, lengths, and values. The enum works seamlessly with other date-time
classes like LocalDate and YearMonth.
Month Enum Overview
The Month enum contains twelve constants from JANUARY to DECEMBER.
Each constant has methods to query month properties and perform conversions.
The enum follows the ISO-8601 calendar system.
public enum Month implements TemporalAccessor, TemporalAdjuster {
JANUARY, FEBRUARY, MARCH, APRIL, MAY, JUNE,
JULY, AUGUST, SEPTEMBER, OCTOBER, NOVEMBER, DECEMBER;
public int getValue();
public String getDisplayName(TextStyle style, Locale locale);
public int length(boolean leapYear);
public int minLength();
public int maxLength();
public Month firstMonthOfQuarter();
public Month plus(long months);
public Month minus(long months);
}
The code above shows the structure and key methods of the Month
enum. These methods allow querying month properties and performing calculations.
The enum provides both numerical and textual representations of months.
Getting Month Values
Each Month constant has a numerical value from 1 (January) to 12
(December). The getValue method returns this value. This is useful
for compatibility with older APIs that use month numbers.
package com.zetcode;
import java.time.Month;
public class Main {
public static void main(String[] args) {
// Get month values
System.out.println("January value: " + Month.JANUARY.getValue());
System.out.println("December value: " + Month.DECEMBER.getValue());
// Get month from value
Month month = Month.of(6);
System.out.println("Month 6: " + month);
// Get current month
Month current = Month.from(java.time.LocalDate.now());
System.out.println("Current month: " + current);
}
}
This example demonstrates basic operations with Month values. The
of method creates a Month from its numerical value. The
from method extracts Month from other date-time objects.
Displaying Month Names
The getDisplayName method provides localized month names in various
text styles. This is useful for user interfaces that need to display month names
in different formats and languages.
package com.zetcode;
import java.time.Month;
import java.time.format.TextStyle;
import java.util.Locale;
public class Main {
public static void main(String[] args) {
// Full name in English
String fullName = Month.AUGUST.getDisplayName(
TextStyle.FULL, Locale.ENGLISH);
System.out.println("Full name: " + fullName);
// Short name in French
String shortName = Month.AUGUST.getDisplayName(
TextStyle.SHORT, Locale.FRENCH);
System.out.println("Short name in French: " + shortName);
// Narrow name in German
String narrowName = Month.AUGUST.getDisplayName(
TextStyle.NARROW, Locale.GERMAN);
System.out.println("Narrow name in German: " + narrowName);
}
}
This example shows different ways to display month names. The
TextStyle enum controls the name format (FULL, SHORT, NARROW).
The Locale parameter provides localization support.
Working with Month Lengths
The Month enum provides methods to query month lengths. These
methods are essential for date calculations and validation. February's length
depends on whether it's a leap year.
package com.zetcode;
import java.time.Month;
public class Main {
public static void main(String[] args) {
// Regular month lengths
System.out.println("January days: " + Month.JANUARY.length(false));
System.out.println("April days: " + Month.APRIL.length(false));
// February in leap year
System.out.println("February in leap year: " +
Month.FEBRUARY.length(true));
// Min and max lengths
System.out.println("February min days: " +
Month.FEBRUARY.minLength());
System.out.println("February max days: " +
Month.FEBRUARY.maxLength());
}
}
This example demonstrates month length queries. Most months have fixed lengths,
but February varies. The minLength and maxLength
methods provide bounds for February's length.
Month Arithmetic
The Month enum supports arithmetic operations through
plus and minus methods. These operations wrap around
at year boundaries, making them useful for month-based calculations.
package com.zetcode;
import java.time.Month;
public class Main {
public static void main(String[] args) {
// Basic arithmetic
Month nextMonth = Month.JANUARY.plus(1);
System.out.println("January + 1: " + nextMonth);
Month prevMonth = Month.JANUARY.minus(1);
System.out.println("January - 1: " + prevMonth);
// Wrapping around year boundary
Month decPlus2 = Month.DECEMBER.plus(2);
System.out.println("December + 2: " + decPlus2);
Month janMinus3 = Month.JANUARY.minus(3);
System.out.println("January - 3: " + janMinus3);
// Large values
Month janPlus25 = Month.JANUARY.plus(25);
System.out.println("January + 25: " + janPlus25);
}
}
This example shows month arithmetic operations. The calculations automatically wrap around at year boundaries. Adding 1 to December gives January, and subtracting 1 from January gives December.
Working with Quarters
The firstMonthOfQuarter method returns the first month of each
quarter. This is useful for financial and business applications that organize
time by quarters.
package com.zetcode;
import java.time.Month;
public class Main {
public static void main(String[] args) {
// Get first month of quarters
System.out.println("Q1 starts with: " +
Month.JANUARY.firstMonthOfQuarter());
System.out.println("Q2 starts with: " +
Month.APRIL.firstMonthOfQuarter());
System.out.println("Q3 starts with: " +
Month.JULY.firstMonthOfQuarter());
System.out.println("Q4 starts with: " +
Month.OCTOBER.firstMonthOfQuarter());
// Any month in quarter returns same result
System.out.println("May's quarter starts with: " +
Month.MAY.firstMonthOfQuarter());
}
}
This example demonstrates quarter-related operations. Each quarter consists of three months, and the method returns the first month regardless of which month in the quarter is used to call it.
Using Month with LocalDate
The Month enum works seamlessly with LocalDate.
This combination is powerful for date manipulation and querying. The examples
show common operations between these classes.
package com.zetcode;
import java.time.LocalDate;
import java.time.Month;
import java.time.Year;
public class Main {
public static void main(String[] args) {
// Create date with Month enum
LocalDate date1 = LocalDate.of(2025, Month.JANUARY, 15);
System.out.println("Date with Month enum: " + date1);
// Get month from date
Month month = date1.getMonth();
System.out.println("Month from date: " + month);
// Create date at start of month
LocalDate startOfMonth = Year.now().atMonth(Month.MARCH).atDay(1);
System.out.println("Start of March: " + startOfMonth);
// Check if month has 31 days
boolean has31Days = month.maxLength() == 31;
System.out.println(month + " has 31 days: " + has31Days);
}
}
This example shows integration between Month and
LocalDate. The Month enum provides type safety when creating
dates. The example also demonstrates querying month properties from dates.
Source
In this article, we've covered the essential methods and features of the Java Month enum. Understanding these concepts is crucial for date handling in modern Java applications.
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