javatimeYearMonth

javatimeYearMonth is a class in the java.time package introduced in Java 8 as part of the Date and Time API. It represents a specific year and month without a day component, such as 2024‑01 for January 2024. This class is immutable and thread‑safe, making it suitable for concurrent applications that need to manipulate dates at the year‑month level.

The primary constructor is YearMonth.of(int year, int month), where month is either an int between 1 and 12 or a java.time.Month enum value. There are also factory methods from(TemporalAccessor) and parse(CharSequence) which can create a YearMonth instance from most temporal objects or from a textual representation following the ISO-8601 pattern “YYYY‑MM”. The value can be converted to other temporal types: toLocalDate() creates a LocalDate at the first day of the month and toYearMonth() simply returns the instance itself.

YearMonth provides arithmetic operations such as plusYears, plusMonths, minusYears and minusMonths, enabling chronological calculations over months. The plus and minus methods handle overflow automatically, e.g., adding one month to 2023‑12 returns 2024‑01. Shifting operations like atDay(int dayOfMonth) produce a LocalDate in the current YearMonth, allowing creation of date objects for specific days within that month.

Comparison methods include isBefore, isAfter, and compareTo, facilitating sorting of YearMonth instances. Equality and hash code are based solely on the year and month values, enabling use in collections as keys.

Formatting is achieved via DateTimeFormatter. The built‑in formatters, such as ISO_DATE, produce strings like “2024‑01”. Custom patterns can format the year, month, or display styled month names.

Because YearMonth contains no time‑zone information, it is unaffected by daylight‑saving time transitions or locale changes. It is ideal for reporting, scheduling, payroll calculations, and any domain logic where only year and month matter.