70. Converting between int and YearMonth

Consider that we have YearMonth.now() and we want to convert it to an integer (for example, this can be useful for storing a year/month date in a database using a numeric field). Check out the solution:

public static int to(YearMonth u) {
  return (int) u.getLong(ChronoField.PROLEPTIC_MONTH);
}

The proleptic-month is a java.time.temporal.TemporalField, which basically represents a date-time field such as month-of-year (our case) or minute-of-hour. The proleptic-month starts from 0 and counts the months sequentially from year 0. So, getLong() returns the value of the specified field (here, the proleptic-month) from this year-month as a long. We can cast this long to int since the proleptic-month shouldn’t go beyond the int domain (for instance, for 2023/2 the returned int is 24277).

Vice versa can be accomplished as follows:

public static YearMonth from(int t) {
  return YearMonth.of(1970, 1)
    .with(ChronoField.PROLEPTIC_MONTH...