I'm using the Java 8 time library to determine the previous weeks and year from today's date and then store those values in a map. I think I've figured out how to properly get the weeks, but I'm not entirely sure what the correct way is to get the year. Current code below:
int weeksLimit = 5; // this value is passed into the method, but just setting it here as an example
Map<Integer, Integer> yearWeeks = new HashMap<Integer, Integer>();
LocalDate ld = LocalDate.now();
WeekFields weekFields = WeekFields.of(DayOfWeek.SUNDAY, 4);
for (int i = weeksLimit; i > 0; i--) {
LocalDate pastDate = ld.minusWeeks(i);
yearWeeks.put(pastDate.getYear(), pastDate.get(weekFields.weekOfWeekBasedYear()));
}
I don't believe pastDate.getYear() is the correct usage. As the result I want is something along the lines of:
Could someone please help me figure out how to correctly get the year I want?
I can’t tell which is the right data structure for your purpose. A map with year as key and week as value won’t do for holding your example data. In your example year 2020 comes three times, but a given key can appear only once in a map. In the following example I am assuming a map that maps each week based year to a list of week numbers for that year.
WeekFields weekFields = WeekFields.of(Locale.forLanguageTag("mt_MT"));
int weeksLimit = 5; // this value is passed into the method, but just setting it here as an example
LocalDate today = LocalDate.now(ZoneId.of("Europe/Malta"));
Map<Integer, List<Integer>> yearWeeks = IntStream.rangeClosed(1, weeksLimit)
.mapToObj(i -> today.minusWeeks(i))
.collect(Collectors.groupingBy(ld -> ld.get(weekFields.weekBasedYear()),
Collectors.mapping(ld -> ld.get(weekFields.weekOfWeekBasedYear()),
Collectors.toList())));
System.out.println(yearWeeks);
When I ran the snippet just now, the output was:
{2019=[52, 51], 2020=[3, 2, 1]}
I don’t expect to be there yet, but I am not putting more effort into this until I understand your requirements more clearly.