convert Date string to array of integers

Question

I have a string in the format: "YYYY-MM-DD" and I want to convert it into an array of integer

this is my code :

int year, month, day;
Date date = Calendar.getInstance().getTime();
DateFormat dateFormat = new SimpleDateFormat("yyyy-MM-dd");
String strDate = dateFormat.format(date);

for example, if the date is 2017-03-16 I want my array be like [2017,3,16].

Answer 1

Firstly i would say to use LocalDate , DateTimeFormatter from java-time API and stop using Calendar and SimpleDateFormat legacy date class

LocalDate currentDate = LocalDate.now();
String dateString = currentDate.format(DateTimeFormatter.ISO_DATE);

If you want to convert date string to int array, then split is based on - .

Integer[] array = 
    Arrays
    .stream( dateString.split("-") )
    .map( Integer::valueOf )
    .toArray( Integer[]::new )
;

Answer 2

This makes sense if all of your dates were preformatted as described in your question. But if you are using date Objects I would take advantage of the Java 8+ capabilities.

First, define a lambda to extract the parts and return an array. Note that you can add other date components or easily change the order in the array.

        Function<LocalDate, int[]> getParts =
                ld -> new int[] { ld.getDayOfMonth(),
                        ld.getMonthValue(), ld.getYear() };

Then you can apply it like so.

        LocalDate d = LocalDate.of(2020, 3, 15);
        int[] parts = getParts.apply(d);
        System.out.println(Arrays.toString(parts));

Prints

[15, 3, 2020]

Or this

        // create a list of LocalDate objects.
        List<LocalDate> localDates = List.of(
        LocalDate.of(2020, 3, 15), LocalDate.of(2020, 3, 16));
        // and convert to a list of arrays of date attributes.
        List<int[]> dates = localDates.stream().map(getParts::apply)
                  .collect(Collectors.toList());
        dates.forEach(a->System.out.println(Arrays.toString(a)));

Prints

[15, 3, 2020]
[16, 3, 2020]

Another advantage of this is that you don't have to ensure the format is the same from date to date.

Answer 3

It's very quick and easy. If you are bound to use an array, the solution => import these=>

    import java.text.DateFormat;
    import java.text.SimpleDateFormat;
    import java.util.Calendar;
    import java.util.Date;

then in your main or other method =>

    int[] dateArray = new int[100]; // or your desired size

    Date date = Calendar.getInstance().getTime();
    DateFormat dateFormat = new SimpleDateFormat("yyyy-MM-dd");
    String strDate = dateFormat.format(date);

    String[] line = strDate.split("-");

    for (int i = 0; i < line.length; i++)
    {
        dateArray[i] = Integer.parseInt(line[i]);
    }

should do it.