[FIXED] How to split array into different array or same array with different keys by checking the array value

Issue

I have an array that contains calendardays like this. this array may contain data from all the months.

calendarday: [CalendarDay{2017-8-13}, CalendarDay{2017-8-14}, CalendarDay{2017-9-18}, CalendarDay{2017-9-19}, CalendarDay{2017-10-15}, CalendarDay{2017-10-16}]

I want to split those array values by its months into different arrays or same arrays with different keys. like this

calendarday: [CalendarDay{2017-8-13}, CalendarDay{2017-8-14}]

calendardayone: [CalendarDay{2017-9-18}, CalendarDay{2017-9-19}]

or like this

calendarday: [
0:[CalendarDay{2017-8-13}, CalendarDay{2017-8-14}],
1:[CalendarDay{2017-9-18}, CalendarDay{2017-9-19}], 
2:[CalendarDay{2017-10-15}, CalendarDay{2017-10-16}]
]

One way I found is to check if condition for all the month and split those array. But I don't want to do that. Is there any alternative methods so that I will not have to check if condition for all months?

Solution

This is the solution I was thinking about: keep all the CalendarDay in a dictionary with the key being the month. So we start with something like this:

String[] array = {"CalendarDay{2017-8-13}", "CalendarDay{2017-8-14}", "CalendarDay{2017-9-18}", "CalendarDay{2017-9-19}", "CalendarDay{2017-10-15}", "CalendarDay{2017-10-16}"};

Then simply iterate the array, split each string and save it to the dictionary:

Map<String, ArrayList<String>> dictionary = new HashMap<String, ArrayList<String>>();
for (String currentString : array) {
    String month = currentString.split("-")[1];
    ArrayList<String> values = dictionary.get(month);
    if (values == null) {
        values = new ArrayList<String>();
    }
    values.add(currentString);
    dictionary.put(month, values);
}

And we end up with something like this:

{
    8=[CalendarDay{2017-8-13}, CalendarDay{2017-8-14}], 
    9=[CalendarDay{2017-9-18}, CalendarDay{2017-9-19}], 
    10=[CalendarDay{2017-10-15}, CalendarDay{2017-10-16}]
}

Answered By - Iulian Popescu
Answer Checked By - Clifford M. (JavaFixing Volunteer)