How to Sort Date in a Custom Arraylist in Android Studio?

Question

I am adding a feature in my app which lets the user fill entries for past dates, if today is 14/03/2020 then it lets you fill entries for 10/03/2020(or any other date). But I am Having a problem with sorting my arraylist such that all the entries with same dates are together in the arraylist.

I show the entries to the user in a custom ListView and so to make my app user friendly I want to make all those entries with the same date to appear together.

I have a custom arraylist which accepts a Expense Name(String),Amount(String) and Date(String)

ArrayList<ExpenseData> customArrayList=new ArrayList<ExpenseData>();

If you need any other information please ask... Thank You!

score 2 · Accepted Answer · answered Mar 14 '20 at 13:00

You can use below method to sort your list by date.

 Collections.sort(list, (item1, item2) -> {
            Date date1 = stringToDate(item1.getDate());
            Date date2 = stringToDate(item2.getDate());

            if (date1 != null && date2 != null) {
                boolean b1;
                boolean b2;
                if (isAscending) {
                    b1 = date2.after(date1);
                    b2 = date2.before(date1);
                }else {
                    b1 = date1.after(date2);
                    b2 = date1.before(date2);
                }

                if (b1 != b2) {
                    if (b1) {
                        return -1;
                    }
                    if (!b1) {
                        return 1;
                    }
                }
            }
            return 0;
        });

public static Date stringToDate(String strDate) {
        if (strDate == null)
            return null;

        // change the date format whatever you have used in your model class.
        SimpleDateFormat format = new SimpleDateFormat("MMM dd, yyyy hh:mm:ss a", Locale.US);
        Date date = null;
        try {
            date = format.parse(strDate);
            System.out.println(date);
        } catch (ParseException e) {
            e.printStackTrace();
        }
        return date;
    }

isAscending is boolean if you want to sort in ascending order(old date will be first in list). You can remove this condition and only use the block which you need. — DB377, Mar 14 '20 at 13:13

score 1 · Answer 2 · answered Mar 14 '20 at 13:06

1

It is very bad practice to directly store Date or Time as String.

Instead you have store the Date or Time as Epoch value (Integer). That way you will have a lot of flexibility while displaying as well as Sorting or other operations.

And you can sort it in Increasing order for Old to New, Decreasing order for New to Old.

Hope it helps

answered Mar 14 '20 at 13:06

Susheel Karam

837
7
16

Okay Thank You! I will take care of it – Xen Mar 14 '20 at 13:23

score 0 · Answer 3 · answered Mar 14 '20 at 13:34

You can easily sort the data in the required format by using Comparable or Comparator.

Your ExpenseData class which contains the date can implement Comparable interface and override the compareTo() method, where you define the logic to sort the dates.

For complete and detailed tutorial refer below this.

How to Sort Date in a Custom Arraylist in Android Studio?

3 Answers3