How to Sort an Arraylist of Date in ascending and descending order which is in String format

Question

I have arrayLists of Dates which is in String format then how can I sort this arraylists,

ArrayList aryBeginDate;
ArrayList aryDu         


        

Answer 1

This will be very painful if you try to sort this yourself with Strings. I'd recommend you to parse the String to a Date (check JodaTime for a very convenient Date/Time tool) and then sort with java.util.Collections.sort().

Answer 2

You can use a Comparator to sort the list. Something like this:

Collections.sort(aryListBean, new Comparator<RowItem>() {
    @Override
    public int compare(RowItem r1, RowItem r2) {
        // Place your compare logic here
    }
});

Answer 3

Very Simple Answer:For Ascending just call this method:

Collections.sort(mArrayList, new OutcomeAscComparator());
public class OutcomeAscComparator implements Comparator<Select>
    {
        public int compare(Select left, Select right) {
            return left.getOutcome().compareTo(right.getOutcome());
        }
    }

Select is my model, For Descending:

Collections.sort(mArrayList, new OutcomeDescComparator());
public class OutcomeDescComparator implements Comparator<Select>
    {
        public int compare(Select left, Select right) {
            return right.getOutcome().compareTo(left.getOutcome());
        }
    }

Please dont forget to refresh your list view IF you want your list to be AScending and Descending

                mListView.invalidateViews();

                mAdapter.notifyDataSetChanged();

Answer 4

There is an in built function on ArrayList sort(). Since you are using String, this will work.

Answer 5

First convert the String in Date and create the arraylist. Then use the Collection sort method for sorting the arraylist.

Answer 6

Don't use a String when you want a Date. Use a Date. You should only transfom the Date to a String when displaying it. Otherwise, everywhere in the code, the date should of type Date. This is what allows sorting in chronological order, because dates have a natural order which is chronological.

So, once the RowItem has a startDate and an endDate, both being of type Date, you can sort a list of row items by start date using a simple comparator:

Collections.sort(rowItems, new Comparator<RowItem>() {
    @Override
    public int compare(RowItem r1, RowItem 2) {
        return r1.getStartDate().compareTo(r2.getStartDate());
    }
}); 

Also, fix your indentationof if/else blocks, because your way is really not readable:

if (aryBeginDate.equals(" ")) {
    row.setStartDate(" ");
} 
else {
    row.setStartDate(aryBeginDate.get(i).toString());
}