How to Sort Date in descending order From Arraylist Date in android?

Question

I have an ArrayList which stores Dates and I sorted them in descending order. Now I want to display them in a ListView. This is what I

Answer 1

Date's compareTo() you're using will work for ascending order.

To do descending, just reverse the value of compareTo() coming out. You can use a single Comparator class that takes in a flag/enum in the constructor that identifies the sort order

public int compare(MyObject lhs, MyObject rhs) {

    if(SortDirection.Ascending == m_sortDirection) {
        return lhs.MyDateTime.compareTo(rhs.MyDateTime);
    }

    return rhs.MyDateTime.compareTo(lhs.MyDateTime);
}

You need to call Collections.sort() to actually sort the list.

As a side note, I'm not sure why you're defining your map inside your for loop. I'm not exactly sure what your code is trying to do, but I assume you want to populate the indexed values from your for loop in to the map.

Answer 2

If date in string format convert it to date format for each object :

String argmodifiledDate = "2014-04-06 22:26:15";
SimpleDateFormat  format = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");  
            try
            {
                this.modifiledDate = format.parse(argmodifiledDate);
            }
            catch (ParseException e)
            {

                e.printStackTrace();
            }

Then sort the arraylist in descending order :

ArrayList<Document> lstDocument= this.objDocument.getArlstDocuments();
        Collections.sort(lstDocument, new Comparator<Document>() {
              public int compare(Document o1, Document o2) {
                  if (o1.getModifiledDate() == null || o2.getModifiledDate() == null)
                    return 0;     
                  return o2.getModifiledDate().compareTo(o1.getModifiledDate());
              }
            });

Answer 3

Just add like this in case 1: like this

 case 0:
     list = DBAdpter.requestUserData(assosiatetoken);
     Collections.sort(list, byDate);
     for (int i = 0; i < list.size(); i++) {
         if (list.get(i).lastModifiedDate != null) {
             lv.setAdapter(new MyListAdapter(
                     getApplicationContext(), list));
         }
     }
     break;

and put this method at end of the your class

static final Comparator<All_Request_data_dto> byDate = new Comparator<All_Request_data_dto>() {
    SimpleDateFormat sdf = new SimpleDateFormat("MM/dd/yyyy hh:mm:ss a");

    public int compare(All_Request_data_dto ord1, All_Request_data_dto ord2) {
        Date d1 = null;
        Date d2 = null;
        try {
            d1 = sdf.parse(ord1.lastModifiedDate);
            d2 = sdf.parse(ord2.lastModifiedDate);
        } catch (ParseException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }


        return (d1.getTime() > d2.getTime() ? -1 : 1);     //descending
    //  return (d1.getTime() > d2.getTime() ? 1 : -1);     //ascending
    }
};

Answer 4

Create Arraylist<Date> of Date class. And use Collections.sort() for ascending order.

See sort(List<T> list)

Sorts the specified list into ascending order, according to the natural ordering of its elements.

For Sort it in descending order See Collections.reverseOrder()

Collections.sort(yourList, Collections.reverseOrder());

Answer 5

Date is Comparable so just create list of List<Date> and sort it using Collections.sort(). And use Collections.reverseOrder() to get comparator in reverse ordering.

From Java Doc

Returns a comparator that imposes the reverse ordering of the specified comparator. If the specified comparator is null, this method is equivalent to reverseOrder() (in other words, it returns a comparator that imposes the reverse of the natural ordering on a collection of objects that implement the Comparable interface).

Answer 6

Easier alternative to above answers

1. If Object(Model Class/POJO) contains the date in String datatype.

   private void sortArray(ArrayList<myObject> arraylist) {
   SimpleDateFormat simpleDateFormat = new SimpleDateFormat("yyyy-MM-dd'T'HH:mm:ss.SSS'Z'"); //your own date format
   if (reports != null) {
       Collections.sort(arraylist, new Comparator<myObject>() {
           @Override
           public int compare(myObject o1, myObject o2) {
               try {
                   return simpleDateFormat.parse(o2.getCreated_at()).compareTo(simpleDateFormat.parse(o1.getCreated_at()));
               } catch (ParseException e) {
                   e.printStackTrace();
                   return 0;
               }
           }
       });
   }
   

2. If Object(Model Class/POJO) contains date in Date datatype

   private void sortArray(ArrayList<myObject> arrayList) {
   if (arrayList != null) {
       Collections.sort(arrayList, new Comparator<myObject>() {
           @Override
           public int compare(myObject o1, myObject o2) {
               return o2.getCreated_at().compareTo(o1.getCreated_at()); }
       });
   } }
   

The above code is for sorting the array in descending order of date, swap o1 and o2 for ascending order.