CODEWITHSUNDEEP
androidlistviewcomparator
iSee
iSee

Reputation: 604

Sort array list with two date objects in android

I have a ArrayList with custom objects. Each object has two date entities Call date and Appointment date. This information (along with others) are displayed in a list view and everything so far is working fine.

The Call date is never null and is always valid date from the server. However, the Appointment date can be null for a few entries. The date format for both Call date and Appointment date is the same (Thu Jan 01 00:00:00 GMT 1970)

The sorting should work like this:

Currently, I have got the Call date and Appointment date sorted by using two separate comparators. However, the Appointment date is in descending order instead of the ascending order (21st is showing on top, 19th below it and nulls at the end) as required.

The comparator code is below

    public class CallDateComparator implements Comparator< ListModel > {
        @Override
        public int compare(ListModel o1, ListModel o2) {
            if (o2.getCallDate() != null && o1. getCallDate() != null)
                return o2.getProspectDate().compareTo(o1.getProspectDate());
            else
                return 0;
        }
    }

    public class AppointmentDateComparator implements Comparator< ListModel > {
        @Override
        public int compare(ListModel o1, ListModel o2) {
            if (o2.getAppointmentDate() != null && o1.getAppointmentDate() != null)
                return o2.getAppointmentDate().compareTo(o1.getAppointmentDate());
            else
                return 0;
        }
    }

I sort the ArrayList by calling

Collections.sort(myList, new CallDateComparator());
Collections.sort(myList, new AppointmentDateComparator());

What needs to be changed above to get the appointment date sorted in ascending order and if it is null, just leave the earlier sorting intact?

Upvotes: 2

Views: 785

Answers (1)

CptEric
CptEric

Reputation: 907

my approach based on the format on the comments :

basically i'd do a bigger comparator rather than two different ones.

 public class CallDateComparator implements Comparator< ListModel > {
        @Override
        public int compare(ListModel o1, ListModel o2) {
            if (o2.getCallDate() != null && o1. getCallDate() != null)
                int i = o1.getProspectDate().compareTo(o2.getProspectDate();
                switch (i)
                  case -1: //o1 smaller than o2
                      return -1;
                    break;//this might be not necessary at all.
                  case 0: //both equal, so, same call date.
                        if(o1.getAppointmentDate() != null && o2.getAppointmentDate() == null)
                        {
                          return 1; // make o1 the bigger one.
                        }
                        else if(o1.getAppointmentDate() == null && o2.getAppointmentDate() != null)
                        {
                          return -1; // make o2 the bigger one.
                        }
                        else if(o1.getAppointmentDate() == null && o2.getAppointmentDate() == null)
                        {
                           return 0; //both are equally null.
                        }
                        else
                        {
                            return o1.getAppointmentDate().compareTo(o2.getAppointmentDate()); //compare then
                        }

                    break;
                  case 1: //o1 bigger than o2
                      return 1;
                    break;//this might be not necessary at all.
                  default:
                      return 0;
                    break;
            else
                return 0;
        }
    }

Upvotes: 1

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