Date Sorting ArrayList

Question

Folks, I have a weird requirement. I have an Object which consists of a Date reference better known as endDate. Along with this there is another String field called as the status which picks values like 'Soon', 'Ended' and 'Closed' Such objects are in an ArrayList.

I want to implement a sorting Strategy on this.

First sorting to apply is based on Elapsed time. I want to First sort on EndDate, the difference of which is closest to now should be ranked 1st. i.e if the current Time is Sep 3,2015 7:34 PM IST and there exists an object with endDate as Sep 3,2015 7:36 PM IST.

Second is on the status the logic being all object with soon should appear first, then the ended ones and then closed.

Example : if the Input is

[0]( Sep 1,2015 10:36 PM IST ,ended)
[1]( Sep 3,2015 7:36 PM IST , soon )
[2]( Aug 29,2015 11:16 AM IST , closed)
[3]( Sep 7,2015 12:00 PM IST , soon )
[4]( Sep 1,2015 12:12 PM IST , ended)

Then the output should be

[0]( Sep 3,2015 7:36 PM IST , soon)
[1]( Sep 7,2015 12:00 PM IST , soon)
[2]( Sep 1,2015 10:36 PM IST ,ended)
[3]( Sep 1,2015 12:12 PM IST , ended)
[4]( Aug 29,2015 11:16 AM IST , closed)

Note : Timestamps used here are for representational purpose only

CODE : The compare implementation inside the comparator, The timestamps are read as GMT.

@Override
            public int compare(JSONObject a, JSONObject b) {

                SimpleDateFormat dateFormatGmt = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
                dateFormatGmt.setTimeZone(TimeZone.getTimeZone("GMT"));
                SimpleDateFormat dateFormatLocal = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");

                try {
                    Date currentdate = dateFormatLocal.parse( dateFormatGmt.format(new Date()));
                } catch (ParseException e1) {
                    e1.printStackTrace();
                }

                try {
                    Date betEnds1 = dateFormatLocal.parse((String) a.get(KEY_NAME));
                    Date betEnds2 = dateFormatLocal.parse((String) b.get(KEY_NAME));


                return betEnds1.compareTo(betEnds2);
                } 
                catch (JSONException e) {
                    return -1;
                } catch (ParseException e) {
                    return -1;
                }
            }

If you haven't already. Have a look at the Comparator class. https://docs.oracle.com/javase/8/docs/api/java/util/Comparator.html. You can use it with Arrays.sort — Buhb, Sep 03 '15 at 14:22
Since the status strings are all going to be predetermined, why not use an enum? — , Sep 03 '15 at 14:23
@Turtle i had written a comparator but its a simple one. It takes the long representation of time, compares them and returns the ordering. but as i want to have the elapsed time more than 0 first in the list i had put this question. The comparison at which the Objects are sorted is with respect to current time. And the second sort is on Status — shridatt, Sep 03 '15 at 15:20

score 3 · Answer 1 · answered Sep 03 '15 at 14:27

3

Implement a Comparator and make it sort your items as desired. The compare(a,b) method will take two objects and you can either return -1, 0 or +1, depending on whether two items are the same or one is bigger/smaller than the other.

answered Sep 03 '15 at 14:27

user1438038

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Date Sorting ArrayList

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