arrange cutom Arraylist according to time column

Question

I Have one Custom arraylist which contains multiple parameters along with time.

I want to sort that list according to time Parameter in asending and desending format

I searched alot Here are some links Sort objects in ArrayList by date?

and many more but none worked

Here is my code

function calling on Click

 private void callTimeSorting(ArrayList<ObjectClass>solutions){
    try{
        ArrayList<ObjectClass> tempList = new ArrayList<>();
        if (tempList.size() > 0){tempList.clear();}
        tempList.addAll(solutions);
        if (mTimeTag == 1) {
            if (!mAsendingTime) {
                Collections.sort(tempList, AsendingTimeComparator);
                mAsendingTime = true;
                mAdapter.notify();
            } else {
                Collections.sort(tempList, DesendingTimeComparator);
                mAsendingTime = false;
            }

        }
 }

OnClick method

 @Override
public void onClick(View view) {
    int id = view.getId();
    switch (id) {
       case R.id.tvTimings :
            mTimeTag =  1 ;
            callTimeSorting(mSolutions) ;
            mAdapter.notifyDataSetChanged();
            break;


 }}

AsendingComparator

  private static Comparator<ObjectClass> AsendingTimeComparator = new Comparator<ObjectClass>() {
    @Override
    public int compare(ObjectClass solution1, ObjectClass solution2) {
        String time1 = solution1.getDepartureDateTime();
        String time2 = solution2.getDepartureDateTime();
        return time1.compareTo(time2);//asending
    }
};

private static Comparator<ObjectClass> DesendingTimeComparator = new Comparator<ObjectClass>() {
    @Override
    public int compare(ObjectClass solution1, ObjectClass solution2) {
        String time1 = solution1.getDepartureDateTime();
        String time2 = solution2.getDepartureDateTime();
        return time2.compareTo(time1);//descending

    }



};

I dont know why my sorted list is not attaching to recyclerView??

in set adapter which list you are using? – Pavya Feb 19 '18 at 11:14 — Pavya, Feb 19 '18 at 11:14

score 3 · Accepted Answer · answered Feb 19 '18 at 11:16

Use the original list used in Adapter, not the temp one

 private void callTimeSorting(ArrayList<ObjectClass>solutions){
        try{
            ArrayList<ObjectClass> tempList = new ArrayList<>();
            tempList.addAll(solutions);
            solutions.clear();
            if (mTimeTag == 1) {
                if (!mAsendingTime) {
                    Collections.sort(tempList, AsendingTimeComparator);
                    mAsendingTime = true;
                } else {
                    Collections.sort(tempList, DesendingTimeComparator);
                    mAsendingTime = false;
                }
              solutions.addAll(tempList);
              mAdapter.notifyDataSetChanged();
            }
     }

score 2 · Answer 2 · answered Feb 19 '18 at 11:19

Your list is not getting sorted because you are sorting the tempList:

Collections.sort(tempList, AsendingTimeComparator);

And not the actual list your adapter is using i.e solutions.

You should not use templist and directly sort solutions.

private void callTimeSorting(ArrayList<ObjectClass>solutions){
    try{
        if (mTimeTag == 1) {
            if (!mAsendingTime) {
                Collections.sort(solutions, AsendingTimeComparator);
                mAsendingTime = true;
                mAdapter.notify();
            } else {
                Collections.sort(solutions, DesendingTimeComparator);
                mAsendingTime = false;
            }

        }
 }

score 1 · Answer 3 · answered Feb 19 '18 at 11:19

Use the reference of the mList ... through out your code dont initialize it again.. use clear() instead of new Arraylist<> and dont assign any other reference to the list like list = new_List;

The mAdapter would lose reference of the list... and wont work accordingly.. (notifyDataSetChanged() wont work.

arrange cutom Arraylist according to time column

3 Answers3