Sorting an ArrayList based on the sorting of another one

Question

I have an ArrayList<String>() in a class (GlobalDataHolder.cardNameAndDescription) and i want to sort it alphabetically but i also want to sort an ArrayList<Integer>() (UserBoxGlbImageAdapter.mGLBIcons) while sorting the previously mentioned arrayList.

Sidenote: Both arrays have a size of 3(0-2).

I am writing my own custom compare() method to do this but i am not achieving what i'm looking for.When i click on the button that runs the sorting code, the correct order doesn't get achieved unless i click the button 3 times although the String ArrayList does get Alphabetically sorted. So i figured that i just need to sort the arrays as many times as the arrays's size is(so 3 times).

To sum up, the String and Integer data should be in the same order since they depend on it's other but i can't get that to work for both arrays.

None of that worked. Can someone tell me what i'm doing wrong here with the 2nd array's sorting? Here's my code:

public class SortingDialog extends DialogFragment {

@NonNull
@Override
public Dialog onCreateDialog(Bundle savedInstanceState) {
    // Create a builder to make the dialog building process easier
    AlertDialog.Builder builder = new AlertDialog.Builder(getActivity());
    builder.setTitle("Sorting Dialog");
    builder.setSingleChoiceItems(R.array.sorting_options, 0,
            new DialogInterface.OnClickListener() {
                @Override
                public void onClick(DialogInterface dialogInterface, int i) {
                    if (i == 1) {
                        Toast.makeText(getActivity(), "2nd option Clicked", Toast.LENGTH_SHORT).show();
                        if (getActivity().getSupportFragmentManager().findFragmentByTag("GLOBAL_FRAGMENT") != null) {
                            sortGlobalListsBasedOnNameAndDesc();
                        }
                    }
                    for (int j = 0; j < GlobalDataHolder.cardNameAndDescription.size(); j++) {
                        Log.v("card_names", GlobalDataHolder.cardNameAndDescription.get(j));
                    }
                }
            });
    builder.setPositiveButton("OK", new DialogInterface.OnClickListener() {
        @Override
        public void onClick(DialogInterface dialogInterface, int i) {
            createToast();
            dismiss();
        }
    });
    builder.setNegativeButton("Cancel", new DialogInterface.OnClickListener() {
        @Override
        public void onClick(DialogInterface dialogInterface, int i) {
            dismiss();
        }
    });
    return builder.create();
}

private void sortGlobalListsBasedOnNameAndDesc() {
    if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.N) {
        GlobalDataHolder.cardNameAndDescription.sort(new Comparator<String>() {
            @Override
            public int compare(String s1, String s2) {
                int id1 = GlobalDataHolder.cardNameAndDescription.indexOf(s1);
                int id2 = GlobalDataHolder.cardNameAndDescription.indexOf(s2);

                if (s1.equals(s2)) {
                    return 0;
                } else if (s1.compareToIgnoreCase(s2) > 0) { //s1 is greater
                    //Collections.swap(UserBoxGlbImageAdapter.mGLBIcons,id2,id1);
                    swap(UserBoxGlbImageAdapter.mGLBIcons,id2,id1);
                    swap(GlobalDataHolder.cardNameAndDescription,id2,id1);
                    Log.d("case1","Called 1 time");
                    return 1;
                } else if (s1.compareToIgnoreCase(s2) < 0) { //s1 is smaller
                    //Collections.swap(UserBoxGlbImageAdapter.mGLBIcons,id1,id2);
                    swap(UserBoxGlbImageAdapter.mGLBIcons,id1,id2);
                    swap(GlobalDataHolder.cardNameAndDescription,id1,id2);
                    Log.d("case2","Called 1 time");
                    return -1;
                } else {
                    return 0;
                }
            }
        });
    }
}

private void swap(List list,int objIndex1, int objIndex2) {
    for (int i=0;i < list.size(); i++) {
        Collections.swap(list,objIndex1,objIndex2);
        UserBoxGlbImageAdapter.refreshFragmentView(UserBoxGLBFragment.getUserBoxAdapter());
    }
}

private void createToast() {
    Toast.makeText(getActivity(), "Cards sorted based on AVG Stats", Toast.LENGTH_SHORT).show();
}
}

Looks like your Strings and your integers are somehow connected. So you might want to create a custom class with a string and an interger variable, put objects of that one into a lost and sort it by the string value. Java is an object oriented programming language so make use of objects! — Timothy Truckle
– Timothy Truckle, Commented Feb 2, 2018 at 15:24
@TimothyTruckle those arrayLists are inside my database and it's crucial that they don't get mixed up as one object. — Stelios Papamichail
– Stelios Papamichail, Commented Feb 2, 2018 at 15:26
You will need some king of link between the Strings in the array and the integers ? You can do it in 2 steps,first sort the string array first and based on that order, sort the integer. — Dimitri
– Dimitri, Commented Feb 2, 2018 at 15:29
@Dimitri basically I'm already sorting the String List but I'm having trouble getting the 2nd list sorted correctly..I think I'm getting confused in the indexes part, how to get them correctly and use them to swap the 2nd List's elements in the right order. — Stelios Papamichail
– Stelios Papamichail, Commented Feb 2, 2018 at 19:25

Community · Accepted Answer · 2020-06-20 09:12:55Z

It is not difficult to sort a list of indexes instead of the list itself. From that you can easily reorder the list.

public class Test {
    List<String> testStrings = Arrays.asList(new String[]{"One", "Two", "Three", "Four", "Five", "Six", "Seven", "Eight", "Nine", "Ten"});
    List<Integer> testNumbers = Arrays.asList(new Integer[]{1, 2, 3, 4, 5, 6, 7, 8, 9, 10});

    static <T extends Comparable<T>> List<Integer> getSortOrder(List<T> list) {
        // Ints in increasing order from 0. One for each entry in the list.
        List<Integer> order = IntStream.rangeClosed(0, list.size() - 1).boxed().collect(Collectors.toList());
        Collections.sort(order, new Comparator<Integer>() {
            @Override
            public int compare(Integer o1, Integer o2) {
                // Comparing the contents of the list at the position of the integer.
                return list.get(o1).compareTo(list.get(o2));
            }
        });
        return order;
    }

    static <T> List<T> reorder(List<T> list, List<Integer> order) {
        return order.stream().map(i -> list.get(i)).collect(Collectors.toList());
    }

    public void test() {
        System.out.println("The strings: " + testStrings);
        List<Integer> sortOrder = getSortOrder(testStrings);
        System.out.println("The order they would be if they were sorted: " + sortOrder + " i.e. " + reorder(testStrings, sortOrder));
        List<Integer> reordered = reorder(testNumbers, sortOrder);
        System.out.println("Numbers in alphabetical order of their names: " + reordered);
    }

    public static void main(String[] args) {
        new Test().test();
        System.out.println("Hello");
    }
}

prints:

The strings: [One, Two, Three, Four, Five, Six, Seven, Eight, Nine, Ten]

The order they would be if they were sorted: [7, 4, 3, 8, 0, 6, 5, 9, 2, 1] i.e. [Eight, Five, Four, Nine, One, Seven, Six, Ten, Three, Two]

Numbers in alphabetical order of their names: [8, 5, 4, 9, 1, 7, 6, 10, 3, 2]

I leave it up to you to add a custom comparator if you feel you need one.

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