My Activity has RecyclerView which items are consisting only of EditTexts. I did it for improving overall performance over one, simple EditText. These items at start are set like that:

    public void setText(String text) {
        List<String> strings = UtilsJava.splitInParts(text, 2000, 50, {'.', ':', '?', '!', ';', ' '});
        if (strings.isEmpty()) {
            strings.add(text);
        }
        adapter.setItems(strings);
        adapter.fillBigTextModelList(strings);
    }

(...)

    public static List<String> splitInParts(String str, int len, int m, char[] splitChars) {
        List<String> result = new ArrayList<>();
        int cutStart = 0;
        for (int i = 0; i < (int) Math.ceil((double) str.length() / len); i++) {
            int cutEnd = Math.min(str.length(), (i + 1) * len);
            if (cutEnd != str.length() && (cutEnd + m) < str.length()) {
                String section = str.substring(cutEnd - m, cutEnd + m);
                int index = indexOf(section, splitChars);
                cutEnd = cutEnd - m + index + 1;
            }
            result.add(str.substring(cutStart, cutEnd));
            cutStart = cutEnd;
        }
        return result;
    }

So far so good. In my example I have text that is split into 4 items. Now I want to remove a part of zero item, all second item, and a part of third item. I created a custom solution for that (because a system one does not go through multi EditText). I simply set start index and end index by simple click. and choose with specific button which one is this selection. Now that I have start index and end index I call highlightSelection() :

    public void highlightSelection(int startIndexTotal, int endIndexTotal) {
        Predicate<BigTextModel> predicate1 = o -> o.getStartIndex() <= endIndexTotal;
        Predicate<BigTextModel> predicate2 = o -> o.getEndIndex() >= startIndexTotal;

        int vhIndex = Stream.of(bigTextModelList).filter(predicate1).filter(predicate2).findFirst().get().getVhIndex();
        BigTextModel bigTextModel = bigTextModelList.get(vhIndex);

        List<String> items = new ArrayList<>();

        int index3 = 0;

        if (isSelectionWithinOneVh(startIndexTotal, endIndexTotal, bigTextModel)) {
            // it works
        } else if (isSelectionWithinMoreVhs(startIndexTotal, endIndexTotal, bigTextModel)) {
            int index1;
            int index2 = 0;
            int totalProcessedLength = 0;
            boolean isNoVhIndexChanged = false;
            for (BigTextModel bigTextModel1 : bigTextModelList) {
                totalProcessedLength += textList.get(bigTextModel1.getVhIndex()).length();

                if (bigTextModel1.getVhIndex() == 0) {
                    index1 = startIndexTotal;
                    index2 = textList.get(0).length();
                    String b = getJoinedText().substring(0, index1);
                    items.add(b);
                }

                else {
                    if (totalProcessedLength < endIndexTotal) {
                        index2 += textList.get(bigTextModel1.getVhIndex()).length();
                    } else {
                        if ((textList.get(bigTextModel1.getVhIndex()).length() - Math.abs(totalProcessedLength - endIndexTotal)) > 0) {
                            index2 += (textList.get(bigTextModel1.getVhIndex()).length() - Math.abs(totalProcessedLength - endIndexTotal));
                            String item = getJoinedText().substring(index2, index2 + Math.abs(totalProcessedLength - endIndexTotal));
                            index2 = index2 + Math.abs(totalProcessedLength - endIndexTotal);
                            items.add(item);
                        } else if (!isNoVhIndexChanged) {
                            index2 = index3;
                            String item = getJoinedText().substring(index2);
                            items.add(item);
                            isNoVhIndexChanged = true;
                        }
                    }
                }
            }
        }

        setItems(items);
    }

    public void setItems(List<String> items) {
        textList.clear();
        textList.addAll(items);
        notifyDataSetChanged();
    }

When I debugged these items, they seemed to be correct – there were 3 items, as I expected.

Now for example if I remove a single character from first item and then I remove a single character form third item then when I call a method getAllDescChanges()

private LinkedList<Diff> getAllDescChanges() {

    (...)

    String savedNoteDesc = bundle.getString("noteDesc");
    editedNoteDesc = String.join("", adapter.getTextList());

    DiffMatchPatch dmp = new DiffMatchPatch();
    return dmp.diff_main(savedNoteDesc, editedNoteDesc);
}

I get 9 changes from which 5th, 6th definitely should’t be here and 7th has wrong index – its startIndex should be something like 7003. This DiffMatchPatch is a github project from here: github_link. Here is a screenshot from debugging this method:

From what I found out is that:

1. if I remove only single character from first item and then from last item without multi removing multi text – DiffMatchPatch shows everything correctly

2. deletion these two characters + deleting from within index 0 – to within index 1 – there’s no problem,

3. deletion these two characters + deleting from within index0 – to within index 2 – there’s problem,

4. deletion these two characters + deletion from within index 0 – to within index 3 – there’s problem

So the question is how to avoid having these two weird changes and to solve this wrong startIndex of 7th change?

I tried:

1. In highlightSelection() I tried working directly on listItem items by setting and removing item – didn’t work

2. In highlightSelection() I tried to create new list and once was ready replace adapter’s listItem with this list (like in attached code)

3. and some other not working solutions that I already have forgotten because it’s been a few weeks since I started working on it

I’m struggling with this bug for about a few weeks without any progress. So thank you so so much if you are willing to help!