Why is search text highlighting in RecyclerView using ListAdapter failing to display correctly on some CardViews?

Android: Resolving ForegroundColorSpan Search Text Highlighting Issue with RecyclerView and ListAdapter

Problem Description

A RecyclerView list of CardViews is located beneath a SearchView within a Toolbar. Search text highlighting with Color.GREEN is intended to be implemented in the ListAdapter's onBindViewHolder() method. However, the first CardView in the RecyclerView list and other subsequent CardViews often fail to display highlighted text, hindering search text visibility. This issue may be linked to using ListAdapter as the Adapter.

Code Snippets

MainActivity

@Override
public boolean onCreateOptionsMenu(Menu menu) {
  mSearchView.setOnQueryTextListener(new SearchView.OnQueryTextListener() {
    @Override
    public boolean onQueryTextSubmit(String query) {
      return false;
    }

    @Override
    public boolean onQueryTextChange(String newText) {
      filter(newText);
      return false;
    }
  });
  return true;
}

private void filter(String searchText) {
  ArrayList<Card> searchList = new ArrayList<>();
  for (Card cardItem : mCards) {
    if (cardItem.getTodo().toLowerCase(Locale.US).contains(searchText)) {
      searchList.add(cardItem);
    }
  }
  if (!searchList.isEmpty()) {
    adapter.setFilter(searchList, searchText);
  }
}

ListAdapter

public class CardRVAdapter extends ListAdapter<Card, CardRVAdapter.ViewHolder> {
  private String searchString = "";
  public Spannable spannable;

  public void setFilter(List<Card> newSearchList, String adapSearchText) {
    if (newSearchList != null && !newSearchList.isEmpty()) {
      this.searchString = adapSearchText.toLowerCase(Locale.US);
      ArrayList<Card> tempList = new ArrayList<>(newSearchList);
      submitList(tempList);
    }
  }

  public class ViewHolder extends RecyclerView.ViewHolder {
    TextView carBlankText2;  // displays text in the CardView and is matched against the search text input.
    ForegroundColorSpan fcs = new ForegroundColorSpan(Color.GREEN);

    public ForegroundColorSpan getFCS() {
      return fcs;
    }
  }

  public ViewHolder(@NonNull final View itemView) {
    super(itemView);
    cardBlankText2 = itemView.findViewById(R.id.cardBlankText2);
  }

  void bindData(Card card, final int position) {
    spannable = Spannable.Factory.getInstance().newSpannable(cardBlankText2.getText().toString());

    // Get any previous spans and remove them
    ForegroundColorSpan[] foregroundSpans = spannable.getSpans(0, spannable.length(), ForegroundColorSpan.class);
    for (ForegroundColorSpan span : foregroundSpans) {
      spannable.removeSpan(span);
    }

    // Highlight matches from search characters is Green color.
    if (searchString != null && !TextUtils.isEmpty(searchString)) {
      int index = spannable.toString().toLowerCase(Locale.US).indexOf(searchString);
      while (index != -1) {
        spannable.setSpan(getFCS(), index, index + searchString.length(), Spanned.SPAN_EXCLUSIVE_EXCLUSIVE);
        index = spannable.toString().indexOf(searchString, index + searchString.length());
      }
      cardBlankText2.setText(spannable, TextView.BufferType.SPANNABLE);
    }
  }

  @Override
  public void onBindViewHolder(@NonNull ViewHolder holder, int position) {
    final Card card = getCardAt(position);
    if (card != null) {
      holder.bindData(card, position);
    }
  }

  public Card getCardAt(int position) {
    return getItem(position);
  }
}

Solution

To rectify the highlighting issue, a crucial change must be made to the ListAdapter's setFilter method:

public void setFilter(List<Card> newSearchList, String adapSearchText) {
  if (newSearchList != null && !newSearchList.isEmpty()) {
    ArrayList<Card> tempList = new ArrayList<>();
    for (Card card: newSearchList) {
      card.setSearchString(adapSearchText.toLowerCase(Locale.US));
      tempList.add(card);
    }
    submitList(tempList);
  }
}

By adding a setSearchString method to the Card model and setting its value when filtering, we trigger a data change that prompts the onBindViewHolder() method to be called, subsequently updating the search text highlighting.

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