How to Fix ForegroundColorSpan Search Text Highlighting Issues in RecyclerView with ListAdapter?

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

Highlighting search text in a RecyclerView can be challenging, especially when using ListAdapter. To address this issue, let's explore a potential solution to ensure that search text is correctly highlighted using a custom ListAdapter.

The problem arises when using submitList() to update the dataset in the ListAdapter. While it does correctly remove items from the list, it fails to trigger onBindViewHolder() for existing items because their data remains unchanged. This results in the highlighting mechanism not working as intended for these items.

Solution:

To resolve this issue, we need to modify the filtering logic to create new Card models with updated search strings instead of modifying the existing models in-place. Here's the revised code in MainActivity:

private void filter(String searchText) {
    ArrayList<card> searchList = new ArrayList();

    for (Card cardItem : mCards) {
        if (cardItem.getTodo().toLowerCase().contains(searchText.toLowerCase(Locale.US))) {                    
            Card updatedCard = new Card(cardItem.getTodo(), searchText);
            searchList.add(updatedCard);
        }
    }  
    if (!searchList.isEmpty()) {  
        adapter.setFilter(searchList);
}</card>

By creating new Card instances with updated search strings, we force the ListAdapter to trigger onBindViewHolder() for affected items, ensuring that the highlighting mechanism works correctly.

Updated ListAdapter:

In the ListAdapter, we remove the searchString property as it's no longer necessary. Instead, the search string information is included in the Card model. The bindData() method should now look like this:

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

    // Get any previous spans and remove them
    ForegroundColorSpan[] foregroundSpans = spannable.getSpans(0,spannable.length(), ForegroundColorSpan.class);

    // Highlight matches from search characters is Green color.
    if (card.getSearchText() != null) {
        int start = cardBlankText2.getText().toString().toLowerCase(Locale.US).indexOf(card.getSearchText().toLowerCase(Locale.US));
        int end = start + card.getSearchText().length();
        if (start != -1) {
            spannable.setSpan(getFCS(), start, end, Spanned.SPAN_EXCLUSIVE_EXCLUSIVE);
        }
        cardBlankText2.setText(spannable, TextView.BufferType.SPANNABLE);
    }    
}

With these changes, the search text highlighting feature should work as expected in the RecyclerView, ensuring that every occurrence of the search string is highlighted appropriately.

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