Recycler View with Header and Edit Text - filter

Question

I have a recyclerview with a header achieved by using two different element types. In my header there is an edit text which I want to use for filtering the nonheader elements of the list. Below is my current implementation, I have one concern and one problem with it.
My concern is that what I am doing in publishResults with the notifyItemRangeRemoved and notifyItemInserted is the wrong way to update the recycler view. I originally was doing notifyDatasetChanged but his would cause the header row to be refreshed too and the edit text to lose focus. What I really want is a way to refresh only the item rows and leave the header row untouched.
My current problem is that with the existing code if I scroll down too much the edit text looses focus. I want the edit text to keep focus even if I scroll to the bottom of the list.
The code used to use a ListView with setHeaderView and that worked somehow so there must be someway of achieving the goal just not sure what the trick with a recycler view is. Any help is much appreciated.
public class SideListAdapter extends RecyclerView.Adapter<RecyclerView.ViewHolder> implements Filterable {
private static final int TYPE_HEADER = 0;
private static final int TYPE_ITEM = 1;
private final List<String> data;
public List<String> filteredData;
private HeaderActionListener headerActionListener;
public SideListAdapter(Context context, ArrayList<String> data, HeaderActionListener headerActionListener) {
this.data = data;
filteredData = new ArrayList<>(data);
this.context = context;
this.headerActionListener = headerActionListener;
}
#Override
public Filter getFilter() {
return new TestFilter();
}
static class SideListItem extends RecyclerView.ViewHolder {
LinearLayout baseLayout;
public SideListItem(View itemView) {
super(itemView);
baseLayout = (LinearLayout) itemView.findViewById(R.id.settings_defaultcolor);
}
}
class SideListHeader extends SideListHeader {
EditText sort;
public SideListHeaderLoggedIn(View itemView) {
super(itemView);
sort = (EditText) itemView.findViewById(R.id.sort);
}
}
#Override
public RecyclerView.ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
if (viewType == TYPE_ITEM) {
View v = LayoutInflater.from(parent.getContext()).inflate(R.layout.list_item, parent, false);
return new SideListItem(v);
} else if (viewType == SideListHeader) {
View v = LayoutInflater.from(parent.getContext()).inflate(R.layout.header, parent, false);
return new SideListHeader(v);
}
throw new RuntimeException("there is no type that matches the type " + viewType + " + make sure your using types correctly");
}
public interface HeaderActionListener {
boolean onSortEditorAction(TextView arg0, int arg1, KeyEvent arg2);
}
#Override
public void onBindViewHolder(RecyclerView.ViewHolder holder, final int position) {
if (holder instanceof SideListHeader) {
final SideListHeader sideListHeader = (SideListHeader) holder;
sideListHeader.sort.setOnEditorActionListener(new TextView.OnEditorActionListener() {
#Override
public boolean onEditorAction(TextView v, int actionId, KeyEvent event) {
}
});
sideListHeader.sort.addTextChangedListener(new TextWatcher() {
#Override
public void beforeTextChanged(CharSequence charSequence, int i, int i2, int i3) {
}
#Override
public void onTextChanged(CharSequence charSequence, int i, int i2, int i3) {
}
#Override
public void afterTextChanged(Editable editable) {
String result = sideListHeader.sort.getText().toString().replaceAll(" ", "");
getFilter().filter(result);
}
});
}
if (holder instanceof SideListItem) {
// Inflate normal item //
}
}
// need to override this method
#Override
public int getItemViewType(int position) {
if (isPositionHeader(position)) {
return TYPE_HEADER;
}
return TYPE_ITEM;
}
private boolean isPositionHeader(int position) {
return position == 0;
}
//increasing getItemcount to 1. This will be the row of header.
#Override
public int getItemCount() {
return filteredData.size() + 1;
}
private class TestFilter extends Filter {
#Override
protected FilterResults performFiltering(CharSequence constraint) {
FilterResults results = new FilterResults();
String prefix = constraint.toString().toLowerCase();
if (prefix.isEmpty()) {
ArrayList<String> list = new ArrayList<>(data);
results.values = list;
results.count = list.size();
} else {
final ArrayList<String> list = new ArrayList<>(data);
final ArrayList<String> nlist = new ArrayList<>();
for (int i = 0 ; i < list.size(); i++) {
String item = list.get(i);
if (item.contains(prefix)) {
nlist.add(item);
}
}
results.values = nlist;
results.count = nlist.size();
}
return results;
}
#SuppressWarnings("unchecked")
#Override
protected void publishResults(CharSequence constraint, FilterResults results) {
notifyItemRangeRemoved(1, getItemCount()-1);
filteredData.clear();
filteredData.addAll((List<String>)results.values);
for(int i = 1; i < getItemCount() - 1; i++){
notifyItemInserted(i);
}
}
}
}

Answer 1

I'm not sure how correct this way is, but in my code I implemented it like that
private var headerList: List<HeaderItem> = listOf(HeaderItem("Title"))
private fun searchItem(items: List<Items>, query: String) {
items.filterIsInstance<MainItem>().filter { filteredItems ->
filteredItems.header.lowercase().contains(query.lowercase())
}.let { searchedItems ->
rvAdapter.submitList(headerList + searchedItems)
}
}
This way I was able to preserve header element when I did my search