How to filter a RecyclerView with a SearchView

Question

I am trying to implement the SearchView from the support library  I want the user to be to use the SearchView to filter a List of movies in a RecyclerView   I have followed a few tutorials so far and I have added the SearchView to the ActionBar  but I am not really sure where to go from here  I have seen a few examples but none of them show results as you start typing   This is my MainActivity   public class MainActivity extends ActionBarActivity        RecyclerView mRecyclerView      RecyclerView LayoutManager mLayoutManager      RecyclerView Adapter mAdapter        Override     protected void onCreate Bundle savedInstanceState            super onCreate savedInstanceState           setContentView R layout activity recycler view            mRecyclerView    RecyclerView  findViewById R id recycler view           mRecyclerView setHasFixedSize true            mLayoutManager   new LinearLayoutManager this           mRecyclerView setLayoutManager mLayoutManager            mAdapter   new CardAdapter                  Override             public Filter getFilter                     return null                                   mRecyclerView setAdapter mAdapter               Override     public boolean onCreateOptionsMenu Menu menu               Inflate the menu  this adds items to the action bar if it is present          getMenuInflater   inflate R menu menu main  menu           SearchManager searchManager    SearchManager  getSystemService Context SEARCH SERVICE           SearchView searchView    SearchView  menu findItem R id menu search  getActionView            searchView setSearchableInfo searchManager getSearchableInfo getComponentName              return true              Override     public boolean onOptionsItemSelected MenuItem item               Handle action bar item clicks here  The action bar will            automatically handle clicks on the Home Up button  so long            as you specify a parent activity in AndroidManifest xml          int id   item getItemId               noinspection SimplifiableIfStatement         if  id    R id action settings                return true                     return super onOptionsItemSelected item             And this is my Adapter   public abstract class CardAdapter extends RecyclerView Adapter lt CardAdapter ViewHolder gt  implements Filterable        List lt Movie gt  mItems       public CardAdapter             super            mItems   new ArrayList lt Movie gt             Movie movie   new Movie            movie setName  Spiderman            movie setRating  92            mItems add movie            movie   new Movie            movie setName  Doom 3            movie setRating  91            mItems add movie            movie   new Movie            movie setName  Transformers            movie setRating  88            mItems add movie            movie   new Movie            movie setName  Transformers 2            movie setRating  87            mItems add movie            movie   new Movie            movie setName  Transformers 3            movie setRating  86            mItems add movie            movie   new Movie            movie setName  Noah            movie setRating  86            mItems add movie            movie   new Movie            movie setName  Ironman            movie setRating  86            mItems add movie            movie   new Movie            movie setName  Ironman 2            movie setRating  86            mItems add movie            movie   new Movie            movie setName  Ironman 3            movie setRating  86            mItems add movie               Override     public ViewHolder onCreateViewHolder ViewGroup viewGroup  int i            View v   LayoutInflater from viewGroup getContext    inflate R layout recycler view card item  viewGroup  false           return new ViewHolder v               Override     public void onBindViewHolder ViewHolder viewHolder  int i            Movie movie   mItems get i           viewHolder tvMovie setText movie getName             viewHolder tvMovieRating setText movie getRating                 Override     public int getItemCount             return mItems size               class ViewHolder extends RecyclerView ViewHolder           public TextView tvMovie          public TextView tvMovieRating           public ViewHolder View itemView                super itemView               tvMovie    TextView itemView findViewById R id movieName               tvMovieRating    TextView itemView findViewById R id movieRating

User · Answer

Add an interface in your adapter   public interface SelectedUser       void selectedUser UserModel userModel        implement the interface in your mainactivity and override the method       Override     public void selectedUser UserModel userModel         startActivity new Intent MainActivity this  SelectedUserActivity class  putExtra  data  userModel           Full tutorial and source code  Recyclerview with searchview and onclicklistener

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Following  Shruthi Kamoji in a cleaner way  we can just use a filterable  its meant for that   public abstract class GenericRecycleAdapter lt E gt  extends RecyclerView Adapter implements Filterable       protected List lt E gt  list      protected List lt E gt  originalList      protected Context context       public GenericRecycleAdapter Context context      List lt E gt  list                this originalList   list          this list   list          this context   context                       Override     public Filter getFilter             return new Filter                  SuppressWarnings  unchecked                Override             protected void publishResults CharSequence constraint  FilterResults results                    list    List lt E gt   results values                  notifyDataSetChanged                                Override             protected FilterResults performFiltering CharSequence constraint                    List lt E gt  filteredResults   null                  if  constraint length      0                        filteredResults   originalList                    else                       filteredResults   getFilteredResults constraint toString   toLowerCase                                        FilterResults results   new FilterResults                    results values   filteredResults                   return results                                      protected List lt E gt  getFilteredResults String constraint            List lt E gt  results   new ArrayList lt  gt              for  E item   originalList                if  item getName   toLowerCase   contains constraint                     results add item                                   return results             The E here is a Generic Type  you can extend it using your class   public class customerAdapter extends GenericRecycleAdapter lt CustomerModel gt    Or just change the E to the type you want   lt CustomerModel gt  for example   Then from searchView  the widget you can put on menu xml    searchView setOnQueryTextListener new SearchView OnQueryTextListener          Override     public boolean onQueryTextSubmit String text            return false              Override     public boolean onQueryTextChange String text            yourAdapter getFilter   filter text           return true

User · Answer

This is my take on expanding  klimat answer to not losing filtering animation   public void filter String query       int completeListIndex   0      int filteredListIndex   0      while  completeListIndex  lt  completeList size             Movie item   completeList get completeListIndex           if item getName   toLowerCase   contains query                if filteredListIndex  lt  filteredList size                      Movie filter   filteredList get filteredListIndex                   if   item getName   equals filter getName                           filteredList add filteredListIndex  item                       notifyItemInserted filteredListIndex                                  else                  filteredList add filteredListIndex  item                   notifyItemInserted filteredListIndex                             filteredListIndex                      else if filteredListIndex  lt  filteredList size                 Movie filter   filteredList get filteredListIndex               if  item getName   equals filter getName                       filteredList remove filteredListIndex                   notifyItemRemoved filteredListIndex                                   completeListIndex              Basically what it does is looking through a complete list and adding removing items to a filtered list one by one

User · Answer

With Android Architecture Components through the use of LiveData this can be easily implemented with any type of Adapter  You simply have to do the following steps   1  Setup your data to return from the Room Database as LiveData as in the example below    Dao public interface CustomDAO    Query  SELECT   FROM words table WHERE column LIKE  searchquery       public LiveData lt List lt Word gt  gt  searchFor String searchquery       2  Create a ViewModel object to update your data live through a method that will connect your DAO and your UI  public class CustomViewModel extends AndroidViewModel        private final AppDatabase mAppDatabase       public WordListViewModel  NonNull Application application            super application           this mAppDatabase   AppDatabase getInstance application getApplicationContext                public LiveData lt List lt Word gt  gt  searchQuery String query            return mAppDatabase mWordDAO   searchFor query              3  Call your data from the ViewModel on the fly by passing in the query through onQueryTextListener as below   Inside onCreateOptionsMenu set your listener as follows  searchView setOnQueryTextListener onQueryTextListener     Setup your query listener somewhere in your SearchActivity class as follows  private android support v7 widget SearchView OnQueryTextListener onQueryTextListener               new android support v7 widget SearchView OnQueryTextListener                      Override                 public boolean onQueryTextSubmit String query                        getResults query                       return true                                      Override                 public boolean onQueryTextChange String newText                        getResults newText                       return true                                     private void getResults String newText                        String queryText         newText                            mCustomViewModel searchQuery queryText  observe                              SearchResultsActivity this  new Observer lt List lt Word gt  gt                                       Override                                 public void onChanged  Nullable List lt Word gt  words                                        if  words    null  return                                      searchAdapter submitList words                                                                                                        Note  Steps  1   and  2   are standard AAC ViewModel and DAO implementation  the only real  magic  going on here is in the OnQueryTextListener which will update the results of your list dynamically as the query text changes   If you need more clarification on the matter please don t hesitate to ask  I hope this helped

User · Answer

In Adapter   public void setFilter List lt Channel gt  newList           mChannels   new ArrayList lt  gt             mChannels addAll newList           notifyDataSetChanged            In Activity   searchView setOnQueryTextListener new SearchView OnQueryTextListener                  Override             public boolean onQueryTextSubmit String query                    return false                              Override             public boolean onQueryTextChange String newText                    newText   newText toLowerCase                    ArrayList lt Channel gt  newList   new ArrayList lt  gt                     for  Channel channel  channels                       String channelName   channel getmChannelName   toLowerCase                        if  channelName contains newText                            newList add channel                                                           mAdapter setFilter newList                   return true

User · Answer

I have solved the same problem using the link with some modifications in it  Search filter on RecyclerView with Cards  Is it even possible   hope this helps    Here is my adapter class  public class ContactListRecyclerAdapter extends RecyclerView Adapter lt ContactListRecyclerAdapter ContactViewHolder gt  implements Filterable    Context mContext  ArrayList lt Contact gt  customerList  ArrayList lt Contact gt  parentCustomerList    public ContactListRecyclerAdapter Context context ArrayList lt Contact gt  customerList        this mContext context      this customerList customerList      if customerList  null      parentCustomerList new ArrayList lt  gt  customerList            other overrided methods   Override public Filter getFilter         return new FilterCustomerSearch this parentCustomerList           Filter class  import android widget Filter  import java util ArrayList    public class FilterCustomerSearch extends Filter   private final ContactListRecyclerAdapter mAdapter  ArrayList lt Contact gt  contactList  ArrayList lt Contact gt  filteredList   public FilterCustomerSearch ContactListRecyclerAdapter mAdapter ArrayList lt Contact gt  contactList        this mAdapter   mAdapter      this contactList contactList      filteredList new ArrayList lt  gt         Override protected FilterResults performFiltering CharSequence constraint        filteredList clear        final FilterResults results   new FilterResults         if  constraint length      0            filteredList addAll contactList         else           final String filterPattern   constraint toString   toLowerCase   trim             for  final Contact contact   contactList                if  contact customerName contains constraint                     filteredList add contact                             else if  contact emailId contains constraint                                 filteredList add contact                              else if contact phoneNumber contains constraint                   filteredList add contact                       results values   filteredList      results count   filteredList size        return results      Override protected void publishResults CharSequence constraint  FilterResults results        mAdapter customerList clear        mAdapter customerList addAll  ArrayList lt Contact gt   results values       mAdapter notifyDataSetChanged             Activity class  public class HomeCrossFadeActivity extends AppCompatActivity implements View OnClickListener OnFragmentInteractionListener OnTaskCompletedListner   Fragment fragment   protected void onCreate Bundle savedInstanceState        super onCreate savedInstanceState       setContentView R layout activity homecrossfadeslidingpane2  CardView mCard     setContentView R layout your main xml         other overrided methods    Override    public boolean onCreateOptionsMenu Menu menu           Inflate the menu  this adds items to the action bar if it is present       MenuInflater inflater   getMenuInflater           Inflate menu to add items to action bar if it is present      inflater inflate R menu menu customer view and search  menu          Associate searchable configuration with the SearchView     SearchManager searchManager                SearchManager  getSystemService Context SEARCH SERVICE       SearchView searchView                SearchView  menu findItem R id menu search  getActionView        searchView setQueryHint  Search Customer        searchView setSearchableInfo              searchManager getSearchableInfo getComponentName           searchView setOnQueryTextListener new SearchView OnQueryTextListener              Override         public boolean onQueryTextSubmit String query                return false                      Override         public boolean onQueryTextChange String newText                if fragment instanceof CustomerDetailsViewWithModifyAndSearch                    CustomerDetailsViewWithModifyAndSearch fragment  adapter getFilter   filter newText               return false                           return true        In OnQueryTextChangeListener   method use your adapter  I have casted it to fragment as my adpter is in fragment  You can use the adapter directly if its in your activity class

User · Answer

All you need to do is to add filter method in RecyclerView Adapter   public void filter String text        items clear        if text isEmpty             items addAll itemsCopy         else          text   text toLowerCase            for PhoneBookItem item  itemsCopy               if item name toLowerCase   contains text     item phone toLowerCase   contains text                    items add item                                     notifyDataSetChanged        itemsCopy is initialized in adapter s constructor like itemsCopy addAll items     If you do so  just call filter from OnQueryTextListener   searchView setOnQueryTextListener new SearchView OnQueryTextListener          Override     public boolean onQueryTextSubmit String query            adapter filter query           return true              Override     public boolean onQueryTextChange String newText            adapter filter newText           return true              It s an example from filtering my phonebook by name and phone number

User · Answer

simply create two list in adapter one orignal and one temp and implements Filterable         Override     public Filter getFilter             return new Filter                  Override             protected FilterResults performFiltering CharSequence constraint                    final FilterResults oReturn   new FilterResults                    final ArrayList lt T gt  results   new ArrayList lt  gt                     if  origList    null                      origList   new ArrayList lt  gt  itemList                   if  constraint    null  amp  amp  constraint length    gt  0                        if  origList    null  amp  amp  origList size    gt  0                            for  final T cd   origList                                if  cd getAttributeToSearch   toLowerCase                                        contains constraint toString   toLowerCase                                     results add cd                                                                       oReturn values   results                      oReturn count   results size     newly Aded by ZA                   else                       oReturn values   origList                      oReturn count   origList size     newly added by ZA                                   return oReturn                              SuppressWarnings  unchecked                Override             protected void publishResults final CharSequence constraint                                            FilterResults results                    itemList   new ArrayList lt  gt   ArrayList lt T gt   results values                      FIXME  8 16 2017 implement Comparable with sort below                    Collections sort itemList                   notifyDataSetChanged                                     where  public GenericBaseAdapter Context mContext  List lt T gt  itemList            this mContext   mContext          this itemList   itemList          this origList   itemList

User · Answer

I recommend modify the solution of  Xaver Kapeller with 2 things below to avoid a problem after you cleared the searched text  the filter didn t work anymore  due to the list back of adapter has smaller size than filter list and the IndexOutOfBoundsException happened  So the code need to modify as below  public void addItem int position  ExampleModel model        if position  gt   mModel size              mModel add model           notifyItemInserted mModel size  -1         else           mModels add position  model           notifyItemInserted position             And modify also in moveItem functionality  public void moveItem int fromPosition  int toPosition        final ExampleModel model   mModels remove fromPosition       if toPosition  gt   mModels size              mModels add model           notifyItemMoved fromPosition  mModels size  -1         else           mModels add toPosition  model           notifyItemMoved fromPosition  toPosition              Hope that It could help you

User · Answer

Introduction  Since it is not really clear from your question what exactly you are having trouble with  I wrote up this quick walkthrough about how to implement this feature  if you still have questions feel free to ask   I have a working example of everything I am talking about here in this GitHub Repository  If you want to know more about the example project visit the project homepage   In any case the result should looks something like this     If you first want to play around with the demo app you can install it from the Play Store     Anyway lets get started     Setting up the SearchView  In the folder res menu create a new file called main menu xml  In it add an item and set the actionViewClass to android support v7 widget SearchView  Since you are using the support library you have to use the namespace of the support library to set the actionViewClass attribute  Your xml file should look something like this    lt menu xmlns android  http   schemas android com apk res android        xmlns app  http   schemas android com apk res-auto  gt        lt item android id    id action search            android title   string action search            app actionViewClass  android support v7 widget SearchView            app showAsAction  always   gt    lt  menu gt    In your Fragment or Activity you have to inflate this menu xml like usual  then you can look for the MenuItem which contains the SearchView and implement the OnQueryTextListener which we are going to use to listen for changes to the text entered into the SearchView    Override public boolean onCreateOptionsMenu Menu menu        getMenuInflater   inflate R menu menu main  menu        final MenuItem searchItem   menu findItem R id action search       final SearchView searchView    SearchView  searchItem getActionView        searchView setOnQueryTextListener this        return true      Override public boolean onQueryTextChange String query           Here is where we are going to implement the filter logic     return false      Override public boolean onQueryTextSubmit String query        return false      And now the SearchView is ready to be used  We will implement the filter logic later on in onQueryTextChange   once we are finished implementing the Adapter     Setting up the Adapter  First and foremost this is the model class I am going to use for this example    public class ExampleModel        private final long mId      private final String mText       public ExampleModel long id  String text            mId   id          mText   text             public long getId             return mId             public String getText             return mText            It s just your basic model which will display a text in the RecyclerView  This is the layout I am going to use to display the text     lt  xml version  1 0  encoding  utf-8   gt   lt layout xmlns android  http   schemas android com apk res android  gt        lt data gt            lt variable             name  model              type  com github wrdlbrnft searchablerecyclerviewdemo ui models ExampleModel   gt        lt  data gt        lt FrameLayout         android layout width  match parent          android layout height  wrap content          android background   attr selectableItemBackground          android clickable  true  gt            lt TextView             android layout width  match parent              android layout height  wrap content              android padding  8dp              android text    model text    gt        lt  FrameLayout gt    lt  layout gt    As you can see I use Data Binding  If you have never worked with data binding before don t be discouraged  It s very simple and powerful  however I can t explain how it works in the scope of this answer   This is the ViewHolder for the ExampleModel class   public class ExampleViewHolder extends RecyclerView ViewHolder        private final ItemExampleBinding mBinding       public ExampleViewHolder ItemExampleBinding binding            super binding getRoot             mBinding   binding             public void bind ExampleModel item            mBinding setModel item             Again nothing special  It just uses data binding to bind the model class to this layout as we have defined in the layout xml above    Now we can finally come to the really interesting part  Writing the Adapter  I am going to skip over the basic implementation of the Adapter and am instead going to concentrate on the parts which are relevant for this answer   But first there is one thing we have to talk about  The SortedList class     SortedList  The SortedList is a completely amazing tool which is part of the RecyclerView library  It takes care of notifying the Adapter about changes to the data set and does so it a very efficient way  The only thing it requires you to do is specify an order of the elements  You need to do that by implementing a compare   method which compares two elements in the SortedList just like a Comparator  But instead of sorting a List it is used to sort the items in the RecyclerView    The SortedList interacts with the Adapter through a Callback class which you have to implement   private final SortedList Callback lt ExampleModel gt  mCallback   new SortedList Callback lt ExampleModel gt            Override     public void onInserted int position  int count             mAdapter notifyItemRangeInserted position  count               Override     public void onRemoved int position  int count            mAdapter notifyItemRangeRemoved position  count               Override     public void onMoved int fromPosition  int toPosition            mAdapter notifyItemMoved fromPosition  toPosition               Override     public void onChanged int position  int count            mAdapter notifyItemRangeChanged position  count               Override     public int compare ExampleModel a  ExampleModel b            return mComparator compare a  b               Override     public boolean areContentsTheSame ExampleModel oldItem  ExampleModel newItem            return oldItem equals newItem               Override     public boolean areItemsTheSame ExampleModel item1  ExampleModel item2            return item1 getId      item2 getId              In the methods at the top of the callback like onMoved  onInserted  etc  you have to call the equivalent notify method of your Adapter  The three methods at the bottom compare  areContentsTheSame and areItemsTheSame you have to implement according to what kind of objects you want to display and in what order these objects should appear on the screen   Let s go through these methods one by one    Override public int compare ExampleModel a  ExampleModel b        return mComparator compare a  b       This is the compare   method I talked about earlier  In this example I am just passing the call to a Comparator which compares the two models  If you want the items to appear in alphabetical order on the screen  This comparator might look like this   private static final Comparator lt ExampleModel gt  ALPHABETICAL COMPARATOR   new Comparator lt ExampleModel gt           Override     public int compare ExampleModel a  ExampleModel b            return a getText   compareTo b getText                Now let s take a look at the next method    Override public boolean areContentsTheSame ExampleModel oldItem  ExampleModel newItem        return oldItem equals newItem       The purpose of this method is to determine if the content of a model has changed  The SortedList uses this to determine if a change event needs to be invoked - in other words if the RecyclerView should crossfade the old and new version  If you model classes have a correct equals   and hashCode   implementation you can usually just implement it like above  If we add an equals   and hashCode   implementation to the ExampleModel class it should look something like this   public class ExampleModel implements SortedListAdapter ViewModel        private final long mId      private final String mText       public ExampleModel long id  String text            mId   id          mText   text             public long getId             return mId             public String getText             return mText              Override     public boolean equals Object o            if  this    o  return true          if  o    null    getClass      o getClass    return false           ExampleModel model    ExampleModel  o           if  mId    model mId  return false          return mText    null   mText equals model mText    model mText    null               Override     public int hashCode             int result    int   mId    mId  gt  gt  gt  32            result   31   result    mText    null   mText hashCode     0           return result            Quick side note  Most IDE s like Android Studio  IntelliJ and Eclipse have functionality to generate equals   and hashCode   implementations for you at the press of a button  So you don t have to implement them yourself  Look up on the internet how it works in your IDE   Now let s take a look at the last method    Override public boolean areItemsTheSame ExampleModel item1  ExampleModel item2        return item1 getId      item2 getId        The SortedList uses this method to check if two items refer to the same thing  In simplest terms  without explaining how the SortedList works  this is used to determine if an object is already contained in the List and if either an add  move or change animation needs to be played  If your models have an id you would usually compare just the id in this method  If they don t you need to figure out some other way to check this  but however you end up implementing this depends on your specific app  Usually it is the simplest option to give all models an id - that could for example be the primary key field if you are querying the data from a database   With the SortedList Callback correctly implemented we can create an instance of the SortedList   final SortedList lt ExampleModel gt  list   new SortedList lt  gt  ExampleModel class  mCallback     As the first parameter in the constructor of the SortedList you need to pass the class of your models  The other parameter is just the SortedList Callback we defined above   Now let s get down to business  If we implement the Adapter with a SortedList it should look something like this   public class ExampleAdapter extends RecyclerView Adapter lt ExampleViewHolder gt         private final SortedList lt ExampleModel gt  mSortedList   new SortedList lt  gt  ExampleModel class  new SortedList Callback lt ExampleModel gt               Override         public int compare ExampleModel a  ExampleModel b                return mComparator compare a  b                       Override         public void onInserted int position  int count                notifyItemRangeInserted position  count                       Override         public void onRemoved int position  int count                notifyItemRangeRemoved position  count                       Override         public void onMoved int fromPosition  int toPosition                notifyItemMoved fromPosition  toPosition                       Override         public void onChanged int position  int count                notifyItemRangeChanged position  count                       Override         public boolean areContentsTheSame ExampleModel oldItem  ExampleModel newItem                return oldItem equals newItem                       Override         public boolean areItemsTheSame ExampleModel item1  ExampleModel item2                return item1 getId      item2 getId                           private final LayoutInflater mInflater      private final Comparator lt ExampleModel gt  mComparator       public ExampleAdapter Context context  Comparator lt ExampleModel gt  comparator            mInflater   LayoutInflater from context           mComparator   comparator              Override     public ExampleViewHolder onCreateViewHolder ViewGroup parent  int viewType            final ItemExampleBinding binding   ItemExampleBinding inflate inflater  parent  false           return new ExampleViewHolder binding               Override     public void onBindViewHolder ExampleViewHolder holder  int position            final ExampleModel model   mSortedList get position           holder bind model               Override     public int getItemCount             return mSortedList size              The Comparator used to sort the item is passed in through the constructor so we can use the same Adapter even if the items are supposed to be displayed in a different order   Now we are almost done  But we first need a way to add or remove items to the Adapter  For this purpose we can add methods to the Adapter which allow us to add and remove items to the SortedList   public void add ExampleModel model        mSortedList add model      public void remove ExampleModel model        mSortedList remove model      public void add List lt ExampleModel gt  models        mSortedList addAll models      public void remove List lt ExampleModel gt  models        mSortedList beginBatchedUpdates        for  ExampleModel model   models            mSortedList remove model             mSortedList endBatchedUpdates        We don t need to call any notify methods here because the SortedList already does this for through the SortedList Callback  Aside from that the implementation of these methods is pretty straight forward with one exception  the remove method which removes a List of models  Since the SortedList has only one remove method which can remove a single object we need to loop over the list and remove the models one by one  Calling beginBatchedUpdates   at the beginning batches all the changes we are going to make to the SortedList together and improves performance  When we call endBatchedUpdates   the RecyclerView is notified about all the changes at once    Additionally what you have to understand is that if you add an object to the SortedList and it is already in the SortedList it won t be added again  Instead the SortedList uses the areContentsTheSame   method to figure out if the object has changed - and if it has the item in the RecyclerView will be updated   Anyway  what I usually prefer is one method which allows me to replace all items in the RecyclerView at once  Remove everything which is not in the List and add all items which are missing from the SortedList   public void replaceAll List lt ExampleModel gt  models        mSortedList beginBatchedUpdates        for  int i   mSortedList size   - 1  i  gt   0  i--            final ExampleModel model   mSortedList get i           if   models contains model                 mSortedList remove model                       mSortedList addAll models       mSortedList endBatchedUpdates        This method again batches all updates together to increase performance  The first loop is in reverse since removing an item at the start would mess up the indexes of all items that come up after it and this can lead in some instances to problems like data inconsistencies  After that we just add the List to the SortedList using addAll   to add all items which are not already in the SortedList and - just like I described above - update all items that are already in the SortedList but have changed   And with that the Adapter is complete  The whole thing should look something like this   public class ExampleAdapter extends RecyclerView Adapter lt ExampleViewHolder gt         private final SortedList lt ExampleModel gt  mSortedList   new SortedList lt  gt  ExampleModel class  new SortedList Callback lt ExampleModel gt               Override         public int compare ExampleModel a  ExampleModel b                return mComparator compare a  b                       Override         public void onInserted int position  int count                notifyItemRangeInserted position  count                       Override         public void onRemoved int position  int count                notifyItemRangeRemoved position  count                       Override         public void onMoved int fromPosition  int toPosition                notifyItemMoved fromPosition  toPosition                       Override         public void onChanged int position  int count                notifyItemRangeChanged position  count                       Override         public boolean areContentsTheSame ExampleModel oldItem  ExampleModel newItem                return oldItem equals newItem                       Override         public boolean areItemsTheSame ExampleModel item1  ExampleModel item2                return item1    item2                         private final Comparator lt ExampleModel gt  mComparator      private final LayoutInflater mInflater       public ExampleAdapter Context context  Comparator lt ExampleModel gt  comparator            mInflater   LayoutInflater from context           mComparator   comparator              Override     public ExampleViewHolder onCreateViewHolder ViewGroup parent  int viewType            final ItemExampleBinding binding   ItemExampleBinding inflate mInflater  parent  false           return new ExampleViewHolder binding               Override     public void onBindViewHolder ExampleViewHolder holder  int position            final ExampleModel model   mSortedList get position           holder bind model              public void add ExampleModel model            mSortedList add model              public void remove ExampleModel model            mSortedList remove model              public void add List lt ExampleModel gt  models            mSortedList addAll models              public void remove List lt ExampleModel gt  models            mSortedList beginBatchedUpdates            for  ExampleModel model   models                mSortedList remove model                     mSortedList endBatchedUpdates               public void replaceAll List lt ExampleModel gt  models            mSortedList beginBatchedUpdates            for  int i   mSortedList size   - 1  i  gt   0  i--                final ExampleModel model   mSortedList get i               if   models contains model                     mSortedList remove model                                   mSortedList addAll models           mSortedList endBatchedUpdates                Override     public int getItemCount             return mSortedList size              The only thing missing now is to implement the filtering     Implementing the filter logic  To implement the filter logic we first have to define a List of all possible models  For this example I create a List of ExampleModel instances from an array of movies   private static final String   MOVIES   new String                    private static final Comparator lt ExampleModel gt  ALPHABETICAL COMPARATOR   new Comparator lt ExampleModel gt           Override     public int compare ExampleModel a  ExampleModel b            return a getText   compareTo b getText               private ExampleAdapter mAdapter  private List lt ExampleModel gt  mModels  private RecyclerView mRecyclerView        Override protected void onCreate Bundle savedInstanceState        super onCreate savedInstanceState       mBinding   DataBindingUtil setContentView this  R layout activity main        mAdapter   new ExampleAdapter this  ALPHABETICAL COMPARATOR        mBinding recyclerView setLayoutManager new LinearLayoutManager this        mBinding recyclerView setAdapter mAdapter        mModels   new ArrayList lt  gt         for  String movie   MOVIES            mModels add new ExampleModel movie              mAdapter add mModels       Nothing special going on here  we just instantiate the Adapter and set it to the RecyclerView  After that we create a List of models from the movie names in the MOVIES array  Then we add all the models to the SortedList   Now we can go back to onQueryTextChange   which we defined earlier and start implementing the filter logic    Override public boolean onQueryTextChange String query        final List lt ExampleModel gt  filteredModelList   filter mModels  query       mAdapter replaceAll filteredModelList       mBinding recyclerView scrollToPosition 0       return true      This is again pretty straight forward  We call the method filter   and pass in the List of ExampleModels as well as the query string  We then call replaceAll   on the Adapter and pass in the filtered List returned by filter    We also have to call scrollToPosition 0  on the RecyclerView to ensure that the user can always see all items when searching for something  Otherwise the RecyclerView might stay in a scrolled down position while filtering and subsequently hide a few items  Scrolling to the top ensures a better user experience while searching   The only thing left to do now is to implement filter   itself   private static List lt ExampleModel gt  filter List lt ExampleModel gt  models  String query        final String lowerCaseQuery   query toLowerCase         final List lt ExampleModel gt  filteredModelList   new ArrayList lt  gt         for  ExampleModel model   models            final String text   model getText   toLowerCase            if  text contains lowerCaseQuery                 filteredModelList add model                       return filteredModelList      The first thing we do here is call toLowerCase   on the query string  We don t want our search function to be case sensitive and by calling toLowerCase   on all strings we compare we can ensure that we return the same results regardless of case  It then just iterates through all the models in the List we passed into it and checks if the query string is contained in the text of the model  If it is then the model is added to the filtered List   And that s it  The above code will run on API level 7 and above and starting with API level 11 you get item animations for free    I realize that this is a very detailed description which probably makes this whole thing seem more complicated than it really is  but there is a way we can generalize this whole problem and make implementing an Adapter based on a SortedList much simpler     Generalizing the problem and simplifying the Adapter  In this section I am not going to go into much detail - partly because I am running up against the character limit for answers on Stack Overflow but also because most of it already explained above - but to summarize the changes  We can implemented a base Adapter class which already takes care of dealing with the SortedList as well as binding models to ViewHolder instances and provides a convenient way to implement an Adapter based on a SortedList  For that we have to do two things    We need to create a ViewModel interface which all model classes have to implement We need to create a ViewHolder subclass which defines a bind   method the Adapter can use to bind models automatically    This allows us to just focus on the content which is supposed to be displayed in the RecyclerView by just implementing the models and there corresponding ViewHolder implementations  Using this base class we don t have to worry about the intricate details of the Adapter and its SortedList    SortedListAdapter  Because of the character limit for answers on StackOverflow I can t go through each step of implementing this base class or even add the full source code here  but you can find the full source code of this base class - I called it SortedListAdapter - in this GitHub Gist   To make your life simple I have published a library on jCenter which contains the SortedListAdapter  If you want to use it then all you need to do is add this dependency to your app s build gradle file   compile  com github wrdlbrnft sorted-list-adapter 0 2 0 1    You can find more information about this library on the library homepage    Using the SortedListAdapter  To use the SortedListAdapter we have to make two changes    Change the ViewHolder so that it extends SortedListAdapter ViewHolder  The type parameter should be the model which should be bound to this ViewHolder - in this case ExampleModel  You have to bind data to your models in performBind   instead of bind     public class ExampleViewHolder extends SortedListAdapter ViewHolder lt ExampleModel gt         private final ItemExampleBinding mBinding       public ExampleViewHolder ItemExampleBinding binding            super binding getRoot             mBinding   binding              Override     protected void performBind ExampleModel item            mBinding setModel item            Make sure that all your models implement the ViewModel interface   public class ExampleModel implements SortedListAdapter ViewModel                After that we just have to update the ExampleAdapter to extend SortedListAdapter and remove everything we don t need anymore  The type parameter should be the type of model you are working with - in this case ExampleModel  But if you are working with different types of models then set the type parameter to ViewModel   public class ExampleAdapter extends SortedListAdapter lt ExampleModel gt         public ExampleAdapter Context context  Comparator lt ExampleModel gt  comparator            super context  ExampleModel class  comparator               Override     protected ViewHolder lt   extends ExampleModel gt  onCreateViewHolder LayoutInflater inflater  ViewGroup parent  int viewType            final ItemExampleBinding binding   ItemExampleBinding inflate inflater  parent  false           return new ExampleViewHolder binding               Override     protected boolean areItemsTheSame ExampleModel item1  ExampleModel item2            return item1 getId      item2 getId                Override     protected boolean areItemContentsTheSame ExampleModel oldItem  ExampleModel newItem            return oldItem equals newItem             After that we are done  However one last thing to mention  The SortedListAdapter does not have the same add    remove   or replaceAll   methods our original ExampleAdapter had  It uses a separate Editor object to modify the items in the list which can be accessed through the edit   method  So if you want to remove or add items you have to call edit   then add and remove the items on this Editor instance and once you are done  call commit   on it to apply the changes to the SortedList   mAdapter edit            remove modelToRemove           add listOfModelsToAdd           commit      All changes you make this way are batched together to increase performance  The replaceAll   method we implemented in the chapters above is also present on this Editor object   mAdapter edit            replaceAll mModels           commit      If you forget to call commit   then none of your changes will be applied

User · Answer

I don t know why everyone is using 2 copies of the same list to solve this  This uses too much RAM    Why not just hide the elements that are not found  and simply store their index in a Set to be able to restore them later  That s much less RAM especially if your objects are quite large  public class MyRecyclerViewAdapter extends RecyclerView Adapter lt MyRecyclerViewAdapter SampleViewHolders gt       private List lt MyObject gt  myObjectsList    holds the items of type MyObject     private Set lt Integer gt  foundObjects    holds the indices of the found items      public MyRecyclerViewAdapter Context context  List lt MyObject gt  myObjectsList                this myObjectsList   myObjectsList          this foundObjects   new HashSet lt  gt               first  add all indices to the indices set         for int i   0  i  lt  this myObjectsList size    i                          this foundObjects add i                         NonNull      Override     public SampleViewHolders onCreateViewHolder  NonNull ViewGroup parent  int viewType            View layoutView   LayoutInflater from parent getContext    inflate                  R layout my layout for staggered grid  null           MyRecyclerViewAdapter SampleViewHolders rcv   new MyRecyclerViewAdapter SampleViewHolders layoutView           return rcv              Override     public void onBindViewHolder  NonNull SampleViewHolders holder  int position                  look for object in O 1  in the indices set         if  foundObjects contains position                           object not found   gt  hide it              holder hideLayout                return                    else                         object found   gt  show it              holder showLayout                         holder imgImageView setImageResource                holder nameTextView setText                  Override     public int getItemCount             return myObjectsList size               public void findObject String text                  look for  quot text quot  in the objects list         for int i   0  i  lt  myObjectsList size    i                            if it s empty text  we want all objects  so just add it to the set              if text length      0                                foundObjects add i                             else                                 otherwise check if it meets your search criteria and add it or remove it accordingly                 if  myObjectsList get i  getName   toLowerCase   contains text toLowerCase                                           foundObjects add i                                     else                                       foundObjects remove i                                                     notifyDataSetChanged               public class SampleViewHolders extends RecyclerView ViewHolder implements View OnClickListener               public ImageView imgImageView          public TextView nameTextView           private final CardView layout          private final CardView LayoutParams hiddenLayoutParams          private final CardView LayoutParams shownLayoutParams                    public SampleViewHolders View itemView                        super itemView               itemView setOnClickListener this               imgImageView    ImageView  itemView findViewById R id some image view               nameTextView    TextView  itemView findViewById R id display name textview                layout   itemView findViewById R id card view     card view is the id of my androidx cardview widget CardView in my xml layout               prepare hidden layout params with height   0  and visible layout params for later - see hideLayout   and showLayout               hiddenLayoutParams   new CardView LayoutParams ViewGroup LayoutParams MATCH PARENT                      ViewGroup LayoutParams WRAP CONTENT               hiddenLayoutParams height   0              shownLayoutParams   new CardView LayoutParams ViewGroup LayoutParams MATCH PARENT                      ViewGroup LayoutParams WRAP CONTENT                       Override         public void onClick View view                          implement                       private void hideLayout                   hide the layout             layout setLayoutParams hiddenLayoutParams                      private void showLayout                   show the layout             layout setLayoutParams shownLayoutParams                      And I simply have an EditText as my search box  cardsSearchTextView addTextChangedListener new TextWatcher                  Override             public void beforeTextChanged CharSequence charSequence  int i  int i1  int i2                                 Override             public void onTextChanged CharSequence charSequence  int i  int i1  int i2                                 Override             public void afterTextChanged Editable editable                    myViewAdapter findObject editable toString   toLowerCase                                Result

[android] How to filter a RecyclerView with a SearchView

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