How to Filter a RecyclerView with SearchView in Android

<?xml version="1.0" encoding="utf-8"?>
<android.support.constraint.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:background="@android:color/darker_gray"
    tools:context="tech.codingpoint.searchviewexample.MainActivity">

    <android.support.v7.widget.RecyclerView
        android:id="@+id/recycler_view"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:padding="4dp"
        android:scrollbars="vertical"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent" />

</android.support.constraint.ConstraintLayout>

<?xml version="1.0" encoding="utf-8"?>
<android.support.v7.widget.CardView xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:layout_marginBottom="4dp"
    app:cardCornerRadius="4dp">

    <RelativeLayout
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:layout_margin="4dp">

        <ImageView
            android:id="@+id/image_view"
            android:layout_width="50dp"
            android:layout_height="50dp"
            android:padding="2dp" />

        <TextView
            android:id="@+id/text_view1"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_alignParentTop="true"
            android:layout_toEndOf="@+id/image_view"
            android:text="Line 1"
            android:textColor="@android:color/black"
            android:textSize="20sp"
            android:textStyle="bold" />

        <TextView
            android:id="@+id/text_view2"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_below="@+id/text_view1"
            android:layout_marginStart="8dp"
            android:layout_toEndOf="@+id/image_view"
            android:text="Line 2"
            android:textSize="15sp" />

    </RelativeLayout>

</android.support.v7.widget.CardView>

<?xml version="1.0" encoding="utf-8"?>
<menu xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto">

    <item
        android:id="@+id/action_search"
        android:icon="@drawable/ic_search"
        android:title="Search"
        app:actionViewClass="android.support.v7.widget.SearchView"
        app:showAsAction="ifRoom|collapseActionView" />

</menu>

package tech.codingpoint.searchviewexample;

import android.support.annotation.NonNull;
import android.support.v7.widget.RecyclerView;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.Filter;
import android.widget.Filterable;
import android.widget.ImageView;
import android.widget.TextView;

import java.util.ArrayList;
import java.util.List;

public class ExampleAdapter extends RecyclerView.Adapter<ExampleAdapter.ExampleViewHolder> implements Filterable {
    private List<ExampleItem> exampleList;
    private List<ExampleItem> exampleListFull;

    class ExampleViewHolder extends RecyclerView.ViewHolder {
        ImageView imageView;
        TextView textView1;
        TextView textView2;

        ExampleViewHolder(View itemView) {
            super(itemView);
            imageView = itemView.findViewById(R.id.image_view);
            textView1 = itemView.findViewById(R.id.text_view1);
            textView2 = itemView.findViewById(R.id.text_view2);
        }
    }

    ExampleAdapter(List<ExampleItem> exampleList) {
        this.exampleList = exampleList;
        exampleListFull = new ArrayList<>(exampleList);
    }

    @NonNull
    @Override
    public ExampleViewHolder onCreateViewHolder(@NonNull ViewGroup parent, int viewType) {
        View v = LayoutInflater.from(parent.getContext()).inflate(R.layout.example_item,
                parent, false);
        return new ExampleViewHolder(v);
    }

    @Override
    public void onBindViewHolder(@NonNull ExampleViewHolder holder, int position) {
        ExampleItem currentItem = exampleList.get(position);

        holder.imageView.setImageResource(currentItem.getImageResource());
        holder.textView1.setText(currentItem.getText1());
        holder.textView2.setText(currentItem.getText2());
    }

    @Override
    public int getItemCount() {
        return exampleList.size();
    }

    @Override
    public Filter getFilter() {
        return exampleFilter;
    }

    private Filter exampleFilter = new Filter() {
        @Override
        protected FilterResults performFiltering(CharSequence constraint) {
            List<ExampleItem> filteredList = new ArrayList<>();

            if (constraint == null || constraint.length() == 0) {
                filteredList.addAll(exampleListFull);
            } else {
                String filterPattern = constraint.toString().toLowerCase().trim();

                for (ExampleItem item : exampleListFull) {
                    if (item.getText2().toLowerCase().contains(filterPattern)) {
                        filteredList.add(item);
                    }
                }
            }

            FilterResults results = new FilterResults();
            results.values = filteredList;

            return results;
        }

        @Override
        protected void publishResults(CharSequence constraint, FilterResults results) {
            exampleList.clear();
            exampleList.addAll((List) results.values);
            notifyDataSetChanged();
        }
    };
}

package tech.codingpoint.searchviewexample;

public class ExampleItem {
    private int imageResource;
    private String text1;
    private String text2;

    public ExampleItem(int imageResource, String text1, String text2) {
        this.imageResource = imageResource;
        this.text1 = text1;
        this.text2 = text2;
    }

    public int getImageResource() {
        return imageResource;
    }

    public String getText1() {
        return text1;
    }

    public String getText2() {
        return text2;
    }
}

package tech.codingpoint.searchviewexample;

import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.support.v7.widget.LinearLayoutManager;
import android.support.v7.widget.RecyclerView;
import android.support.v7.widget.SearchView;
import android.view.Menu;
import android.view.MenuInflater;
import android.view.MenuItem;
import android.view.inputmethod.EditorInfo;

import java.util.ArrayList;
import java.util.List;

public class MainActivity extends AppCompatActivity {
    private ExampleAdapter adapter;
    private List<ExampleItem> exampleList;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        fillExampleList();
        setUpRecyclerView();
    }

    private void fillExampleList() {
        exampleList = new ArrayList<>();
        exampleList.add(new ExampleItem(R.drawable.ic_android, "One", "Ten"));
        exampleList.add(new ExampleItem(R.drawable.ic_audio, "Two", "Eleven"));
        exampleList.add(new ExampleItem(R.drawable.ic_sun, "Three", "Twelve"));
        exampleList.add(new ExampleItem(R.drawable.ic_android, "Four", "Thirteen"));
        exampleList.add(new ExampleItem(R.drawable.ic_audio, "Five", "Fourteen"));
        exampleList.add(new ExampleItem(R.drawable.ic_sun, "Six", "Fifteen"));
        exampleList.add(new ExampleItem(R.drawable.ic_android, "Seven", "Sixteen"));
        exampleList.add(new ExampleItem(R.drawable.ic_audio, "Eight", "Seventeen"));
        exampleList.add(new ExampleItem(R.drawable.ic_sun, "Nine", "Eighteen"));
    }

    private void setUpRecyclerView() {
        RecyclerView recyclerView = findViewById(R.id.recycler_view);
        recyclerView.setHasFixedSize(true);
        RecyclerView.LayoutManager layoutManager = new LinearLayoutManager(this);
        adapter = new ExampleAdapter(exampleList);

        recyclerView.setLayoutManager(layoutManager);
        recyclerView.setAdapter(adapter);
    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        MenuInflater inflater = getMenuInflater();
        inflater.inflate(R.menu.example_menu, menu);

        MenuItem searchItem = menu.findItem(R.id.action_search);
        SearchView searchView = (SearchView) searchItem.getActionView();

        searchView.setImeOptions(EditorInfo.IME_ACTION_DONE);

        searchView.setOnQueryTextListener(new SearchView.OnQueryTextListener() {
            @Override
            public boolean onQueryTextSubmit(String query) {
                return false;
            }

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