MainActivity.java

public class MainActivity extends AppCompatActivity
        implements NavigationView.OnNavigationItemSelectedListener {

    private AdView mAdView;
    private static RecyclerView.Adapter adapter;
    private RecyclerView.LayoutManager layoutManager;
    private static RecyclerView recyclerView;
    public static ArrayList<DictObjectModel> data;
    DatabaseHelper db ;
    ArrayList<String> wordcombimelist;
    ArrayList<String> meancombimelist;
    LinkedHashMap<String,String> namelist;
    SearchView searchView;


    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
        setSupportActionBar(toolbar);



        DrawerLayout drawer = (DrawerLayout) findViewById(R.id.drawer_layout);
        ActionBarDrawerToggle toggle = new ActionBarDrawerToggle(
                this, drawer, toolbar, R.string.navigation_drawer_open, R.string.navigation_drawer_close);
        drawer.setDrawerListener(toggle);
        toggle.syncState();

        NavigationView navigationView = (NavigationView) findViewById(R.id.nav_view);
        navigationView.setNavigationItemSelectedListener(this);


        recyclerView = (RecyclerView) findViewById(R.id.my_recycler_view);
        recyclerView.setHasFixedSize(true);
        db= new DatabaseHelper(this);
        searchView = (SearchView) findViewById(R.id.searchView);
        searchView.setQueryHint("Search Here");
        searchView.setQueryRefinementEnabled(true);
        layoutManager = new LinearLayoutManager(this);
        recyclerView.setLayoutManager(layoutManager);
        recyclerView.setItemAnimator(new DefaultItemAnimator());
        data = new ArrayList<DictObjectModel>();
        fetchData();

        // Banner Ads

        mAdView = (AdView) findViewById(R.id.adView);
        AdRequest adRequest = new AdRequest.Builder().build();
        mAdView.loadAd(adRequest);


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

            @Override
            public boolean onQueryTextChange(String newText) {


                newText = newText.toLowerCase();

                final ArrayList<DictObjectModel> filteredList = new ArrayList<DictObjectModel>();

                for (int i = 0; i < wordcombimelist.size(); i++) {

                    final String text = wordcombimelist.get(i).toLowerCase();
                    if (text.contains(newText)) {

                        filteredList.add(new DictObjectModel(wordcombimelist.get(i),meancombimelist.get(i)));
                    }
                }
                adapter = new CustomAdapter(filteredList);
                recyclerView.setAdapter(adapter);


                return true;
            }
        });


    }
    public void fetchData()
    {
        db =new DatabaseHelper(this);
        try {

            db.createDataBase();
            db.openDataBase();

        }
        catch (Exception e)
        {
            e.printStackTrace();
        }


        namelist=new LinkedHashMap<>();
        int ii;
        SQLiteDatabase sd = db.getReadableDatabase();
        Cursor cursor = sd.query("Dictionary1" ,null, null, null, null, null, null);
        ii=cursor.getColumnIndex("word");
        wordcombimelist=new ArrayList<String>();
        meancombimelist= new ArrayList<String>();
        while (cursor.moveToNext()){
            namelist.put(cursor.getString(ii), cursor.getString(cursor.getColumnIndex("definition")));
        }
        Iterator entries = namelist.entrySet().iterator();
        while (entries.hasNext()) {
            Map.Entry thisEntry = (Map.Entry) entries.next();
            wordcombimelist.add(String.valueOf(thisEntry.getKey()));
            meancombimelist.add("- "+String.valueOf(thisEntry.getValue()));
        }

        for (int i = 0; i < wordcombimelist.size(); i++) {
            data.add(new DictObjectModel(wordcombimelist.get(i), meancombimelist.get(i)));
        }
        adapter = new CustomAdapter(data);
        recyclerView.setAdapter(adapter);

    }


    @Override
    public void onBackPressed() {
        DrawerLayout drawer = (DrawerLayout) findViewById(R.id.drawer_layout);
        if (drawer.isDrawerOpen(GravityCompat.START)) {
            drawer.closeDrawer(GravityCompat.START);
        } else {
            super.onBackPressed();
        }
    }