ChordsListActivity.java

// Class sending the list

public class ChordsListActivity extends AppCompatActivity implements PopupMenu.OnMenuItemClickListener {

    ArrayList<Accordo> chords;

    ImageButton cerca;

    RecyclerView recyclerView;


    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_chords_list);

        /** Lista di accordi */
        chords = new ArrayList<>();
        ChordsList list = new ChordsList();
        list.createList();
        chords = list.getList();


        /** gestisce le pubblicita */
        MobileAds.initialize(getApplicationContext(), "ca-app-pub-3940256099942544/6300978111");

        AdView listBanner = (AdView) findViewById(R.id.chords_list_banner);
        AdRequest adRequest = new AdRequest.Builder().build();
        listBanner.loadAd(adRequest);


        /** sistema la lista nella RecyclerView */
        recyclerView = (RecyclerView) findViewById(R.id.chords_recycler);
        recyclerView.setLayoutManager(new LinearLayoutManager(ChordsListActivity.this, LinearLayoutManager.VERTICAL, false));
        recyclerView.setHasFixedSize(true);

        final ChordsListAdapter adapter = new ChordsListAdapter (this, chords);
        recyclerView.setAdapter(adapter);

        /** gestisce cosa succede quando un elemento della RecyclerView viene toccato */
        ItemClickSupport.addTo(recyclerView).setOnItemClickListener(new ItemClickSupport.OnItemClickListener(){
            @Override
            public void onItemClicked(RecyclerView recyclerView, int position, View v) {
                Intent intent = new Intent(ChordsListActivity.this, ChordActivity.class);

                Bundle bundle = new Bundle();
                bundle.putParcelable("selected", chords.get(position));
                intent.putExtras(bundle);
                startActivity(intent);
            }
        });



        /** legge il valore di Show_Dialog e se e' falso fa apparire la legenda */
        SharedPreferences sharedPref = PreferenceManager.getDefaultSharedPreferences(this);
        Boolean showDialog = sharedPref.getBoolean("Show_dialog", true);

        Intent legendaIntent = new Intent(ChordsListActivity.this, PopUpInfoActivity.class);

        if(showDialog)
            startActivity(legendaIntent);

        /** gestisce cosa succede quando si preme il tasto cerca */
        cerca = (ImageButton) findViewById(R.id.search);

        cerca.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                Intent intent = new Intent(ChordsListActivity.this, SearchActivity.class);

                Bundle bundle = new Bundle();
                bundle.putParcelableArrayList("chords", chords);
                intent.putExtras(bundle);
                startActivity(intent);
            }
        });}

    /** gestisce cosa succede quando clicco il tasto menu */

    public void showMenu(View v) {
        PopupMenu menu = new PopupMenu(this, v);
        menu.setOnMenuItemClickListener(this);
        menu.inflate(R.menu.menu);
        menu.show();
    }

    @Override
    public boolean onMenuItemClick(MenuItem item) {
        switch (item.getItemId()) {
            case R.id.informazioni_menu:
                Intent intent = new Intent(ChordsListActivity.this, Info.class);
                startActivity(intent);
                return true;

            case R.id.legenda_menu:
                Intent legendaIntent = new Intent(ChordsListActivity.this, PopUpInfoActivity.class);
                startActivity(legendaIntent);
                return true;

            case R.id.premium_menu:
                Intent premiumIntent = new Intent(ChordsListActivity.this, Premium.class);
                startActivity(premiumIntent);
                return true;

            case R.id.problema_menu:
                Intent email = new Intent(Intent.ACTION_SENDTO, Uri.fromParts(
                        "mailto", "dancam.dev@gmail.com", null));
                email.putExtra(Intent.EXTRA_SUBJECT, "Chords Problem");
                email.putExtra(Intent.EXTRA_TEXT, true);
                startActivity(Intent.createChooser(email, "Choose an email client: "));
                return true;

            default:
                return false;
        }
    }
}

SearchActivity.java

//class getting the List


public class SearchActivity extends AppCompatActivity {

    ArrayList<Accordo> chords;
    int a;
    RecyclerView rv;
    SearchView sv;
    ArrayList<Accordo> filteredModelList;

    @Override
    protected void onCreate(@Nullable Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.search_layout);

        /** gestisce la pubblicita */
        MobileAds.initialize(getApplicationContext(), "ca-app-pub-3940256099942544/6300978111");

        AdView searchBanner = (AdView) findViewById(R.id.search_ad);
        AdRequest adRequest = new AdRequest.Builder().build();
        searchBanner.loadAd(adRequest);

        /**-------------------------------*/

        Intent intent = this.getIntent();
        Bundle bundle = intent.getExtras();
        chords = bundle.getParcelableArrayList("chords");

        sv = (SearchView) findViewById(R.id.testo_ricerca);
        sv.setIconifiedByDefault(false);

        rv = (RecyclerView) findViewById(R.id.lista_ricerca);
        rv.setLayoutManager(new LinearLayoutManager(SearchActivity.this, LinearLayoutManager.VERTICAL, false));
        rv.setHasFixedSize(true);

        final SearchAdapter adapter = new SearchAdapter(this, chords);
        rv.setAdapter(adapter);

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

            @Override
            public boolean onQueryTextChange(String newText) {
                //FILTER AS YOU TYPE
                final List<Accordo> filteredModelList = filter(chords, newText);
                adapter.setFilter(filteredModelList);
                return true;
            }
        });

        /** gestisce cosa succede quando un elemento della lista viene cliccato */
        ItemClickSupport.addTo(rv).setOnItemClickListener(new ItemClickSupport.OnItemClickListener(){
            @Override
            public void onItemClicked(RecyclerView recyclerView, int position, View v) {
                Intent intent = new Intent(SearchActivity.this, ChordActivity.class);
                Bundle bundle = new Bundle();
                bundle.putParcelable("selected", filteredModelList.get(position));
                intent.putExtras(bundle);
                startActivity(intent);
            }
        });

    }

    private List<Accordo> filter(List<Accordo> models, String query) {
        query = query.toLowerCase();

        filteredModelList = new ArrayList<>();
        for (Accordo model : models) {
            final String text = model.getName().toLowerCase();
            if (text.contains(query)) {
                filteredModelList.add(model);
            }
        }
        return filteredModelList;
    }
}