public class MainActivity extends FragmentActivity implements PianoItemListener {
    private PianoView pianoView;
    private List<String> iconUrlList;
    private PianoAdapter pianoAdapter;

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

        iconUrlList = new ArrayList<>();
        pianoView = (PianoView) findViewById(R.id.piano_view);
        pianoView.setScrollPianoStartDelayTime(400);
        pianoView.setPianoItemListenerListener(this);

        fetchData();
        pianoView.showPianoAtPosition(0);
    }

    private void fetchData() {
        for (int i = 0; i < 10; i++) {
            iconUrlList.add("http://img5.duitang.com/uploads/item/201409/07/20140907080946_d4QiL.jpeg");
        }
        pianoAdapter = new PianoAdapter(this, pianoView);
        pianoView.setAdapter(pianoAdapter);
        pianoAdapter.addIconUrlList(iconUrlList);
    }

    @Override
    public void onPianoItemSelected(int itemIndex) {
        Toast.makeText(this, "item " + itemIndex + " selected", Toast.LENGTH_SHORT).show();
        pianoView.showPianoAtPosition(itemIndex);
    }

    @Override
    public void onStartSwipe() {
    }
}