Slider problem with jsonArrayRequest Vollay Attempt to invoke virtual method

I'm building an app and it contains a slider to display items, but I'm having trouble getting this item and adding it to a in>.

I can bring the item (image), but only in the android studio logcat, please, if anyone can help me I'm in need.

Follow the code below:

public class MainActivity extends AppCompatActivity {
   ViewPager viewPager;
    LinearLayout sliderDotspanel;
    private int dotscount;
    private ImageView[] dots;
    List<SliderUtils> sliderImg;


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

        Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
        setSupportActionBar(toolbar);

        initCollapsingToolbar();
        //Slider
        rq = Volley.newRequestQueue(this);

        sliderImg = new ArrayList<>();

        viewPager = (ViewPager) findViewById(R.id.viewPager);

        sliderDotspanel = (LinearLayout) findViewById(R.id.sliderDots);

        sendRequest();


viewPager.addOnPageChangeListener(new ViewPager.OnPageChangeListener() {
            @Override
            public void onPageScrolled(int position, float positionOffset, int positionOffsetPixels) {

            }

            @Override
            public void onPageSelected(int position) {

                for (int i = 0; i < dotscount; i++) {
                    dots[i].setImageDrawable(ContextCompat.getDrawable(getApplicationContext(), R.drawable.nonactive_dot));
                }

                dots[position].setImageDrawable(ContextCompat.getDrawable(getApplicationContext(), R.drawable.active_dot));

            }

            @Override
            public void onPageScrollStateChanged(int state) {

            }
        });

        Timer timer = new Timer();
        timer.scheduleAtFixedRate(new MyTimerTask(), 2000, 4000);


  }

   /**
     * Converting dp to pixel
     */
    private int dpToPx(int dp) {
        Resources r = getResources();
        return Math.round(TypedValue.applyDimension(TypedValue.COMPLEX_UNIT_DIP, dp, r.getDisplayMetrics()));
    }

    public class MyTimerTask extends TimerTask {

        @Override
        public void run() {


            MainActivity.this.runOnUiThread(new Runnable() {
                @Override
                public void run() {

                    if (viewPager.getCurrentItem() == 0) {
                        viewPager.setCurrentItem(1);
                    } else if (viewPager.getCurrentItem() == 1) {
                        viewPager.setCurrentItem(2);
                    } else {
                        viewPager.setCurrentItem(0);
                    }

                }
            });

        }
    }

    public void sendRequest() {
        JsonArrayRequest jsonArrayRequest = new JsonArrayRequest(Request.Method.GET, UrlBase1, null, new com.android.volley.Response.Listener<JSONArray>() {
            @Override
            public void onResponse(JSONArray response) {

                for (int i = 0; i < response.length(); i++) {
                    SliderUtils sliderUtils = new SliderUtils();

                    try {
                        JSONObject jsonObject = response.getJSONObject(i);

                        sliderUtils.setSliderImageUri(jsonObject.getString("thumbnailHd"));
                        Log.e("slider", sliderUtils.getSliderImageUri());
                    } catch (JSONException e) {
                        e.printStackTrace();
                        Log.e("slider", e.getMessage());
                    }
                    sliderImg.add(sliderUtils);
                }

                ViewPageAdapter viewPageAdapter = new ViewPageAdapter(sliderImg, MainActivity.this);

                viewPager.setAdapter(viewPageAdapter);

                dotscount = viewPageAdapter.getCount();
                dots = new ImageView[dotscount];

                for (int i = 0; i < dotscount; i++) {

                    dots[i] = new ImageView(MainActivity.this);
                    dots[i].setImageDrawable(ContextCompat.getDrawable(getApplicationContext(), R.drawable.nonactive_dot));

                    LinearLayout.LayoutParams params = new LinearLayout.LayoutParams(LinearLayout.LayoutParams.WRAP_CONTENT, LinearLayout.LayoutParams.WRAP_CONTENT);

                    params.setMargins(8, 0, 8, 0);
                    sliderDotspanel.addView(dots[i], params);
                }
                dots[0].setImageDrawable(ContextCompat.getDrawable(getApplicationContext(), R.drawable.active_dot));

            }
        }, new com.android.volley.Response.ErrorListener() {
            @Override
            public void onErrorResponse(VolleyError error) {

            }
        });

        rq.add(jsonArrayRequest);
    }

}