Индикатор точек Android ViewPager не перемещается

Я создаю вводный слайдер для своего приложения с окном просмотра и индикатором точек внизу с двумя кнопками для входа в систему и входа в систему. Сначала у меня была ошибка с количеством точек; они умножались каждый раз, когда я смахиваю, тогда точки не двигались, когда я смахиваю.

activity_main.xml:

<RelativeLayout xmlns:android = "http://schemas.android.com/apk/res/android"
xmlns:custom = "http://schemas.android.com/apk/res-auto"
xmlns:tools = "http://schemas.android.com/tools"
android:id = "@+id/activity_intro"
android:layout_width = "match_parent"
android:layout_height = "match_parent">

<android.support.v4.view.ViewPager
    android:id = "@+id/view_pager"
    android:layout_width = "match_parent"
    android:layout_height = "match_parent" />

<LinearLayout
    android:id = "@+id/layoutDots"
    android:layout_width = "wrap_content"
    android:layout_height = "wrap_content"
    android:layout_alignParentBottom = "true"
    android:layout_centerHorizontal = "true"
    android:layout_marginBottom = "80dp"
    android:orientation = "horizontal"></LinearLayout>

<Button
    android:id = "@+id/btn_login"
    android:layout_width = "200dp"
    android:layout_height = "wrap_content"
    android:layout_alignParentBottom = "true"
    android:layout_alignParentEnd = "true"
    android:layout_alignParentRight = "true"
    android:layout_toEndOf = "@+id/btn_join"
    android:layout_toRightOf = "@+id/btn_join"
    android:background = "#C1403D"
    android:onClick = "btnLoginClick"
    android:text = "Se connecter"
    android:textColor = "@android:color/white" />

<Button
    android:id = "@+id/btn_join"
    android:layout_width = "193dp"
    android:layout_height = "wrap_content"
    android:layout_alignParentBottom = "true"
    android:layout_alignParentLeft = "true"
    android:background = "#303952"
    android:onClick = "btnJoinClick"
    android:text = "S'enregistrer"
    android:textColor = "@android:color/white" />

</RelativeLayout>

slide_layout.xml:

простой код слайда:

<RelativeLayout xmlns:android = "http://schemas.android.com/apk/res/android"
android:orientation = "vertical" android:layout_width = "match_parent"
android:layout_height = "match_parent"
android:background = "@color/bg_screen">

<LinearLayout
    android:layout_width = "wrap_content"
    android:layout_height = "wrap_content"
    android:layout_centerInParent = "true"
    android:gravity = "center_horizontal"
    android:orientation = "vertical">

    <TextView
        android:id = "@+id/slide_heading"
        android:text = "header"
        android:textAlignment = "center"
        android:layout_gravity = "center_horizontal"
        android:layout_width = "wrap_content"
        android:layout_height = "wrap_content"
        android:textColor = "@android:color/white"
        android:textSize = "@dimen/slide_title"
        android:textStyle = "bold" />

    <TextView
        android:text = "Description"
        android:id = "@+id/slide_description"
        android:layout_width = "wrap_content"
        android:layout_height = "wrap_content"
        android:layout_marginTop = "20dp"
        android:paddingLeft = "@dimen/desc_padding"
        android:paddingRight = "@dimen/desc_padding"
        android:textAlignment = "center"
        android:textColor = "@android:color/white"
        android:textSize = "17dp" />

</LinearLayout>
</RelativeLayout>

SlidesAdapter.java:

public class SlidesAdapter extends PagerAdapter {

    Context context;

    public SlidesAdapter(Context context) {
        this.context = context;
    }

    public SlidesAdapter() {
    }

    public String [] slide_headings= {
            "Connectez-vous",
            "Gérez vos tâches rapidement",
            "Suivez vos progrés facilement",
            "Accéder aux services de votre université"
    };

    public String [] slide_descriptions = {
            "à \"app name\"",
            "Organisez votre travail et vos études et controlez les\n" +
                    "grâce à un agenda facile à utiliser",
            "Enregistrer les notes de matières et suivez vos progrés",
            "Découvrez les clubs, bibliothéques et les services de votre université"
    };

    @Override
    public int getCount() {
        return slide_headings.length;
    }

    @Override
    public boolean isViewFromObject(View view, Object obj) {
        return view == obj;
    }

    @Override
    public Object instantiateItem(ViewGroup container, int position) {
        LayoutInflater layoutInflater = (LayoutInflater) context.getSystemService(context.LAYOUT_INFLATER_SERVICE);

        View view = layoutInflater.inflate(R.layout.slide_layout, container, false);

        TextView slideHeading = (TextView) view.findViewById(R.id.slide_heading);
        TextView slideDescription = (TextView) view.findViewById(R.id.slide_description);

        slideHeading.setText(slide_headings[position]);
        slideDescription.setText(slide_descriptions[position]);

        ViewPager vp = (ViewPager) container;
        container.addView(view,0);

        return view;
    }

    @Override
    public void destroyItem(ViewGroup container, int position, Object object) {
        ViewPager vp = (ViewPager) container;
        View view = (View) object;
        vp.removeView(view);
    }
}

MainActivity.java:

public class MainActivity extends Activity {

    private ViewPager viewPager;
    private SlidesAdapter slidesAdapter;
    private LinearLayout dotsLayout;
    private TextView[] dots;
    private int[] layouts;
    private Button btnLogin, btnJoin;

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

        viewPager =  findViewById(R.id.view_pager);
        dotsLayout = findViewById(R.id.layoutDots);
        btnLogin = findViewById(R.id.btn_login);
        btnJoin = findViewById(R.id.btn_join);

        slidesAdapter = new SlidesAdapter(this);
        viewPager.setAdapter(slidesAdapter);

        addBottomDots(0);

        viewPager.addOnPageChangeListener(viewListener);

    }

    private void addBottomDots(int position) {

        dots = new TextView[4];

        for (int i = 0; i < dots.length; i++) {
            dots[i] = new TextView(this);
            dots[i].setText(Html.fromHtml("&#8226;"));
            dots[i].setTextSize(35);
            dots[i].setTextColor(getResources().getColor(R.color.dot_inactive));
            dotsLayout.addView(dots[i]);
        }

        if (dots.length>0){
          dots[position].setTextColor(getResources().getColor(R.color.dot_active));
        }
    }

    ViewPager.OnPageChangeListener viewListener = new ViewPager.OnPageChangeListener() {
        @Override
        public void onPageScrolled(int i, float v, int i1) {

        }

        @Override
        public void onPageSelected(int position) {

        }

        @Override
        public void onPageScrollStateChanged(int state) {
        }
    };

}