/**
 * Initializes ViewPager, it's adapter and page indicator view
 */
private void initializePager(){
    mPager = findViewById(R.id.pager);
    mPagerAdapter = new DataViewerAdapter(getSupportFragmentManager());
    mPagerAdapter.initialize();
    mPager.setAdapter(mPagerAdapter);
    PageIndicatorView pageIndicatorView = findViewById(R.id.pageIndicatorView);
    pageIndicatorView.setViewPager(mPager);
}
 

@NonNull
@Override
public Dialog onCreateDialog(Bundle savedInstanceState) {
    //get initial value from pref
    if (preference instanceof StylePreference) {
        selectedStyle = ((StylePreference) preference).getStyle();
    }

    styles = getContext().getResources().getIntArray(R.array.style_values);

    @SuppressLint("InflateParams")
    View view = LayoutInflater.from(getContext()).inflate(R.layout.pref_dialog_style, null);

    ViewPager viewPager = view.findViewById(R.id.view_pager);
    viewPager.setAdapter(new ViewPagerAdapter(getContext()));
    viewPager.addOnPageChangeListener(new ViewPager.SimpleOnPageChangeListener() {
        @Override
        public void onPageSelected(int position) {
            super.onPageSelected(position);
            selectedStyle = styles[position];
        }
    });

    int currentItem = 0;
    for (int i = 0; i < styles.length; i++) {
        if (styles[i] == selectedStyle) {
            currentItem = i;
            break;
        }
    }

    viewPager.setCurrentItem(currentItem);

    PageIndicatorView indicator = view.findViewById(R.id.indicator);
    indicator.setAnimationType(AnimationType.WORM);

    return new AlertDialog.Builder(getContext())
            .setTitle(R.string.style)
            .setView(view)
            .setPositiveButton(R.string.ok, this)
            .setNegativeButton(R.string.cancel, null)
            .create();
}