public class InputFragmentsPagerAdapter extends FragmentPagerAdapter {
    private SparseArray<Fragment> registeredFragments = new SparseArray<Fragment>();
    private int mCurrentCountUsingDisplay;

    public InputFragmentsPagerAdapter(FragmentManager fm, int countUsingDisplay) {
        super(fm);
        mCurrentCountUsingDisplay = countUsingDisplay;
    }

    @Override
    public Fragment getItem(int position) {
        Fragment fragment = registeredFragments.get(position);
        if(fragment==null){
            switch (position){
                case 0:
                    fragment = new Fragment1();
                    break;
                case 1:
                    fragment = new Fragment2();
                    break;
            }
        }
        return fragment;
    }

    @NonNull
    @Override
    public Object instantiateItem(ViewGroup container, int position) {
        Fragment createdFragment = (Fragment) super.instantiateItem(container, position);
        registeredFragments.put(position,createdFragment);
        return createdFragment;
    }

    @Override
    public void destroyItem(ViewGroup container, int position, Object object) {
        registeredFragments.remove(position);
        super.destroyItem(container,position,object);
    }

    @Override
    public int getCount() {
        return mCurrentCountUsingDisplay;
    }

    public View getFragmentView(int fragmentIndex) {
        return ((Fragment) registeredFragments.get(fragmentIndex)).getView();
    }
}