IndexedFragmentPagerAdapter.java

import android.support.v4.app.FragmentManager;
import android.support.v4.app.FragmentPagerAdapter;
import android.support.v4.util.SparseArrayCompat;
import android.view.ViewGroup;

public abstract class IndexedFragmentPagerAdapter<T> extends FragmentPagerAdapter {
    private SparseArrayCompat<T> fragments = new SparseArrayCompat<>();

    public IndexedFragmentPagerAdapter(FragmentManager fm) {
        super(fm);
    }

    @Override
    public Object instantiateItem(ViewGroup container, int position) {
        @SuppressWarnings("unchecked")
        T fragment = (T) super.instantiateItem(container, position);
        fragments.put(position, fragment);
        return fragment;
    }

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

    public T getFragmentAtPosition(int position) {
        return fragments.get(position);
    }
}