Tabs + ViewPager + FragmentStatePagerAdapter - How

问题:

I'm using the "Tabs + Swipe" project and I'm having a difficult time removing a fragment.

Steps I'm doing:

1. Remove tab from database
2. Remove tab from the FragmentStatePagerAdapter data source
3. Remove tab from the actionBar.
4. Remove fragment using Support FragmentManager.

The problem: After I perform the remove, for some reason, I can still scroll to the right and see an empty fragment. I can't select it, it just bounces back. It seems like the fragment is not being removed but rather changes its position to the tag from the left.

My Adapter:

public class SectionsPagerAdapter extends FragmentStatePagerAdapter {

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

        @Override
        public Fragment getItem(int position) {
            Fragment fragment = new TabFragment();

            Bundle args = new Bundle();
            args.putInt(TabFragment.ARG_TAB_POSITION, position);
            fragment.setArguments(args);

            return fragment;
        }

        @Override
        public int getCount() {
            return tabsList.size();
        }

        @Override
        public CharSequence getPageTitle(int position) {
            return tabsList.get(position).getTitle();
        }

        @Override
        public void destroyItem(ViewGroup container, int position, Object object) {
            super.destroyItem(container, position, object);
            FragmentManager manager = ((Fragment)object).getFragmentManager();
            android.support.v4.app.FragmentTransaction trans = manager.beginTransaction();
            trans.remove((Fragment)object);
            trans.commit();
        }
    }

My remove method (called from within the fragment):

public void removeTab() {
            mTabTableHandler.deleteTab(tab.getId()); //db
            tabsList.remove(tabPosition); //data source
            actionBar.removeTabAt(tabPosition); // actionbar

            getActivity().getSupportFragmentManager().beginTransaction().remove(this).commit(); // support fragmentmanager

            tabsList = mTabTableHandler.query(); //requery db
            mSectionsPagerAdapter.notifyDataSetChanged(); //notify adapter
        }

Appreciate the help!

回答1:

you can find the answer here - Remove Fragment Page from ViewPager in Android

it seems what missing in your code is overwriting of the following adapter's method:

@Override
public int getItemPosition(Object object){
    return PagerAdapter.POSITION_NONE;
}

explanation why such "weird" solution works you can find in the answer to the question in the link I provided you.

回答2:

public void removeAllFragments(ViewGroup container) {
        /*
         * keep this line because section pager adapter has
         * the bug to not delete the last fragment completely
         * -> so we add an empty fragment
         */
        int iStart = 0;

        addFragment(new Fragment());
        Fragment frag;
        int size = fragments.size();
        for (int iPos = iStart; iPos < size; iPos++) {
            frag = getItem(iStart);
            if (frag.isAdded()) {
                destroyItem(container, iStart, frag);
            }
            fragments.remove(frag);
            notifyDataSetChanged();
        }
    }