FragmentStatePageAdapter缓存，重新创​​建活动后如何引用旧片段？ （对于前-横向模式）

Question

In my app I got a ViewPager which is showing 3 fragments in a swipe views layout. If the activity is recreated (for example, if I go to landscape mode) I can't get a reference to the fragments anymore.

This is my Adapter

public class TabsPagerAdapter extends FragmentStatePagerAdapter{
    public static final String FRAGMENT_MAP = "fragmentMap";
    private SparseArray<MyFragment> myFragmentMap = new SparseArray<MyFragment>();

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

    @Override
    public Fragment getItem(int arg0) {
        MyFragment fragment = new MyFragment();
        Bundle args = new Bundle();
            String nameOfTab = actionBar.getTabAt(arg0).getText().toString();
            ArrayList<VideoBookmark> listOfFragment = myBookmarkManager.getList(nameOfTab);
        args.putParcelableArrayList(MyFragment.ARG_LIST, listOfFragment);
        fragment.setArguments(args);
        myFragmentMap.put(arg0, fragment);

        return fragment;
    }

    @Override
    //return mytabs.size()???
    public int getCount() {
        return NUM_OF_TABS;
    }

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

    public Fragment getFragment(int key) {
        return myFragmentMap.get(key);
    }

    public SparseArray<MyFragment> getFragmentMap(){
        return myFragmentMap;
    }

    public void setNewFragmentMap(SparseArray<MyFragment> newMap){
        myFragmentMap = newMap;
    }

}

I get null pointer exception in this line

//get current fragment
    int index = myViewPager.getCurrentItem();
    Fragment fragment = myTabsPagerAdapter.getFragment(index);

    EditText title = (EditText) fragment.getView().findViewById(R.id.new_title);

I checked, this is happening because the getItem method is not called, so I guess the adapter reuses old fragments in some way, but how can I access this fragments cache to get my old fragments and to be able to use the findViewById method? Thank you!

Answer 1

getFragmentManager.findFragmentByTag（）// <<-如果要动态管理片段getFragmentManager.findFragmentById（）// <<-如果在布局文件中使用<fragment>。

Answer 2

I'm still not sure of this, but I solved calling instantiateItem(viewpager, position) to get the fragment at the given position. If I got it right this method returns the fragment at the given position if it exists, if not it creates another one (I'm guessing it calls getItem() )