你需要改变instantiateItem的mFragments元素getItemPosition。

    if (mFragments.size() > position) {
        Fragment f = mFragments.get(position);

        if (f != null) {
            int newPosition = getItemPosition(f);
            if (newPosition == POSITION_UNCHANGED) {
                return f;
            } else if (newPosition == POSITION_NONE) {
                mFragments.set(position, null);
            } else {
                mFragments.set(newPosition, f);
            }
        }
    }

基于AndroidX FragmentStatePagerAdapter.java，因为mFragments的元素位置在调用notifyDataSetChanged()时不会改变。

来源: https://github.com/cuichanghao/infivt/blob/master/library/src/main/java/cc/cuichanghao/library/FragmentStatePagerChangeableAdapter.java

例子: https://github.com/cuichanghao/infivt/blob/master/app/src/main/java/cc/cuichanghao/infivt/MainActivityChangeablePager.kt

您可以运行这个项目来确认如何工作。 https://github.com/cuichanghao/infivt

I have lived same problem and I have searched too much times. Any answer given in stackoverflow or via google was not solution for my problem. My problem was easy. I have a list, I show this list with viewpager. When I add a new element to head of the list and I refresh the viewpager nothings changed. My final solution was very easy anybody can use. When a new element added to list and want to refresh the list. Firstly set viewpager adapter to null then recreate the adapter and set i to it to viewpager.

myVPager.setAdapter(null);
myFragmentAdapter = new MyFragmentAdapter(getSupportFragmentManager(),newList);
myVPager.setAdapter(myFragmentAdapter);

确保您的适配器必须扩展FragmentStatePagerAdapter

我遇到过这个问题，今天终于解决了，所以我把我学到的东西写下来，希望对那些刚接触Android ViewPager并像我一样更新的人有帮助。我使用FragmentStatePagerAdapter在API级别17，目前只有2个片段。我想一定有什么地方不对，请指正，谢谢。

Serialized data has to be loaded into memory. This can be done using a CursorLoader/AsyncTask/Thread. Whether it's automatically loaded depends on your code. If you are using a CursorLoader, it's auto-loaded since there is a registered data observer. After you call viewpager.setAdapter(pageradapter), the adapter's getCount() is constantly called to build fragments. So if data is being loaded, getCount() can return 0, thus you don't need to create dummy fragments for no data shown. After the data is loaded, the adapter will not build fragments automatically since getCount() is still 0, so we can set the actually loaded data number to be returned by getCount(), then call the adapter's notifyDataSetChanged(). ViewPager begin to create fragments (just the first 2 fragments) by data in memory. It's done before notifyDataSetChanged() is returned. Then the ViewPager has the right fragments you need. If the data in the database and memory are both updated (write through), or just data in memory is updated (write back), or only data in the database is updated. In the last two cases if data is not automatically loaded from the database to memory (as mentioned above). The ViewPager and pager adapter just deal with data in memory. So when data in memory is updated, we just need to call the adapter's notifyDataSetChanged(). Since the fragment is already created, the adapter's onItemPosition() will be called before notifyDataSetChanged(） returns. Nothing needs to be done in getItemPosition(). Then the data is updated.

而不是从getItemPosition()返回POSITION_NONE并引起完整的视图重建，这样做:

//call this method to update fragments in ViewPager dynamically
public void update(UpdateData xyzData) {
    this.updateData = xyzData;
    notifyDataSetChanged();
}

@Override
public int getItemPosition(Object object) {
    if (object instanceof UpdateableFragment) {
        ((UpdateableFragment) object).update(updateData);
    }
    //don't return POSITION_NONE, avoid fragment recreation. 
    return super.getItemPosition(object);
}

你的片段应该实现UpdateableFragment接口:

public class SomeFragment extends Fragment implements
    UpdateableFragment{

    @Override
    public void update(UpdateData xyzData) {
         // this method will be called for every fragment in viewpager
         // so check if update is for this fragment
         if(forMe(xyzData)) {
           // do whatever you want to update your UI
         }
    }
}

以及界面:

public interface UpdateableFragment {
   public void update(UpdateData xyzData);
}

你的数据类:

public class UpdateData {
    //whatever you want here
}

在代码中的notifyDataSetChanged()之后尝试在ViewPager上销毁drawingcache()。

我已经浏览了上面所有的答案和其他一些帖子，但仍然找不到适合我的东西(不同的片段类型以及动态添加和删除选项卡)。FWIW遵循的方法对我来说是有效的(以防其他人有同样的问题)。

public class MyFragmentStatePageAdapter extends FragmentStatePagerAdapter {
    private static final String TAB1_TITLE = "Tab 1";
    private static final String TAB2_TITLE = "Tab 2";
    private static final String TAB3_TITLE = "Tab 3";

    private ArrayList<String> titles = new ArrayList<>();
    private Map<Fragment, Integer> fragmentPositions = new HashMap<>();


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


    public void update(boolean showTab1, boolean showTab2, boolean showTab3) {
        titles.clear();

        if (showTab1) {
            titles.add(TAB1_TITLE);
        }
        if (showTab2) {
            titles.add(TAB2_TITLE);
        }
        if (showTab3) {
            titles.add(TAB3_TITLE);
        }
        notifyDataSetChanged();
    }


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

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

        String tabName = titles.get(position);
        if (tabName.equals(TAB1_TITLE)) { 
            fragment =  Tab1Fragment.newInstance();
        } else if (tabName.equals(TAB2_TITLE)) {
            fragment =  Tab2Fragment.newInstance();
        } else if (tabName.equals(TAB3_TITLE)) {
            fragment =  Tab3Fragmen.newInstance();
        } 

        ((BaseFragment)fragment).setTitle(tabName);
        fragmentPositions.put(fragment, position);
        return fragment;
    }

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

    @Override
    public int getItemPosition(Object item) {
        BaseFragment fragment = (BaseFragment)item;
        String title = fragment.getTitle();
        int position = titles.indexOf(title);

        Integer fragmentPosition = fragmentPositions.get(item);
        if (fragmentPosition != null && position == fragmentPosition) {
            return POSITION_UNCHANGED;
        } else {
            return POSITION_NONE;
        }
    }

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