Question

我的ViewPager无效。我不知道我的代码有什么问题。我在使用Fragments：

时遇到了一些问题

基本上，我有一个名为Fragment的{{1}}有一个列表，在列表项的点击事件中，我移动到名为MyListFragment的第二个Fragment FlowersFragment包含三个项目（另外三个ViewPager）。我的Fragments中有一个Button，点击FlowersFragment后，我移动到名为Button的第三个屏幕。现在我有一个问题：

如果我从WelcomeFragment返回FlowersFragment，那么在经过一些研究后我得到了一个像WelcomeFragment这样的解决方案时，它会从Fragments丢失一些ViewPager适配器。这对我的寻呼机很有用childFragmentManager现在正在我的Fragments寻呼机中正确显示。但是，如果我回到FlowersFragment并点击MyListFragment的第二项或第三项，它会显示我的异常，但没有活动。

这是我的名为ListFragment

的FirstFragment

MyListFragment

这是我的public class MyListFragment extends Fragment{ private View view; private FragmentManager fm; private FragmentTransaction ft; private ListView listviewPlaces; private FloristAdapter adapter; private ArrayList<FloristItems> items = new ArrayList<FloristItems>(); private FlowersFragment frag; @Override public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) { inflater = LayoutInflater.from(getActivity()); view = inflater.inflate(R.layout.fragment_list, container,false); listviewPlaces = (ListView)view.findViewById(R.id.listviewPlaces); return view; } @Override public void onActivityCreated(Bundle savedInstanceState) { super.onActivityCreated(savedInstanceState); for (int i = 0; i < 10; i++) { FloristItems florist = new FloristItems(); florist.away = "3 miles away"; florist.title = "Florist Flowers"; florist.price = "$45"; items.add(florist); } adapter = new FloristAdapter(getActivity().getApplicationContext(), items); listviewPlaces.setAdapter(adapter); listviewPlaces.setOnItemClickListener(new OnItemClickListener() { @Override public void onItemClick(AdapterView<?> parent, View view, int position, long id) { if(frag == null){ frag = new FlowersFragment(); } handleFragments(frag); } }); } private void handleFragments(Fragment fragment){ fm = getActivity().getSupportFragmentManager(); ft = fm.beginTransaction(); ft.replace(R.id.frame_container, fragment); ft.addToBackStack(null); ft.commit(); } }类，其中包含三个片段的视图寻呼机：

FlowersFragment

这是我的寻呼机适配器类：

public class FlowersFragment extends Fragment{
private View view;
private FragmentManager fm;
private FragmentTransaction ft;
private ViewPager pager;
private Button btnSendThatFlower;
private FlowerPagerAdapter pageAdapter;
private WelcomeFragment welcomeFrag;


@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
        Bundle savedInstanceState) {

    inflater = LayoutInflater.from(getActivity());
    view = inflater.inflate(R.layout.fragment_choose_flower_buyer, container,false);

    pager = (ViewPager)view.findViewById(R.id.viewpager);
    btnSendThatFlower = (Button)view.findViewById(R.id.btnSendThatFlower);

    return view;
}

@Override
public void onActivityCreated(Bundle savedInstanceState) {
    super.onActivityCreated(savedInstanceState);

    pageAdapter = new FlowerPagerAdapter(getActivity().getSupportFragmentManager());
    pager.setAdapter(pageAdapter);

    btnSendThatFlower.setOnClickListener(new OnClickListener() {

        @Override
        public void onClick(View v) {
            if(welcomeFrag == null){
                welcomeFrag = new WelcomeFragment();
            }
            handleFragments(welcomeFrag);
        }
    });

}

private void handleFragments(Fragment fragment){

    fm = getActivity().getSupportFragmentManager();
    ft = fm.beginTransaction();
    ft.replace(R.id.frame_container, fragment);
    ft.addToBackStack(null);
    ft.commit();
}   }

public class FlowerPagerAdapter extends FragmentPagerAdapter{ private ArrayList<Fragment> pagerItems; public FlowerPagerAdapter(FragmentManager fm) { super(fm); pagerItems = new ArrayList<Fragment>(); pagerItems.add(FlowerImage1.getInstance()); pagerItems.add(FlowerImage2.getInstance()); pagerItems.add(CustomFlowerFragment.getInstance()); } @Override public Fragment getItem(int num) { if (num == 0) { return new FlowerImage1(); } else if(num == 1) { return new FlowerImage2(); } else{ return new CustomFlowerFragment.getInstance(); } } @Override public int getCount() { return pagerItems.size(); } @Override public void restoreState(Parcelable state, ClassLoader loader) { //super.restoreState(state, loader); }} FlowerImage1 FlowerImage1是仅包含CustomFlowerFragment的片段。

这是我的最后一个片段imageview

WelcomeFragment

当我按下后按，然后它在viewpager中没有显示片段，但在浏览器上滑动后，它只显示第一个或有时是最后一个寻呼机片段。

Answer 1

我也面临同样的问题，最后在片段适配器中添加了以下代码。

@Override
public void restoreState(Parcelable state, ClassLoader loader) {
    //super.restoreState(state, loader);
}

Answer 2

我也遇到了同样的问题，但我通过扩展＆＃34; FragmentStatePagerAdapter＆＃34;来修复它。而不是FragmentPagerAdapter。对于你的情况，它将是：

＆＃13;

public class FlowerPagerAdapter extends FragmentStatePagerAdapter{

private ArrayList<Fragment> pagerItems;

public FlowerPagerAdapter(FragmentManager fm) {
    super(fm);
    pagerItems = new ArrayList<Fragment>();
    pagerItems.add(FlowerImage1.getInstance());
    pagerItems.add(FlowerImage2.getInstance());
    pagerItems.add(CustomFlowerFragment.getInstance());

}


@Override
public Fragment getItem(int num) {
     if (num == 0) {
         return new FlowerImage1();
     }
     else if(num == 1) {
         return new FlowerImage2();
     }
     else{
         return new CustomFlowerFragment.getInstance();
     }
}
@Override
public int getCount() {
    return pagerItems.size();
}
}

＆＃13;

Viewpager不使用片段

2 个答案: