具有不同选项卡上的列表视图的相同片段

Question

我想创建一个显示 3 个选项卡的 activity。第一个选项卡应该显示用户上传的照片，第二个是用户喜欢的所有图像，第三个是用户最喜欢的图像。所有这些数据都来自 webservice.I 想使用相同的片段及其布局文件并调用不同的 URL。该片段实现了一个 StringReader 并在其中填充了一个列表视图。
我的问题是我设法在第一个选项卡中加载了片段，但第二个和第三个选项卡仍然是空的。如果我导航到最后一个选项卡并开始向后导航，那么第一个选项卡将保持为空，而第二个选项卡将被填充。我看了这么多教程，把我能达到的都标红了，但似乎没有任何帮助。
我的 Activity 中的片段实例化如下所示：

public class SectionsPagerAdapter extends FragmentPagerAdapter {

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

@Override
public Fragment getItem(int position) {
    // getItem is called to instantiate the fragment for the given page.
    // Return a PlaceholderFragment (defined as a static inner class below).
    switch (position) {
        case 0:
            return UsersSpheresFragment.newInstance();
        case 1:
            return UsersSpheresFragment.newInstance();
        case 2:
            return UsersSpheresFragment.newInstance();
        default:
            return  null;
    }
}

@Override
public int getCount() {
    // Show 3 total pages.
    return 3;
}

@Override
public CharSequence getPageTitle(int position) {
    switch (position) {
        case 0:
            return "SECTION 1";
        case 1:
            return "SECTION 2";
        case 2:
            return "SECTION 3";
    }
    return null;
}

}

我的片段是：

public class UsersSpheresFragment extends Fragment {

    CircleImageView userImageFragment;
    TextView userNameTextFragment;
    TextView nrOfSpheresFragment;
    LinearLayout loadingLayoutFragment;
    ListView listview_spheresFragment;
    public PhotosphereListAdapter adapter;
    TextView nrOfLikes;
    TextView nrOfSeens;

    String userId="";
    String userName = "";

    @Nullable
    @Override
    public View onCreateView(LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {
        View view =  inflater.inflate(R.layout.my_spheres_fragment,container,false);
        return view;
    }

    // newInstance constructor for creating fragment with arguments
    public static UsersSpheresFragment newInstance() {
        UsersSpheresFragment fragmentFirst = new UsersSpheresFragment();
        return fragmentFirst;
    }

    @Override
    public void onViewCreated(View view, @Nullable Bundle savedInstanceState) {
        super.onViewCreated(view, savedInstanceState);

        userImageFragment = (CircleImageView) getActivity().findViewById(R.id.userImageFragment);
        userNameTextFragment = (TextView) getActivity().findViewById(R.id.userNameTextFragment);
        nrOfSpheresFragment = (TextView) getActivity().findViewById(R.id.nrOfSpheresFragment);
        loadingLayoutFragment = (LinearLayout) getActivity().findViewById(R.id.loadingLayoutFragment);
        listview_spheresFragment = (ListView) getActivity().findViewById(R.id.listview_spheresFragment);
        nrOfLikes = (TextView)getActivity().findViewById(R.id.nrOfLikes);
        nrOfSeens = (TextView)getActivity().findViewById(R.id.nrOfSeens);

        GlobalUserData userData = (GlobalUserData)getActivity().getApplication();
        Bundle bundle = this.getArguments();

        if (bundle != null) {
            userId = bundle.getString("userId","");
            userName = bundle.getString("userName","");
            userNameTextFragment.setText(userName);
        }
        else{
            if (userData.getUserImageLink().length() > 0) {
                LoadUserImage(userData.getName(), userData.getUserImageLink());
            }
            userNameTextFragment.setText(userData.getName());

        }
        //Log.i("TAG",userData.GetAllData());


        if (userId.length() > 0)
            loadImagesFromAPI(MainActivity.URL_DATA+"typ=mysphere&id="+userId);
        else
            loadImagesFromAPI(MainActivity.URL_DATA+"typ=mysphere&id="+userData.getUserId());

        listview_spheresFragment.setOnItemClickListener(new AdapterView.OnItemClickListener() {
            @Override
            public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
                //send the photosphereId to the Panoviewer fragment
                Bundle bundle = new Bundle();
                bundle.putString("Id", view.getTag().toString());
                bundle.putString("Title", ((Photosphere) adapter.getItem(position)).getTitle());
                bundle.putString("Description", ((Photosphere) adapter.getItem(position)).getDescription());
                bundle.putString("ThumbUrl", ((Photosphere) adapter.getItem(position)).getImageUrl());
                bundle.putBoolean("ShowUserLink", userId.length() > 0 ? false : true);
                //create the fragment
                SimpleFragment fragment = new SimpleFragment();
                fragment.setArguments(bundle);
                FragmentTransaction transaction = getActivity().getSupportFragmentManager().beginTransaction();
                transaction.replace(R.id.content_main, fragment);
                transaction.setTransition(FragmentTransaction.TRANSIT_FRAGMENT_FADE);
                transaction.addToBackStack(null);
                transaction.commit();

            }
        });

    }

    public void LoadUserImage(String userName, String imageUrl){
        ImageLoader imageLoader = CustomVolleyRequest.getInstance(getActivity()).getImageLoader();
        Bitmap bm =  imageLoader.get(imageUrl, ImageLoader.getImageListener(userImageFragment, android.R.color.white, android.R.color.white)).getBitmap();
        userImageFragment.setImageBitmap(bm);
        userNameTextFragment.setText(userName);
    }

    public void loadImagesFromAPI(final String Url) {
        loadingLayoutFragment.setVisibility(View.VISIBLE);
        StringRequest stringRequest = new StringRequest(com.android.volley.Request.Method.GET, Url,
                new Response.Listener<String>() {
                    @Override
                    public void onResponse(String response) {
                        try {
                            ArrayList<Photosphere> photospheres = new ArrayList<>();
                            JSONObject jsonObject = new JSONObject(response);
                            if(jsonObject.isNull("userModel") || jsonObject.getJSONObject("userModel").isNull("OtherImages")){
                                loadingLayoutFragment.setVisibility(View.GONE);
                                nrOfSpheresFragment.setText("No images");
                            }
                            else {
                                if (userId.length() >0){
                                    LoadUserImage((jsonObject.getJSONObject("userModel")).getString("UserName"),(jsonObject.getJSONObject("userModel")).getString("ImgPath"));
                                }
                                photospheres = new WebServiceReader().processSpheresModelJsonData(jsonObject.getJSONObject("userModel"),"OtherImages");
                                loadingLayoutFragment.setVisibility(View.GONE);
                                //init adapter
                                adapter = new PhotosphereListAdapter(getActivity(), photospheres, (userId.length() > 0 ? false : true),true);
                                listview_spheresFragment.setAdapter(adapter);
                                nrOfSpheresFragment.setText(nrOfSpheresFragment.getText()+"("+listview_spheresFragment.getCount()+")");
                                nrOfLikes.setText((jsonObject.getJSONObject("userModel")).getString("TotalLikes"));
                                nrOfSeens.setText((jsonObject.getJSONObject("userModel")).getString("TotalViews"));
                            }

                        } catch (JSONException e) {
                            e.printStackTrace();
                        }
                    }
                },
                new Response.ErrorListener() {
                    @Override
                    public void onErrorResponse(VolleyError error) {
                        nrOfSpheresFragment.setText("An error occurred. Please try again!");
                    }
                }
        );

        RequestQueue requestQueue = Volley.newRequestQueue(getActivity());
        requestQueue.add(stringRequest);
    }



    @Override
    public void onDestroy() {
        super.onDestroy();
    }
}

更新！ 似乎在第一个选项卡中加载并覆盖了所有片段。

nrOfSpheresFragment.setText(nrOfSpheresFragment.getText()+"("+listview_spheresFragment.getCount()+")");

这行代码更新了一个文本视图，我可以看到文本视图更新了 3 次 (25)(10)(5)，这表示结果数。只有最后一个结果的列表视图可见

Answer 1

您可以将变量设置为片段，帮助您选择您需要的内容

private String mUrl; //url of content 

//set url of content via newInstanse() method
public static UsersSpheresFragment newInstance(String dataUrl) {
    UsersSpheresFragment fragment = new UsersSpheresFragment();
    Bundle arguments = new Bundle();
    arguments.putInt(EXTRA_KEY_ULR, dataUrl);
    fragment.setArguments(arguments);
    return fragment;
}

//get url in onCreate
@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    Bundle extras = getArguments();
    if (extras == null || !extras.containsKey(EXTRA_KEY_URL))
        throw new IllegalArgumentException("missing authorId argument");

    mUrl = extras.getInt(EXTRA_KEY_URL);

    //load your data 
    webService.loadData(mUrl);
}

另一种变体是通过 newIntanse(int type) 方法设置内容类型，并在 fragment#onCreate()

中选择与其类型匹配的数据

Answer 2

我知道问题出在哪里了。
我在使用fragment的时候，（fragment是之前创建的，用别的方式）没注意到我在页面中初始化控件的时候用的是getactivity()而不是rootview。所以为了让它工作，我改变了这两个，如图所示

   userImageFragment = (CircleImageView) view.findViewById(R.id.userImageFragment);
    userNameTextFragment = (TextView) view.findViewById(R.id.userNameTextFragment);
    nrOfSpheresFragment = (TextView) view.findViewById(R.id.nrOfSpheresFragment);
    loadingLayoutFragment = (LinearLayout) view.findViewById(R.id.loadingLayoutFragment);
    listview_spheresFragment = (ListView) view.findViewById(R.id.listview_spheresFragment);
    nrOfLikes = (TextView)view.findViewById(R.id.nrOfLikes);
    nrOfSeens = (TextView)view.findViewById(R.id.nrOfSeens);

具有不同选项卡上的列表视图的相同片段

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