交换选项卡时未获取数据

Posted 2023-04-18

【中文标题】交换选项卡时未获取数据

【英文标题】：Data is not fetching when swap the tab

【发布时间】：2018-05-26 01:27:08

【问题描述】：

我已经实现了一个应用程序，其中有 7 个选项卡，当用户滚动列表时，我使用 addOnScrollListener 来获取数据。我的问题是当我将一个fragment 或标签移动到另一个fragment 然后返回到之前的标签时，数据不会第二次出现在该标签上。

下面是我的片段类

public class EI_Pending_Fragment extends Fragment
SessionManager session;

private List<SuperHero> listSuperHeroes;
private RecyclerView recyclerView;
private RecyclerView.LayoutManager layoutManager;
private RecyclerView.Adapter adapter;
public ProgressBar progressBar;
private RequestQueue requestQueue;
private int requestCount1 = 1;
private Boolean isStarted = false;
private Boolean isVisible = false;
public String email;

public EI_Pending_Fragment() 


@Override
public void onStart() 
    super.onStart();
    isStarted = true;
    if (isVisible && isStarted)
        getData();
    


@Override
public void setUserVisibleHint(boolean isVisibleToUser) 
    super.setUserVisibleHint(isVisibleToUser);
    isVisible = isVisibleToUser;
    if (isStarted && isVisible) 
        getData();
    



@Override
public void onCreate(Bundle savedInstanceState) 
    super.onCreate(savedInstanceState);


@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) 
    View view= inflater.inflate(R.layout.activity_main_test, container, false);

    session = new SessionManager(getActivity());
    // get user data from session
    HashMap<String, String> user = session.getUserDetails();
    email = user.get(SessionManager.KEY_EMAIL);
    return view;


public void onViewCreated(View v, Bundle savedInstanceState) 
    super.onViewCreated(v, savedInstanceState);

    recyclerView = (RecyclerView) v.findViewById(R.id.recyclerView);
    recyclerView.setHasFixedSize(true);
    layoutManager = new LinearLayoutManager(getContext());
    recyclerView.setLayoutManager(layoutManager);
    listSuperHeroes = new ArrayList<>();
    requestQueue = Volley.newRequestQueue(getContext());
    //   getData();
    adapter = new CardAdapter(listSuperHeroes, getActivity());
    recyclerView.setAdapter(adapter);
    progressBar = (ProgressBar) v.findViewById(R.id.progressBar1);

    recyclerView.addOnScrollListener(new RecyclerView.OnScrollListener() 
        @Override
        public void onScrollStateChanged(RecyclerView recyclerView, int
                newState) 
            super.onScrollStateChanged(recyclerView, newState);
            if (isLastItemDisplaying(recyclerView)) 
                if(requestCount1==1)
                    exit();
                
                else 
                    getData();
                
            
        
    );


private JsonArrayRequest getDataFromServer(int requestCount) 
    Log.e("email",email);
    final String DATA_URL = "http://192.168.2.110/xp/ei_pending_received.php?matri_id="+email+"&page=";
    JsonArrayRequest jsonArrayRequest = new JsonArrayRequest(DATA_URL + String.valueOf(requestCount),
            new Response.Listener<JSONArray>() 
                @Override
                public void onResponse(JSONArray response) 
                    Log.e("response",response.toString());
                    if(response.length()==0)
                        requestCount1 = 1;

                    
                    else 
                        parseData(response);
                        progressBar.setVisibility(View.GONE);
                    

                
            ,
            new Response.ErrorListener() 
                @Override
                public void onErrorResponse(VolleyError error) 
                    progressBar.setVisibility(View.GONE);
                    Toast.makeText(getActivity(), "No More Items Available", Toast.LENGTH_SHORT).show();
                
            );
    return jsonArrayRequest;


private void getData() 
    requestQueue.add(getDataFromServer(requestCount1));
    requestCount1++;


private void parseData(JSONArray array) 
    for (int i = 0; i < array.length(); i++) 
        //Log.e("array",array.toString().trim());
        SuperHero superHero = new SuperHero();
        JSONObject json = null;
        try 
            json = array.getJSONObject(i);
            superHero.setImageUrl(json.getString(Config_Test.TAG_IMAGE_URL));
            superHero.setMglId(json.getString(Config_Test.TAG_MGLID));
            superHero.setAge(json.getString(Config_Test.TAG_AGE));
            superHero.setAgeHeight(json.getString(Config_Test.TAG_HEIGHT));
            superHero.setCommunity(json.getString(Config_Test.TAG_COMMUNITY));
            superHero.setCaste(json.getString(Config_Test.TAG_CASTE));
            superHero.setOccupation(json.getString(Config_Test.TAG_OCCUPATION));
            superHero.setIncome(json.getString(Config_Test.TAG_INCOME));
            superHero.setStatus(json.getString(Config_Test.TAG_STATUS));
            superHero.setRequested_On(json.getString(Config_Test.TAG_REQUESTED_ON));

         catch (JSONException e) 
            e.printStackTrace();
        
        listSuperHeroes.add(superHero);
    
    adapter.notifyDataSetChanged();

private boolean isLastItemDisplaying(RecyclerView recyclerView) 
    if (recyclerView.getAdapter().getItemCount() != 0) 
        int lastVisibleItemPosition = ((LinearLayoutManager) recyclerView.getLayoutManager()).findLastCompletelyVisibleItemPosition();
        if (lastVisibleItemPosition != RecyclerView.NO_POSITION && lastVisibleItemPosition == recyclerView.getAdapter().getItemCount() - 1)
            return true;
    
    return false;

void exit()
    Toast.makeText(getContext(),"no more data avilable",Toast.LENGTH_SHORT).show();
 
 

下面是我添加所有选项卡的 Activity 类

private void setupViewPager(ViewPager viewPager) 
    int numberOfPages=7;
    ViewPagerAdapter adapter = new ViewPagerAdapter(getSupportFragmentManager());
    adapter.addFragment(new NewMatches_Tab(), "New matches");
    adapter.addFragment(new Broader_Match_Tab(), "Broader Matches");
    adapter.addFragment(new Similar_Matchs_Tab(), "Similar Matches");
    adapter.addFragment(new ShortlistTab(), "ShortListed");
    adapter.addFragment(new Viewed_My_Profile(), "View My Profile");
    adapter.addFragment(new ShortListedMeTab(), "ShortListed Me");
    adapter.addFragment(new Photo_Request_Received(), "Photo Request Received");
    //viewPager.setOffscreenPageLimit(numberOfPages);
    viewPager.setAdapter(adapter);
  

【问题讨论】：

发布你的活动，它在一个浏览器中包含所有 7 个片段

尊敬的先生，检查我更新的问题

将你的片段onCreate代码移动到onResume或活动viewpager.setoffscreenlimit(7)

取消注释这一行 viewPager.setOffscreenPageLimit(7);

当我取消注释这一行时，当应用程序打开时，所有片段的数据都会在第一次加载

【参考方案1】：

您可以在活动中添加一个 OnPageChangeListener 并将其注册到您的视图寻呼机并在 OnPageChangeListener 实例中进行所有必要的“设置”。

ViewPager.OnPageChangeListener viewPagerPageChangeListener = new ViewPager.OnPageChangeListener() 

    @Override
    public void onPageSelected(int position) 
        //Do your fragment refreshing here
        mCurrentPage = position;
    

    @Override
    public void onPageScrolled(int arg0, float arg1, int arg2) 

    

    @Override
    public void onPageScrollStateChanged(int arg0) 

    
;

@Override
public void setFragmentsForContents(List<Content> contents)  //bundle data for your different fragments
    if(contents!=null)
        NUM_PAGES = contents.size();
        mContentPager.addOnPageChangeListener(viewPagerPageChangeListener);
        mContentPager.setAdapter(mScreenSlidePagerAdapter);
        mContentPager.setCurrentItem(mCurrentPage);
    


private class ScreenSlidePagerAdapter extends FragmentStatePagerAdapter 
    ScreenSlidePagerAdapter(FragmentManager fm) 
        super(fm);
    

    @Override
    public Fragment getItem(int position) 
        return ContentFragment.newInstance(mContents.get(position).getContent());
    

    @Override
    public int getCount() 
        return NUM_PAGES;
    

    @NonNull
    @Override
    public Object instantiateItem(ViewGroup container, int position) 
        return super.instantiateItem(container, position);
    

    @Override
    public float getPageWidth(int position) 
        return 1.0f;