android - 三个 Fragments 和三个 Recyclerview。数据不显示

Question

我有包含 3 个 fragment 的 MainActivity。数据正在使用 volley 通过 Json 下载。当我运行应用程序时，当我打开键盘时，没有显示任何加载的每个 fragment 。这是我的 MainActivity 代码

public class MainActivity extends AppCompatActivity {

private Toolbar toolbar;
private TabLayout tabLayout;
private ViewPager viewPager;
private RecyclerView myrv ;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    myrv = findViewById(R.id.rv);
    toolbar = (Toolbar) findViewById(R.id.toolbar);
    setSupportActionBar(toolbar);

    getSupportActionBar().setDisplayHomeAsUpEnabled(true);

    viewPager = (ViewPager) findViewById(R.id.viewpager);
    setupViewPager(viewPager);

    tabLayout = (TabLayout) findViewById(R.id.tabs);
    tabLayout.setupWithViewPager(viewPager);
}
private void setupViewPager(ViewPager viewPager) {
    ViewPagerAdapter adapter = new 
ViewPagerAdapter(getSupportFragmentManager());
    adapter.addFragment(new OneFragment(), "Ophthalmic");
    adapter.addFragment(new TwoFragment(), "Contact");
    adapter.addFragment(new ThreeFragment(), "THREE");
    viewPager.setAdapter(adapter);
}
class ViewPagerAdapter extends FragmentPagerAdapter {
    private final List<Fragment> mFragmentList = new ArrayList<>();
    private final List<String> mFragmentTitleList = new ArrayList<>();

    public ViewPagerAdapter(FragmentManager manager) {
        super(manager);
    }

    @Override
    public Fragment getItem(int position) {
        return mFragmentList.get(position);
    }

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

    public void addFragment(Fragment fragment, String title) {
        mFragmentList.add(fragment);
        mFragmentTitleList.add(title);
    }

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

这里是 MainActivity.xml

<?xml version="1.0" encoding="utf-8"?>
    <android.support.design.widget.CoordinatorLayout                 
  xmlns:android="http://schemas.android.com/apk/res/android"
 xmlns:app="http://schemas.android.com/apk/res-auto"
 android:layout_width="match_parent"
 android:layout_height="match_parent">

<android.support.design.widget.AppBarLayout
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:theme="@style/ThemeOverlay.AppCompat.Dark.ActionBar">

<android.support.v7.widget.Toolbar
    android:id="@+id/toolbar"
    android:layout_width="match_parent"
    android:layout_height="?attr/actionBarSize"
    android:background="?attr/colorPrimary"
    app:layout_scrollFlags="scroll|enterAlways"
    app:popupTheme="@style/ThemeOverlay.AppCompat.Light" />

<android.support.design.widget.TabLayout
    android:id="@+id/tabs"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    app:tabMode="fixed"
    app:tabGravity="fill"/>
 </android.support.design.widget.AppBarLayout>

<android.support.v4.view.ViewPager
android:id="@+id/viewpager"
android:layout_width="match_parent"
android:layout_height="match_parent"
app:layout_behavior="@string/appbar_scrolling_view_behavior"  />
</android.support.design.widget.CoordinatorLayout>

和FragmentOne.java代码

package pk.com.sabsons.tablayout;

import android.os.Bundle;
import android.support.annotation.Nullable;
import android.support.v4.app.Fragment;
import android.util.Log;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.support.v7.widget.LinearLayoutManager;
import android.support.v7.widget.RecyclerView;
import android.view.Menu;
import android.view.MenuInflater;
import android.widget.Toast;

import com.android.volley.RequestQueue;
import com.android.volley.Response;
import com.android.volley.VolleyError;
import com.android.volley.toolbox.JsonArrayRequest;
import com.android.volley.toolbox.Volley;
import pk.com.sabsons.tablayout.R;
import pk.com.sabsons.tablayout.adpater.RvAdapter;
import pk.com.sabsons.tablayout.model.Anime;

import org.json.JSONArray;
import org.json.JSONException;
import org.json.JSONObject;

import java.util.ArrayList;
import java.util.List;
import pk.com.sabsons.tablayout.R;

public class OneFragment extends Fragment {

View view;
private List<Anime> lstAnime ;
private RecyclerView myrv;
private RvAdapter rvadapter;
//https://awsrh.blogspot.com/2018/03/volley-glide-tutorial-parse-json.html
   private String URL_JSON =                 
  "https://gist.githubusercontent.com/aws1994/
  f583d54e5af8e56173492d3f60dd5ebf/raw/    
  c7796ba51d5a0d37fc756cf0fd14e54434c547bc/anime.json";

 private JsonArrayRequest ArrayRequest;
 private RequestQueue requestQueue;
private RecyclerView.LayoutManager mLayoutManager;
private LinearLayoutManager mLinerLayoutManager;

public void OneFragment() {

}


@Override
public void onCreate(@Nullable Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    lstAnime = new ArrayList<>();
    jsoncall();

    rvadapter.registerAdapterDataObserver(new 
    RecyclerView.AdapterDataObserver() {
        @Override
        public void onItemRangeChanged(int positionStart, int itemCount) {
            super.onItemRangeInserted(positionStart, itemCount);
            int friendlyMessageCount = rvadapter.getItemCount();
            int lastVisiblePosition =
                    mLinerLayoutManager.findLastVisibleItemPosition();
            if (lastVisiblePosition == -1 ||
                    (positionStart >= (friendlyMessageCount - 1) &&
                            lastVisiblePosition == (positionStart - 1))) {
                myrv.scrollToPosition(positionStart);
            }
        }
    });
    myrv.setAdapter(rvadapter);
}

@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle 
savedInstanceState) {
    view = inflater.inflate(R.layout.fragment_one, container, false);
    myrv = (RecyclerView) view.findViewById(R.id.rv);
    RvAdapter recyleradpater = new RvAdapter(getContext(),lstAnime);
    myrv.setLayoutManager(new LinearLayoutManager(getActivity()));
    myrv.setAdapter(recyleradpater);
    return view;




}
public void jsoncall() {


    ArrayRequest = new JsonArrayRequest(URL_JSON, new 
Response.Listener<JSONArray>() {
        @Override
        public void onResponse(JSONArray response) {

            JSONObject jsonObject = null;


            for (int i = 0 ; i<response.length();i++) {



                try {

                    jsonObject = response.getJSONObject(i);
                    Anime anime = new Anime();

                    anime.setName(jsonObject.getString("name"));
                    anime.setRating(jsonObject.getString("category"));

   anime.setDescription(jsonObject.getString("description"));
                    anime.setImage_url(jsonObject.getString("image"));
                    anime.setStudio(jsonObject.getString("category"));
                    anime.setCategorie(jsonObject.getString("category"));

                    lstAnime.add(anime);
                }
                catch (JSONException e) {
                    e.printStackTrace();
                }
            }






        }
    }, new Response.ErrorListener() {
        @Override
        public void onErrorResponse(VolleyError error) {

        }
    });


    requestQueue = Volley.newRequestQueue(getActivity());
    requestQueue.add(ArrayRequest);
}
}

和 FragmentOne.xml

<RelativeLayout
android:background="#fafafa"
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context="pk.com.sabsons.tablayout.OneFragment"
>

<android.support.v7.widget.RecyclerView
    android:layout_marginRight="20dp"
    android:layout_marginLeft="20dp"
    android:id="@+id/rv"
    android:layout_marginTop="20dp"
    android:layout_width="match_parent"
    android:layout_height="match_parent">

</android.support.v7.widget.RecyclerView>

MyAdapter 代码是:

package pk.com.sabsons.tablayout.adpater;
import android.content.Context;
import android.content.Intent;
import android.support.v7.widget.RecyclerView;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ImageView;
import android.widget.TextView;

import com.bumptech.glide.Glide;
import com.bumptech.glide.request.RequestOptions;
import pk.com.sabsons.tablayout.OneFragment;
import pk.com.sabsons.tablayout.model.Anime;
import pk.com.sabsons.tablayout.R;
import java.util.List;

public class RvAdapter extends RecyclerView.Adapter<RvAdapter.MyViewHolder> {
RequestOptions options ;
private Context mContext ;
private List<Anime> mData ;


public RvAdapter(Context mContext, List lst) {


    this.mContext = mContext;
    this.mData = lst;
    options = new RequestOptions()
            .centerCrop()
            .placeholder(R.drawable.loading)
            .error(R.drawable.loading);

}

@Override
public MyViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {

    View view ;
    LayoutInflater mInflater = LayoutInflater.from(mContext);
    view = mInflater.inflate(R.layout.anime_item_row,parent,false);
    // click listener here
    return new MyViewHolder(view);
}

@Override
public void onBindViewHolder(MyViewHolder holder, final int position) {

    holder.tvname.setText(mData.get(position).getName());
    holder.tv_rate.setText(mData.get(position).getRating());
    holder.tvstudio.setText(mData.get(position).getStudio());
    holder.tvcat.setText(mData.get(position).getCategorie());

    // load image from the internet using Glide
        Glide.with(mContext).load(mData.get(position)
    .getImage_url()).apply(options).into(holder.AnimeThumbnail);

}

@Override
public int getItemCount() {
    return mData.size();
}

public static class MyViewHolder extends RecyclerView.ViewHolder {

    TextView tvname,tv_rate,tvstudio,tvcat;
    ImageView AnimeThumbnail;


    public MyViewHolder(View itemView) {
        super(itemView);
        tvname = itemView.findViewById(R.id.rowname);
        tvstudio = itemView.findViewById(R.id.studio);
        tv_rate = itemView.findViewById(R.id.rating);
        tvcat = itemView.findViewById(R.id.categorie);
        AnimeThumbnail = itemView.findViewById(R.id.thumbnail);
    }
        }
        }

请帮助我哪里做错了。数据已正确加载，但在我在 fragment 之间滚动后会显示 recyclerview，或者如果打开键盘则它会显示在所有 fragment 中。

Answer 1

在您的 lstAnime 中添加数据后，您只是忘记通知您的 recyleradpater> 列表

在 lstAnime 列表中添加数据后，只需使用 recyleradpater.notifyDataSetChanged();

示例代码

public void jsoncall() {


    ArrayRequest = new JsonArrayRequest(URL_JSON, new 
Response.Listener<JSONArray>() {
        @Override
        public void onResponse(JSONArray response) {

            JSONObject jsonObject = null;


            for (int i = 0 ; i<response.length();i++) {



                try {

                    jsonObject = response.getJSONObject(i);
                    Anime anime = new Anime();

                    anime.setName(jsonObject.getString("name"));
                    anime.setRating(jsonObject.getString("category"));

   anime.setDescription(jsonObject.getString("description"));
                    anime.setImage_url(jsonObject.getString("image"));
                    anime.setStudio(jsonObject.getString("category"));
                    anime.setCategorie(jsonObject.getString("category"));

                    lstAnime.add(anime);
                }

                catch (JSONException e) {
                    e.printStackTrace();
                }
            }
            recyleradpater.notifyDataSetChanged();





        }
    }, new Response.ErrorListener() {
        @Override
        public void onErrorResponse(VolleyError error) {

        }
    });


    requestQueue = Volley.newRequestQueue(getActivity());
    requestQueue.add(ArrayRequest);
}