运行 recyclerView 程序出现白屏问题

Question

我正在尝试制作一个将显示数据编程到 recyclerView 中的程序。我的程序有问题，当我尝试在 recyclerView 中显示数据时，屏幕显示为白色，没有任何显示。如果有人知道代码有什么问题，请帮助我。附上我项目的完整代码。还附上全Logcat.

从一个页面开始 MainActivity


public class MainActivity extends AppCompatActivity {
    private static final String HI = "https://uniqueandrocode.000webhostapp.com/hiren/androidtutorial/getimagelikedata.php";
    private List<MyListData>myListData;
    private RecyclerView rv;
    private JsonArrayRequest request;
    private RequestQueue requestQueue;
    private MyAdapter adapter;
    public static MyDatabase myDatabase;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        rv=(RecyclerView)findViewById(R.id.recycler_view);
        rv.setHasFixedSize(true);
        rv.setLayoutManager(new LinearLayoutManager(this));

        myListData=new ArrayList();
        myDatabase= Room.databaseBuilder(getApplicationContext(),MyDatabase.class,"mydb").allowMainThreadQueries().build();
       getData();
    }

    private void getData() {
        request=new JsonArrayRequest(HI, new Response.Listener<JSONArray>() {
            @Override
            public void onResponse(JSONArray response) {
                JSONObject jsonObject=null;
                for (int i=0; i<response.length(); i++){
                    try {
                        JSONObject ob=response.getJSONObject(i);
                        MyListData md=new MyListData(ob.getInt("id"),ob.getString("imageurl"),ob.getString("like"));
                        myListData.add(md);
                    } catch (JSONException e) {
                        e.printStackTrace();
                    }

                }
                setupData(myListData);

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

            }
        });

        requestQueue= Volley.newRequestQueue(this);
        requestQueue.add(request);

    }

    private void setupData(List<MyListData> myListData) {


        adapter=new MyAdapter( myListData,this);
        rv.setAdapter(adapter);


    }
}

class MyAdapter

public class MyAdapter extends RecyclerView.Adapter<MyAdapter.ViewHolder> {
private static final String PO ="https://uniqueandrocode.000webhostapp.com/hiren/androidtutorial/dislikedata.php?id=" ;
private static final String DE="https://uniqueandrocode.000webhostapp.com/hiren/androidtutorial/likedata.php?id=";
private List<MyListData>myListData;
private Context ct;
private JsonArrayRequest request,request1;
private RequestQueue requestQueue,rq;

public MyAdapter(List<MyListData> myListData, Context ct) {
        this.myListData = myListData;
        this.ct = ct;
        }

@NonNull
@Override
public ViewHolder onCreateViewHolder(@NonNull ViewGroup viewGroup, int i) {
        View view=LayoutInflater.from(viewGroup.getContext()).inflate(R.layout.list_data,viewGroup,false);
        return new ViewHolder(view);
        }

@Override
public void onBindViewHolder(@NonNull final ViewHolder viewHolder, final int i) {
final MyListData mk=myListData.get(i);
        Picasso.with(ct)
        .load(mk.getImageurl())
        .into(viewHolder.img);
        viewHolder.likecount.setText(mk.getLikecount());
        if (MainActivity.myDatabase.myDao().isLiked(mk.getId())==1)
        viewHolder.likebtn.setImageResource(R.drawable.ic_launcher_background);
        else
        viewHolder.likebtn.setImageResource(R.drawable.ic_launcher_background);

        viewHolder.likebtn.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
        LikeDislike_List mt=new LikeDislike_List();
        //String uid=mk.getId();
        int id=mk.getId();
        String imp=mk.getImageurl();
        mt.setId(id);
        mt.setName(imp);

        if (MainActivity.myDatabase.myDao().isLiked(id)!=1){
        viewHolder.likebtn.setImageResource(R.drawable.ic_launcher_background);
        MainActivity.myDatabase.myDao().addData(mt);

        String mo=mk.getLikecount();
        viewHolder.likecount.setText(mo);

        delieteLike(id,viewHolder);


        }else {
        MainActivity.myDatabase.myDao().delete(mt);
        viewHolder.likebtn.setImageResource(R.drawable.ic_launcher_background);
        String mo=mk.getLikecount();

        addLike(id,viewHolder);

        }


        }
        });
        }

private void addLike(final int id, final ViewHolder viewHolder) {
        request=new JsonArrayRequest(PO + id, new Response.Listener<JSONArray>() {
@Override
public void onResponse(JSONArray response) {
        JSONObject jsonObject=null;

        for (int i=0; i <response.length(); i++){
        try {
        JSONObject object=response.getJSONObject(i);
        String like=object.getString("like");
        viewHolder.likecount.setText(like);
        } catch (JSONException e) {
        e.printStackTrace();
        }
        }
        }
        }, new Response.ErrorListener() {
@Override
public void onErrorResponse(VolleyError error) {

        }
        });
        requestQueue= Volley.newRequestQueue(ct);
        requestQueue.add(request);


        }

private void delieteLike(final int id, final ViewHolder viewHolder) {
        request1 =new JsonArrayRequest(DE + id, new Response.Listener<JSONArray>() {
@Override
public void onResponse(JSONArray response) {
        JSONObject jsonObject=null;
        for (int i=0; i<response.length(); i++){
        try {
        JSONObject object=response.getJSONObject(i);
        String like=object.getString("like");
        viewHolder.likecount.setText(like);
        } catch (JSONException e) {
        e.printStackTrace();
        }
        }
        }
        }, new Response.ErrorListener() {
@Override
public void onErrorResponse(VolleyError error) {

        }
        });
        rq=Volley.newRequestQueue(ct);
        rq.add(request1);

        }

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

public class ViewHolder extends RecyclerView.ViewHolder{
    private ImageView img,likebtn;
    private TextView likecount;
    public ViewHolder(@NonNull View itemView) {
        super(itemView);
        img=(ImageView)itemView.findViewById(R.id.imageview);
        likebtn=(ImageView)itemView.findViewById(R.id.like_btn);
        likecount=(TextView)itemView.findViewById(R.id.like_count);
    }
}
}

public class MyListData {
   private int id;
   private String imageurl;
   private String likecount;

   public MyListData(int id, String imageurl, String likecount) {
       this.id = id;
       this.imageurl = imageurl;
       this.likecount = likecount;
   }

   public int getId() {
       return id;
   }

   public String getImageurl() {
       return imageurl;
   }

   public String getLikecount() {
       return likecount;
   }
}

import androidx.room.Database;
import androidx.room.RoomDatabase;

@Database(entities={LikeDislike_List.class},version = 1, exportSchema = false)
public abstract class MyDatabase extends RoomDatabase  {
    public abstract LikeDislikeDao myDao();
}

package com.example.myapplication;



import androidx.room.ColumnInfo;
import androidx.room.Entity;
import androidx.room.PrimaryKey;

@Entity(tableName="mydata")
public class LikeDislike_List {
    @PrimaryKey
    private int id;
    @ColumnInfo(name = "user_name")
    private String name;

    public int getId() {
        return id;
    }

    public void setId(int id) {
        this.id = id;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }
}

@Dao
public interface LikeDislikeDao {
   @Insert
   public void addData(LikeDislike_List likeDislikeList);

   @Query("select * from mydata")
   public List<LikeDislike_List>getMyData();

   @Query("SELECT EXISTS (SELECT 1 FROM mydata WHERE id=:id)")
   public int isLiked(int id);

   @Delete
   public void delete(LikeDislike_List likeDislikeList);


}

Logcat

02-17 19:04:01.856 7156-7161/? E/jdwp: Failed writing handshake bytes: Broken pipe (-1 of 14)
02-17 19:04:02.276 7156-7156/? E/dalvikvm: Could not find class 'androidx.core.view.ViewCompat', referenced from method androidx.core.view.ViewCompat.addOnUnhandledKeyEventListener
02-17 19:04:02.280 7156-7156/? E/dalvikvm: Could not find class 'android.view.WindowInsets', referenced from method androidx.core.view.ViewCompat.dispatchApplyWindowInsets
02-17 19:04:02.364 7156-7156/? E/dalvikvm: Could not find class 'android.view.WindowInsets', referenced from method androidx.core.view.ViewCompat.onApplyWindowInsets
02-17 19:04:02.364 7156-7156/? E/dalvikvm: Could not find class 'android.view.View$OnUnhandledKeyEventListener', referenced from method androidx.core.view.ViewCompat.removeOnUnhandledKeyEventListener
02-17 19:04:02.368 7156-7156/? E/dalvikvm: Could not find class 'androidx.core.view.ViewCompat', referenced from method androidx.core.view.ViewCompat.setOnApplyWindowInsetsListener
02-17 19:04:02.636 7156-7156/? E/dalvikvm: Could not find class 'android.graphics.drawable.RippleDrawable', referenced from method androidx.appcompat.widget.AppCompatImageHelper.hasOverlappingRendering
02-17 19:04:02.824 7156-7156/? E/dalvikvm: Could not find class 'android.view.textclassifier.TextClassificationManager', referenced from method androidx.appcompat.widget.AppCompatTextClassifierHelper.getTextClassifier
02-17 19:04:03.044 7156-7156/com.example.myapplication E/RecyclerView: No adapter attached; skipping layout
02-17 19:04:03.060 7156-7156/com.example.myapplication E/RecyclerView: No adapter attached; skipping layout

Answer 1

先生，您错过了定义 GET 请求的第三个参数

  private void getData() {
    request=new JsonArrayRequest(HI, Request.Method.GET,
 new Response.Listener<JSONArray>() {
        @Override
        public void onResponse(JSONArray response) {
            JSONObject jsonObject=null;
            for (int i=0; i<response.length(); i++){
                try {
                    JSONObject ob=response.getJSONObject(i);
                    MyListData md=new MyListData(ob.getInt("id"),ob.getString("imageurl"),ob.getString("like"));
                    myListData.add(md);
                } catch (JSONException e) {
                    e.printStackTrace();
                }

            }
            setupData(myListData);

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

        }
    });

    requestQueue= Volley.newRequestQueue(this);
    requestQueue.add(request);

}

运行 recyclerView 程序出现白屏问题

problem white screen with running the program of recyclerView

java

android

android-volley

android-recyclerview