Question

我收到此错误。

03-22 11：41：20.439 20933-20933 / com.androidcss.jsonexample E / RecyclerView：没有连接适配器;跳过布局 03-22 11：41：20.760 20933-20933 / com.androidcss.jsonexample W / art：在Android 4.1之前，方法int android.support.v7.widget.ListViewCompat.lookForSelectablePosition（int，boolean）会错误地覆盖包 - android.widget.ListView中的私有方法

MainActivity.java

package com.androidcss.jsonexample;

import android.app.ProgressDialog;
import android.os.AsyncTask;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.support.v7.widget.LinearLayoutManager;
import android.support.v7.widget.RecyclerView;
import android.widget.Toast;
import org.json.JSONArray;
import org.json.JSONException;
import org.json.JSONObject;
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.net.HttpURLConnection;
import java.net.MalformedURLException;
import java.net.URL;
import java.util.ArrayList;
import java.util.List;

public class MainActivity extends AppCompatActivity {

    // CONNECTION_TIMEOUT and READ_TIMEOUT are in milliseconds
    public static final int CONNECTION_TIMEOUT = 10000;
    public static final int READ_TIMEOUT = 15000;
    private RecyclerView mRVFishPrice;
    private AdapterFish mAdapter;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        //Make call to AsyncTask
        new AsyncLogin().execute();


    }

    private class AsyncLogin extends AsyncTask<String, String, String> {
        ProgressDialog pdLoading = new ProgressDialog(MainActivity.this);
        HttpURLConnection conn;
        URL url = null;

        @Override
        protected void onPreExecute() {
            super.onPreExecute();

            //this method will be running on UI thread
            pdLoading.setMessage("\tLoading...");
            pdLoading.setCancelable(false);
            pdLoading.show();

        }

        @Override
        protected String doInBackground(String... params) {
            try {

                // Enter URL address where your json file resides
                // Even you can make call to php file which returns json data
                url = new URL("https://newsapi.org/v1/articles?source=the-next-web&sortBy=latest&apiKey=bdba5de1b490495796a1595f77ed3f37");

            } catch (MalformedURLException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
                return e.toString();
            }
            try {

                // Setup HttpURLConnection class to send and receive data from php and mysql
                conn = (HttpURLConnection) url.openConnection();
                conn.setReadTimeout(READ_TIMEOUT);
                conn.setConnectTimeout(CONNECTION_TIMEOUT);
                conn.setRequestMethod("GET");

                // setDoOutput to true as we recieve data from json file
                conn.setDoOutput(true);

            } catch (IOException e1) {
                // TODO Auto-generated catch block
                e1.printStackTrace();
                return e1.toString();
            }

            try {

                int response_code = conn.getResponseCode();

                // Check if successful connection made
                if (response_code == HttpURLConnection.HTTP_OK) {

                    // Read data sent from server
                    InputStream input = conn.getInputStream();
                    BufferedReader reader = new BufferedReader(new InputStreamReader(input));
                    StringBuilder result = new StringBuilder();
                    String line;

                    while ((line = reader.readLine()) != null) {
                        result.append(line);
                    }

                    // Pass data to onPostExecute method
                    return (result.toString());

                } else {

                    return ("unsuccessful");
                }

            } catch (IOException e) {
                e.printStackTrace();
                return e.toString();
            } finally {
                conn.disconnect();
            }


        }

        @Override
        protected void onPostExecute(String result) {

            //this method will be running on UI thread

            pdLoading.dismiss();
            List<Item> data=new ArrayList<>();

            pdLoading.dismiss();
            try {

                JSONObject object= new JSONObject(result);
                JSONArray array = object.getJSONArray("articles");

                // Extract data from json and store into ArrayList as class objects
                for(int i=0;i<array.length();i++){
                    JSONObject json_data = array.getJSONObject(i);
                    Item item= new Item();
                    item.name= json_data.getString("title");

                    data.add(item);
                }

                // Setup and Handover data to recyclerview
                mRVFishPrice = (RecyclerView)findViewById(R.id.fishPriceList);
                mAdapter = new AdapterFish(MainActivity.this, data);
                mRVFishPrice.setAdapter(mAdapter);
                mRVFishPrice.setLayoutManager(new LinearLayoutManager(MainActivity.this));

            } catch (JSONException e) {
                Toast.makeText(MainActivity.this, e.toString(), Toast.LENGTH_LONG).show();
            }

        }

    }
}

AdapterFish.java

package com.androidcss.jsonexample;

import android.content.Context;
import android.support.v4.content.ContextCompat;
import android.support.v7.widget.RecyclerView;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.TextView;
import com.bumptech.glide.Glide;
import java.util.Collections;
import java.util.List;

public class AdapterFish extends RecyclerView.Adapter<RecyclerView.ViewHolder> {

    private Context context;
    private LayoutInflater inflater;
    List<Item> data= Collections.emptyList();
    Item current;
    int currentPos=0;

    // create constructor to innitilize context and data sent from MainActivity
    public AdapterFish(Context context, List<Item> data){
        this.context=context;
        inflater= LayoutInflater.from(context);
        this.data=data;
    }

    // Inflate the layout when viewholder created
    @Override
    public RecyclerView.ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
        View view=inflater.inflate(R.layout.card, parent,false);
        MyHolder holder=new MyHolder(view);
        return holder;
    }

    // Bind data
    @Override
    public void onBindViewHolder(RecyclerView.ViewHolder holder, int position) {

        // Get current position of item in recyclerview to bind data and assign values from list
        MyHolder myHolder= (MyHolder) holder;
        Item current=data.get(position);

        myHolder.name.setText(current.getName());

        // load image into imageview using glide
        /*Glide.with(context).load("http://192.168.1.7/test/images/" + current.fishImage)
                .placeholder(R.drawable.ic_img_error)
                .error(R.drawable.ic_img_error)
                .into(myHolder.ivFish);*/

    }

    // return total item from List
    @Override
    public int getItemCount() {
        return data.size();
    }


    class MyHolder extends RecyclerView.ViewHolder{

        TextView name;


        // create constructor to get widget reference
        public MyHolder(View itemView) {
            super(itemView);
            name = (TextView)itemView.findViewById(R.id.name);


        }

    }

}

Item.java

package com.androidcss.jsonexample;

public class Item {

    String name;

    public String getName() {
        return name;
    }
}

Answer 1

setLayoutManager之前需要setAdapter。

Answer 2

您正在初始化RecyclerView中的AsynTask，这意味着您的ReyclerView在创建视图时尚未就绪。

进行以下更改。

//make list as global variable
private List<Item> data;
@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);

    //view should be initialized in UI thread
    data=new ArrayList<>();
    mRVFishPrice = (RecyclerView)findViewById(R.id.fishPriceList);
    mAdapter = new AdapterFish(MainActivity.this, data);
    mRVFishPrice.setLayoutManager(new LinearLayoutManager(MainActivity.this));
    mRVFishPrice.setAdapter(mAdapter);

    //Make call to AsyncTask
    new AsyncLogin().execute();
}

然后在您的onPostExecute

中

替换 -

mRVFishPrice = (RecyclerView)findViewById(R.id.fishPriceList);
mAdapter = new AdapterFish(MainActivity.this, data);
mRVFishPrice.setAdapter(mAdapter);
mRVFishPrice.setLayoutManager(new LinearLayoutManager(MainActivity.this));

与

mAdapter.notifyDatasetChanged();

并确保从postexecute中删除List<Item> data并将其设为全局

请使用Volley进行API调用，而不是实现Custom 背景任务。 Volley异步处理API调用弄乱你的实际代码。

Answer 3

我遇到了同样的问题。问题出在布局上。如果您的视图和布局的顺序正确，则应首先验证。

错误地覆盖包

3 个答案: