Question

实际上标题描述了我的问题。我正在为recyclerView设置适配器，但问题仍然存在。我认为我调用方法来设置适配器的地方不是问题而是事实......（或者可能不是问题）。

设置适配器的方法是showData（）;

修改没有错误（THX Rohit Arya），但我仍然看不到照片（有空白页）。

代码：

MainFragment类：

node_modules

BoardAdapter类：

package com.sarusi.amit.smarts;

import android.support.v4.app.Fragment;
import android.app.ProgressDialog;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.os.AsyncTask;
import android.os.Bundle;
import android.support.v7.widget.LinearLayoutManager;
import android.support.v7.widget.RecyclerView;
import android.util.Base64;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;

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

import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.net.HttpURLConnection;
import java.net.URL;

/**
 * A simple {@link Fragment} subclass.
 */
public class MainFragment extends Fragment {

    private RecyclerView recyclerView;
    private RecyclerView.LayoutManager manager;
    private RecyclerView.Adapter adapter;
    private APIConfig apiConfig;

    public MainFragment() {
        // Required empty public constructor
    }

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

        APIConfig.names = new String[1];
        APIConfig.bitmaps = new Bitmap[1];

        recyclerView = (RecyclerView) view.findViewById(R.id.fragment_main_recyclerView);
        recyclerView.setHasFixedSize(true);

        manager = new LinearLayoutManager(getContext());

        recyclerView.setLayoutManager(manager);

        adapter = new BoardAdapter(APIConfig.names, APIConfig.bitmaps);
        recyclerView.setAdapter(adapter);

        getBoardsData();

        return view;
    }

    private void getBoardsData() {

        class ConnectionTask extends AsyncTask<String, Void, String> {
            ProgressDialog progressDialog;

            @Override
            protected void onPreExecute() {
                progressDialog = ProgressDialog.show(getContext(), "Fetching Data...", "A Trap", false, false);
                super.onPreExecute();
            }

            @Override
            protected void onPostExecute(String s) {
                super.onPostExecute(s);
                progressDialog.dismiss();
                parseJSON(s);
                showData();
                adapter.notifyDataSetChanged();

            }

            @Override
            protected String doInBackground(String... params) {
                BufferedReader bufferedReader;
                try {
                    URL url = new URL(apiConfig.IMAGES_URL);
                    HttpURLConnection con = (HttpURLConnection) url.openConnection();
                    StringBuilder sb = new StringBuilder();

                    bufferedReader = new BufferedReader(new InputStreamReader(con.getInputStream()));

                    String json;
                    while ((json = bufferedReader.readLine()) != null) {
                        sb.append(json + "\n");
                    }

                    return sb.toString().trim();

                } catch (Exception e) {
                    return null;
                }
            }
        }

        ConnectionTask connectionTask = new ConnectionTask();
        connectionTask.execute();

    }

    public void showData () {
        adapter = new BoardAdapter(APIConfig.names, APIConfig.bitmaps);
        recyclerView.setAdapter(adapter);
    }


    private void parseJSON(String json) {
        try {
            JSONObject jsonObject = new JSONObject(json);
            JSONArray jsonArray = jsonObject.getJSONArray(apiConfig.TAG_JSON_ARRAY);

            apiConfig = new APIConfig(jsonArray.length());

            for (int i = 0; i < jsonArray.length(); i++) {
                JSONObject JSO = jsonArray.getJSONObject(i);
                APIConfig.names[i] = JSO.getString(apiConfig.TAG_NAME);
                APIConfig.bitmaps[i] = base64ToBitmap(JSO.getString(apiConfig.TAG_IMAGE));
            }

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

    }

    private Bitmap base64ToBitmap(String b64) {
        byte[] imageAsBytes = Base64.decode(b64.getBytes(), Base64.DEFAULT);
        return BitmapFactory.decodeByteArray(imageAsBytes, 0, imageAsBytes.length);
    }
}

fragment_main：

package com.sarusi.amit.smarts;

import android.content.Context;
import android.graphics.Bitmap;
import android.support.v7.widget.RecyclerView;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ArrayAdapter;
import android.widget.ImageView;
import android.widget.TextView;

import java.util.ArrayList;
import java.util.List;

/**
 * Created by amit on 3/21/16.
 */
public class BoardAdapter extends RecyclerView.Adapter<BoardAdapter.ViewHolder> {

    List<Board> boards;

    public BoardAdapter(String[] names, Bitmap[] images) {
        super();
        boards = new ArrayList<>();
        for (int i = 0; i < names.length; i++) {
            Board board = new Board();
            board.setImage(images[i]);
            board.setName(names[i]);
            boards.add(board);
        }
    }

    @Override
    public ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
        View view = LayoutInflater.from(parent.getContext()).inflate(R.layout.board_row, parent, false);
        ViewHolder viewHolder = new ViewHolder(view);
        return viewHolder;
    }

    @Override
    public void onBindViewHolder(ViewHolder holder, int position) {
        Board board = boards.get(position);
        holder.imageView.setImageBitmap(board.getImage());
        holder.name.setText(board.getName());
    }

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


    //The class for the viewHolder
    class ViewHolder extends RecyclerView.ViewHolder {

        public ImageView imageView;
        public TextView name;

        public ViewHolder(View itemView) {
            super(itemView);
            this.imageView = (ImageView) itemView.findViewById(R.id.board_row_image);
            this.name = (TextView) itemView.findViewById(R.id.board_row_name);
        }
    }
}

board_row：

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical"
    tools:context="com.sarusi.amit.smarts.MainFragment">

    <android.support.v7.widget.RecyclerView
        android:id="@+id/fragment_main_recyclerView"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content">

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

</LinearLayout>

Answer 1

有一段时间RecyclerView没有适配器到达。您可以在使用空列表初始化RecyclerView时设置适配器，然后在收到数据后，更新列表并调用适配器的notifyDataSetChanged。

Answer 2

在onCreateView：

manager = new LinearLayoutManager(getContext());

recyclerView.setLayoutManager(manager);

adapter = new BoardAdapter(APIConfig.names, APIConfig.bitmaps);
recyclerView.setAdapter(adapter);

此处，APIConfig.names和APIConfig.bitmaps将为空（不 null）。

更新onPostExecute的这些值AsyncTask并在适配器上调用notifyDataSetChanged。

没有适配器;使用RecyclerView跳过布局

2 个答案: