Android端API数据加载异常：RecyclerView无法显示电影列表求助

问题概述 #

我正在使用Java开发一款原生Android电影应用，通过API获取印度高分电影数据并展示，但屏幕上的RecyclerView无法显示数据。目标UI为左侧电影海报、右侧电影名称及上映年份的列表布局。

相关代码 #

MainActivity.java #

public class MainActivity extends AppCompatActivity {
    private static String JSON_URL="https://raw.githubusercontent.com/FEND16/movie-json-data/master/json/top-rated-indian-movies-01.json";

    List<MovieModelClass> movieList;
    RecyclerView recyclerView;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        movieList=new ArrayList<>();
        recyclerView=findViewById(R.id.recyclerView);

        // 创建异步任务
        GetData getData=new GetData();
        getData.execute();
    }
    public class GetData extends AsyncTask<String,String,String>{


        @Override
        protected String doInBackground(String... strings) {
            String current="";
            try{
                URL url;
                HttpURLConnection urlConnection=null;
                try{
                    url=new URL(JSON_URL);
                    urlConnection=(HttpURLConnection) url.openConnection();

                    InputStream is=urlConnection.getInputStream();
                    InputStreamReader isr=new InputStreamReader(is);
                    int data=isr.read();
                    while (data!=-1)
                    {
                        current+=(char)data;
                        data=isr.read();
                        return current;
                    }
                } catch (MalformedURLException e) {
                    e.printStackTrace();
                } catch (IOException e) {
                    e.printStackTrace();
                }finally {
                    if(urlConnection!=null)
                    {
                        urlConnection.disconnect();
                    }
                }
            } catch (Exception e) {
                e.printStackTrace();
            }
            return current;
        }

        @Override
        protected void onPostExecute(String s) {
            try {
                JSONArray jsonArray=new JSONArray(s);
                for(int i=0;i<jsonArray.length();++i)
                {
                    JSONObject jsonObject1=jsonArray.getJSONObject(i);

                    MovieModelClass model=new MovieModelClass();
                    model.setName(jsonObject1.getString("title"));
                    model.setReleaseDate(jsonObject1.getString("year"));
                    model.setImg(jsonObject1.getString("poster"));

                    movieList.add(model);
                }
            } catch (JSONException e) {
                e.printStackTrace();
            }
            PutDataIntoRecyclerView(movieList);
        }
    }
    private void PutDataIntoRecyclerView(List<MovieModelClass> movieList){
        Adaptery adaptery =new Adaptery(this,movieList);
        recyclerView.setLayoutManager(new LinearLayoutManager(this));
        recyclerView.setAdapter(adaptery);
    }
}

Adaptery.java #

package patil.rohan.movieapplication;

import android.content.Context;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ImageView;
import android.widget.TextView;

import androidx.annotation.NonNull;
import androidx.recyclerview.widget.RecyclerView;

import com.bumptech.glide.Glide;

import java.util.List;

public class Adaptery extends RecyclerView.Adapter<Adaptery.MyViewHolder> {
    private Context mContext;
    private List<MovieModelClass> mData;

    public Adaptery(Context mContext, List<MovieModelClass> mData) {
        this.mContext = mContext;
        this.mData = mData;
    }

    @NonNull
    @Override
    public MyViewHolder onCreateViewHolder(@NonNull ViewGroup parent, int viewType) {
        View v;
        LayoutInflater inflater=LayoutInflater.from(mContext);
        v=inflater.inflate(R.layout.movie_item,parent,false);
        return new MyViewHolder(v);
    }

    @Override
    public void onBindViewHolder(@NonNull MyViewHolder holder, int position) {
        holder.name.setText(mData.get(position).getName());
        holder.release.setText(mData.get(position).getReleaseDate());
        Glide.with(mContext).load(mData.get(position).getImg()).into(holder.img);
    }

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


    public static class MyViewHolder extends RecyclerView.ViewHolder{
        TextView name;
        TextView release;
        ImageView img;
        public MyViewHolder(@NonNull View itemView) {
            super(itemView);
            name=itemView.findViewById(R.id.name_txt);
            release=itemView.findViewById(R.id.release_txt);
            img=itemView.findViewById(R.id.imageView);

        }
    }
}

MovieModelClass.java #

package patil.rohan.movieapplication;

public class MovieModelClass {
    String name;
    String releaseDate;
    String img;

    public MovieModelClass() {
    }

    public MovieModelClass(String name, String releaseDate, String img) {
        this.name = name;
        this.releaseDate = releaseDate;
        this.img = img;
    }

    public String getName() {
        return name;
    }

    public String getReleaseDate() {
        return releaseDate;
    }

    public String getImg() {
        return img;
    }

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

    public void setReleaseDate(String releaseDate) {
        this.releaseDate = releaseDate;
    }

    public void setImg(String img) {
        this.img = img;
    }
}

movie_item.xml #

<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout 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="wrap_content">

    <TextView
        android:id="@+id/name_txt"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginTop="44dp"
        android:layout_marginEnd="48dp"
        android:fontFamily="sans-serif-black"
        android:text="TextView"
        android:textSize="32sp"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintHorizontal_bias="0.809"
        app:layout_constraintStart_toEndOf="@+id/imageView"
        app:layout_constraintTop_toTopOf="parent" />

    <TextView
        android:id="@+id/release_txt"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="TextView"
        android:textSize="18sp"
        app:layout_constraintEnd_toEndOf="@+id/name_txt"
        app:layout_constraintHorizontal_bias="0.0"
        app:layout_constraintStart_toStartOf="@+id/name_txt"
        tools:layout_editor_absoluteY="95dp" />

    <ImageView
        android:id="@+id/imageView"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginStart="16dp"
        android:layout_marginTop="16dp"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent"
        tools:srcCompat="@tools:sample/avatars" />
</androidx.constraintlayout.widget.ConstraintLayout>

问题排查与修复方案 #

1. AsyncTask数据读取逻辑错误 #

在GetData类的doInBackground方法中，while循环内的return current语句会导致读取第一个字符后就立即返回，无法完整获取JSON数据。

修复代码：
将return current移出while循环：

@Override
protected String doInBackground(String... strings) {
    String current="";
    try{
        URL url;
        HttpURLConnection urlConnection=null;
        try{
            url=new URL(JSON_URL);
            urlConnection=(HttpURLConnection) url.openConnection();

            InputStream is=urlConnection.getInputStream();
            InputStreamReader isr=new InputStreamReader(is);
            int data=isr.read();
            while (data!=-1)
            {
                current+=(char)data;
                data=isr.read();
            }
            // 移到循环外
            return current;
        } catch (MalformedURLException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }finally {
            if(urlConnection!=null)
            {
                urlConnection.disconnect();
            }
        }
    } catch (Exception e) {
        e.printStackTrace();
    }
    return current;
}

2. 布局约束问题 #

release_txt的垂直约束使用了tools:layout_editor_absoluteY，该属性仅在布局编辑器中生效，运行时会导致TextView位置异常，可能被遮挡或超出列表项范围。

修复代码：
修改movie_item.xml中release_txt的约束，将其与name_txt关联：

<TextView
    android:id="@+id/release_txt"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:text="TextView"
    android:textSize="18sp"
    app:layout_constraintEnd_toEndOf="@+id/name_txt"
    app:layout_constraintHorizontal_bias="0.0"
    app:layout_constraintStart_toStartOf="@+id/name_txt"
    app:layout_constraintTop_toBottomOf="@+id/name_txt"
    android:layout_marginTop="8dp"/>

3. 额外优化建议 #

• 网络请求替代方案：AsyncTask已被废弃，建议改用OkHttp或Retrofit进行网络请求，更稳定且符合现代Android开发规范。
• 图片加载依赖：确保Glide已正确添加依赖到Module级别的build.gradle：

implementation 'com.github.bumptech.glide:glide:4.16.0'
annotationProcessor 'com.github.bumptech.glide:compiler:4.16.0'

• 权限配置：在AndroidManifest.xml中添加网络权限：

<uses-permission android:name="android.permission.INTERNET"/>

内容的提问来源于stack exchange，提问作者Rohan Patil