java - 即使编译时没有错误，JSON 查询也不显示项目

Question

我刚开始学习 android，所以现在我的目标是使用 Youtube API 创建一个具有多种功能的应用程序，但其中一个功能(例如搜索视频并将其列在我的屏幕上)无法正常工作，并且没有错误，但是当我按下搜索按钮时，什么也没有发生。这是主类的代码

import androidx.appcompat.app.AppCompatActivity;

import android.os.Bundle;
import android.view.View;
import android.view.WindowManager;
import android.widget.Button;
import android.widget.EditText;
import android.widget.ImageButton;
import android.widget.ListView;
import android.widget.Toast;

import com.android.volley.Request;
import com.android.volley.RequestQueue;
import com.android.volley.Response;
import com.android.volley.VolleyError;
import com.android.volley.toolbox.StringRequest;
import com.android.volley.toolbox.Volley;
import com.app.youtubedownloader.Adapter.MyAdapter;
import com.app.youtubedownloader.Model.VideoDetails;
import com.google.android.youtube.player.YouTubeBaseActivity;

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

import java.util.ArrayList;

public class MainActivity extends AppCompatActivity {

    String API_KEY = "here is my api key";
    ListView listView;
    ArrayList<VideoDetails> videoDetailsArrayList;
    MyAdapter myadapter;
    String url = "https://www.googleapis.com/youtube/v3/search?";
    String part = "snippet";
    ImageButton searchbtn;
    EditText searchfield;
    String keySearch;
    Integer maxResults = 10;
    String order = "title";

    @Override
    protected void onCreate(Bundle savedInstanceState) {

                getWindow().setFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN,
                WindowManager.LayoutParams.FLAG_FULLSCREEN);

        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        listView = findViewById(R.id.listvideos);
        videoDetailsArrayList = new ArrayList<>();
        myadapter = new MyAdapter(MainActivity.this, videoDetailsArrayList);
        searchfield = findViewById(R.id.searchfield);
        searchbtn = findViewById(R.id.searchbtn);

        searchbtn.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                keySearch =  searchfield.getText().toString();
                displayVideos();
            }
        });





    }

    public void displayVideos(){
        RequestQueue requestQueue = Volley.newRequestQueue(getApplicationContext());

        url = "https://www.googleapis.com/youtube/v3/search?" + "part=" + part + "&q=" + keySearch + "&maxResults=3" + "&order=" + order + "&key=" + API_KEY;

        StringRequest stringRequest = new StringRequest(Request.Method.GET, url, new Response.Listener<String>() {
            @Override
            public void onResponse(String response) {

                try{
                    JSONObject jsonObject = new JSONObject(response);
                    JSONArray jsonArray = jsonObject.getJSONArray("items");

                    for(int i=0; i<jsonArray.length(); i++){
                        JSONObject jsonObject1 = jsonArray.getJSONObject(i);
                        JSONObject jsonVideoId = jsonObject1.getJSONObject("id");

                        JSONObject jsonObjectSnippet = jsonObject1.getJSONObject("snippet");

                        JSONObject jsonObjectDefault = jsonObjectSnippet.getJSONObject("thumbnails").getJSONObject("medium");

                        String video_id = jsonVideoId.getString("videoId");

                        VideoDetails vd = new VideoDetails();


                        vd.setVideoID(video_id);
                        vd.setTitle(jsonObjectSnippet.getString("title"));
                        vd.setDescription(jsonObjectSnippet.getString("description"));
                        vd.setUrl(jsonObjectDefault.getString("url"));

                        videoDetailsArrayList.add(vd);


                    }

                    listView.setAdapter(myadapter);
                    myadapter.notifyDataSetChanged();

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


            }
        }, new Response.ErrorListener() {
            @Override
            public void onErrorResponse(VolleyError error) {
                Toast.makeText(getApplicationContext(),error.getMessage(),Toast.LENGTH_LONG).show();
            }
        });


        requestQueue.add(stringRequest);


    }

}

这是适配器类

import android.app.Activity;
import android.content.Intent;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.BaseAdapter;
import android.widget.ImageView;
import android.widget.LinearLayout;
import android.widget.TextView;

import com.app.youtubedownloader.Model.VideoDetails;
import com.app.youtubedownloader.R;
import com.squareup.picasso.Picasso;

import java.util.ArrayList;

public class MyAdapter extends BaseAdapter {

    public Activity activity;
    public ArrayList<VideoDetails> videoDetailsArrayList;
    public LayoutInflater inflater;

    public MyAdapter(Activity activity, ArrayList<VideoDetails> videoDetailsArrayList){
    this.activity = activity;
    this.videoDetailsArrayList = videoDetailsArrayList;
    }

    @Override
    public Object getItem(int position) {
        return this.videoDetailsArrayList.get(position);
    }

    @Override
    public long getItemId(int position) {
        return (long)position;
    }

    @Override
    public View getView(int position, View convertView, ViewGroup viewGroup) {

        if(inflater==null){
            inflater = this.activity.getLayoutInflater();
        }

        if( convertView==null){
            convertView = inflater.inflate(R.layout.list_item, null);
        }

        ImageView imageView =  convertView.findViewById(R.id.ImageView);
        TextView textView =  convertView.findViewById(R.id.titleofitem);

        LinearLayout linearLayout =  convertView.findViewById(R.id.root);
        final VideoDetails videoDetails = this.videoDetailsArrayList.get(position);
        linearLayout.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                Intent i = new Intent(activity, com.app.youtubedownloader.VideoPlay.class);
                i.putExtra("videoId",videoDetails.getVideoID());
                activity.startActivity(i);

            }
        });



        Picasso.get().load(videoDetails.getUrl()).into(imageView);
        textView.setText(videoDetails.getTitle());


        return  convertView;
    }

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

}

这是针对 getter 和 setter 的

public class VideoDetails {
    public String videoID, title, description, url;

    public  VideoDetails(String videoID,String title,String description,String url){
        this.videoID = videoID;
        this.title = title;
        this.description = description;
        this.url = url;
    }
    public VideoDetails(){

    }

    public String getVideoID() {
        return videoID;
    }

    public void setVideoID(String videoID) {
        this.videoID = videoID;
    }

    public String getTitle() {
        return title;
    }

    public void setTitle(String title) {
        this.title = title;
    }

    public String getDescription() {
        return description;
    }

    public void setDescription(String description) {
        this.description = description;
    }

    public String getUrl() {
        return url;
    }

    public void setUrl(String url) {
        this.url = url;
    }
}

我认为不需要 XML 文件。谢谢你!附:我尝试用 postman 测试我的网址请求，它有效。编辑:

 "kind": "youtube#searchListResponse",
 "etag": "\"p4VTdlkQv3HQeTEaXgvLePAydmU/zXtOj-qJByP8JvZOdTDcmmhSWNY\"",
 "nextPageToken": "CAMQAA",
 "regionCode": "MD",
 "pageInfo": {
  "totalResults": 1000000,
  "resultsPerPage": 3
 },
 "items": [
  {
   "kind": "youtube#searchResult",
   "etag": "\"p4VTdlkQv3HQeTEaXgvLePAydmU/XnyDQHIyLKnsfFTz76JxER0AjMg\"",
   "id": {
    "kind": "youtube#video",
    "videoId": "aBABkTN8n_w"
   },
   "snippet": {
    "publishedAt": "2018-12-17T12:07:35.000Z",
    "channelId": "UCod_t2sXD_gRI11yFFGkoXg",
    "title": "Best Funny Videos 2018 ● Cute girls doing funny things P3",
    "description": "Hi my friends, please check our new compilation. Here is moments people funny videos and we hope that this video make your life more fun & you enjoy it ...",
    "thumbnails": {
     "default": {
      "url": "https://i.ytimg.com/vi/aBABkTN8n_w/default.jpg",
      "width": 120,
      "height": 90
     },
     "medium": {
      "url": "https://i.ytimg.com/vi/aBABkTN8n_w/mqdefault.jpg",
      "width": 320,
      "height": 180
     },
     "high": {
      "url": "https://i.ytimg.com/vi/aBABkTN8n_w/hqdefault.jpg",
      "width": 480,
      "height": 360
     }
    },
    "channelTitle": "Vines best fun",
    "liveBroadcastContent": "none"
   }
  },
  {
   "kind": "youtube#searchResult",
   "etag": "\"p4VTdlkQv3HQeTEaXgvLePAydmU/W8J9Seta9NO6dAqIWb5gcwfliPo\"",
   "id": {
    "kind": "youtube#video",
    "videoId": "BgluGCjZKjM"
   },
   "snippet": {
    "publishedAt": "2017-06-20T17:26:22.000Z",
    "channelId": "UCeiZcfuj0r1ggNl0N_DVOgQ",
    "title": "Best FAILS & Funny Videos ★ June 2017 Compilation ★ FailCity",
    "description": "Best fails and funny videos compilation of the June 2017! Every week there's new funny fails and awesome win fail video compilations! ＳＵＢＳＣＲＩＢＥ ғᴏʀ ᴍᴏʀᴇ ...",
    "thumbnails": {
     "default": {
      "url": "https://i.ytimg.com/vi/BgluGCjZKjM/default.jpg",
      "width": 120,
      "height": 90
     },
     "medium": {
      "url": "https://i.ytimg.com/vi/BgluGCjZKjM/mqdefault.jpg",
      "width": 320,
      "height": 180
     },
     "high": {
      "url": "https://i.ytimg.com/vi/BgluGCjZKjM/hqdefault.jpg",
      "width": 480,
      "height": 360
     }
    },
    "channelTitle": "Net Fail",
    "liveBroadcastContent": "none"
   }
  },
  {
   "kind": "youtube#searchResult",
   "etag": "\"p4VTdlkQv3HQeTEaXgvLePAydmU/sy1iQ191YnpipX54MZQ-Z-bd2YU\"",
   "id": {
    "kind": "youtube#channel",
    "channelId": "UCUd0dDUCXsjBPnG1qeUHZLw"
   },
   "snippet": {
    "publishedAt": "2011-01-17T15:26:32.000Z",
    "channelId": "UCUd0dDUCXsjBPnG1qeUHZLw",
    "title": "funnyvideos",
    "description": "",
    "thumbnails": {
     "default": {
      "url": "https://yt3.ggpht.com/-mULWh9j1SAI/AAAAAAAAAAI/AAAAAAAAAAA/wtk972XjVNk/s88-c-k-no-mo-rj-c0xffffff/photo.jpg"
     },
     "medium": {
      "url": "https://yt3.ggpht.com/-mULWh9j1SAI/AAAAAAAAAAI/AAAAAAAAAAA/wtk972XjVNk/s240-c-k-no-mo-rj-c0xffffff/photo.jpg"
     },
     "high": {
      "url": "https://yt3.ggpht.com/-mULWh9j1SAI/AAAAAAAAAAI/AAAAAAAAAAA/wtk972XjVNk/s800-c-k-no-mo-rj-c0xffffff/photo.jpg"
     }
    },
    "channelTitle": "funnyvideos",
    "liveBroadcastContent": "upcoming"
   }
  }
 ]
}

Answer 1

哦，我想我已经明白了。看起来您的响应返回正常，在处理每个“项目”的“for”循环时，您将获取对象“id”，并且在该对象内部，您正在寻找“videoId”。这很好，除了三个结果中的最后一个之外，在 postman 结果中看起来像这样:

{
 "kind": "youtube#searchResult",
 "etag": "\"p4VTdlkQv3HQeTEaXgvLePAydmU/sy1iQ191YnpipX54MZQ-Z-bd2YU\"",
 "id": {
  "kind": "youtube#channel",
  "channelId": "UCUd0dDUCXsjBPnG1qeUHZLw"
 },

它有一个channelId而不是videoId。您应该做的是将每个 JSON 表达式捕获在它自己的 try/catch block 中，这样一个错误的响应就不会阻止您的整个结果。像这样的事情:

JSONObject jsonObject1 = jsonArray.getJSONObject(i);
JSONObject jsonId = jsonObject1.getJSONObject("id");
String video_id = "";
String channel_id = "";


try {

   video_id = jsonId.getString("videoId");

}catch(JSONException e) {
   channel_id = jsonId.getString("channelId");
}

您可以尝试添加更多日志记录，然后当您运行代码时，至少您会通过查看日志知道发生了什么:

    public void displayVideos(){
        RequestQueue requestQueue = Volley.newRequestQueue(getApplicationContext());

        url = "https://www.googleapis.com/youtube/v3/search?" + "part=" + part + "&q=" + keySearch + "&maxResults=3" + "&order=" + order + "&key=" + API_KEY;

        Log.i("My App", "url=" + url);

        StringRequest stringRequest = new StringRequest(Request.Method.GET, url, new Response.Listener<String>() {
            @Override
            public void onResponse(String response) {

                Log.i("My App", "response=" + response);

                try{
                    Log.i("My App", "before jsonObject");
                    JSONObject jsonObject = new JSONObject(response);
                    Log.i("My App", "after jsonObject:" + jsonObject.toString());

                    Log.i("My App", "before jsonArray");
                    JSONArray jsonArray = jsonObject.getJSONArray("items");
                    Log.i("My App", "after jsonArray: count=" + jsonArray.length());

                    for(int i=0; i<jsonArray.length(); i++){
                       Log.i("My App", "before jsonObject1");
                        JSONObject jsonObject1 = jsonArray.getJSONObject(i);
                       Log.i("My App", "after jsonObject1:" + jsonObject1.toString());

                        Log.i("My App", "before jsonVideoId");
                        JSONObject jsonVideoId = jsonObject1.getJSONObject("id");
                        Log.i("My App", "after jsonVideoId:" + jsonVideoId.toString());    

...  (your other code here)

                        Log.i("My App", "before videoId");  
                        String video_id = jsonVideoId.getString("videoId");
                        Log.i("My App", "after videoId:" + video_id); 

... (your other code here)   

                    }

                    listView.setAdapter(myadapter);
                    myadapter.notifyDataSetChanged();

                } catch(JSONException e){
                    Log.e("My App", e.getLocalizedMessage());
                    e.printStackTrace();
                }


            }
        }, new Response.ErrorListener() {
            @Override
            public void onErrorResponse(VolleyError error) {
               Log.e("My App", error.getMessage());
                Toast.makeText(getApplicationContext(),error.getMessage(),Toast.LENGTH_LONG).show();
            }
        });


        requestQueue.add(stringRequest);


    }

}