android - JsonAdapter 无法打印数据

Question

我关注这个video尝试从 mongodb 获取数据 从 mongodb 获取 JsonArray，并使用 Debug模式检查 JsonTest.java 类:ArrayList<JsonSongs> songlist;里面有 21 条数据，而且都是正确的，listview 显示了 21 行，但不知何故数据没有显示在 textview 上，

我认为 JsonTest.java 类: ˋArrayList 歌曲列表； did pass the data to class JsonSongAdapter.java ˋArrayList<JsonSongs> songlist;正确的？请帮忙，卡在这里好几个小时了

JsonTest.java

public class JsonTest extends Activity {

ListView list;
ArrayList<JsonSongs> songlist;
   private TextView test;


@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.jsonmain);
    list = (ListView)findViewById(R.id.JsonlistView);
    songlist = new ArrayList<JsonSongs>();
    new JsonTalk().execute("http://192.168.1.102:3000/songs");

       }





class JsonTalk extends AsyncTask< String , String ,String>{

    @Override
    protected String doInBackground(String... params) {
        HttpURLConnection connection = null;
        BufferedReader reader = null;

        try {
            URL url = new URL(params[0]);
            connection = (HttpURLConnection) url.openConnection();
            connection.connect();

            InputStream stream = connection.getInputStream();
            reader = new BufferedReader(new InputStreamReader(stream));
            StringBuffer buffer = new StringBuffer();
            String line = "";
            while ((line = reader.readLine()) != null) {
                buffer.append(line);
            }
            String finalJson = buffer.toString();
           // JSONObject parentJsonObject = new JSONObject(finalJson);
            JSONArray jsonArray = new JSONArray(finalJson);
            JsonSongs jsonSongs = new JsonSongs();
            for (int i = 0 ; i < jsonArray.length();i++){
                JSONObject finaObject = jsonArray.getJSONObject(i);
                jsonSongs.set_id(finaObject.getString("_id"));
                jsonSongs.setDecade(finaObject.getString("decade"));
                jsonSongs.setArtist(finaObject.getString("artist"));
                jsonSongs.setSong(finaObject.getString("song"));
                jsonSongs.setWeeksAtOne(finaObject.getInt("weeksAtOne"));
                songlist.add(jsonSongs);
            }

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

        finally {
            if (connection != null) {
                connection.disconnect();
            }
            try {
                if (reader != null) {
                    reader.close();
                }
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
        return null;
    }

    @Override
    protected void onPostExecute(String result) {
        super.onPostExecute(result);
        if(result == null){
            JsonSonAdapter adapter = new JsonSonAdapter(getApplicationContext(),R.layout.jsonlayout,songlist);
            list.setAdapter(adapter);
        }else {
            Toast.makeText(JsonTest.this,"NOP",Toast.LENGTH_LONG).show();
        }
    }
}
}

JsonSonAdapter

public class JsonSonAdapter extends ArrayAdapter<JsonSongs> {
ArrayList<JsonSongs> songList;
int Resource;
Context context;
LayoutInflater vi;

public JsonSonAdapter(Context context, int resource, ArrayList<JsonSongs> objects) {
    super(context, resource, objects);
    songList = objects;
    Resource = resource;
    this.context = context;
    vi = (LayoutInflater) context.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
}

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

    ViewHolder holder;
    if(convertView == null){
       convertView = vi.inflate(Resource,null);
        holder = new ViewHolder();
        holder.textJson_ID=(TextView)convertView.findViewById(R.id.textJson_ID);
        holder.textJSONname=(TextView)convertView.findViewById(R.id.textJSONname);
        holder.textJsonSong=(TextView)convertView.findViewById(R.id.textJsonSong);
        holder.textJsonYear=(TextView)convertView.findViewById(R.id.textJsonYear);
        holder.textJsonWeeks=(TextView)convertView.findViewById(R.id.textJsonWeeks);
        convertView.setTag(holder);
    }else {
        holder = (ViewHolder)convertView.getTag();
    }

    return convertView;
}

static class ViewHolder{

 public TextView textJsonYear;
 public TextView textJSONname;
 public TextView textJsonSong;
 public TextView textJsonWeeks;
 public TextView textJson_ID;
 }

}

JsonSongs

public class JsonSongs {

private String _id;
private String decade;
private String artist;
private String song;
private int weeksAtOne;

public String get_id() {
    return _id;
}

public void set_id(String _id) {
    this._id = _id;
}

public String getArtist() {
    return artist;
}

public void setArtist(String artist) {
    this.artist = artist;
}

public String getDecade() {
    return decade;
}

public void setDecade(String decade) {
    this.decade = decade;
}

public String getSong() {
    return song;
}

public void setSong(String song) {
    this.song = song;
}

public int getWeeksAtOne() {
    return weeksAtOne;
}

public void setWeeksAtOne(int weeksAtOne) {
    this.weeksAtOne = weeksAtOne;
}




}

Answer 1

but somehow the data did't show on the textview ,

您没有设置它，所以不足为奇。完成 convertView 后，您需要在 EditText 上调用 setText()(在 getView() 中)以用数据填充它。

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

    ViewHolder holder;
    if(convertView == null){
       convertView = vi.inflate(Resource,null);
        holder = new ViewHolder();
        holder.textJson_ID=(TextView)convertView.findViewById(R.id.textJson_ID);
        ...
        convertView.setTag(holder);
    }else {
        holder = (ViewHolder)convertView.getTag();
    }


    // populate it with data
    JsonSongs song = songs.get(position);
    holder.textJson_ID.setText(song.getSomething());
    ...


    return convertView;
}

PS:JsonSongs 应该命名为JsonSong。你的命名模式一团糟。