Question

我正在使用api开发一个app来显示列表，listview包含数据。但是当我运行项目时，活动显示空白结果并显示logcat＆＃34;程序＆＃34;（即阵列名称）＆＃39;信息。如何显示以下代码的结果？

public class MainActivity extends Activity {
        // Declare Variables
        JSONObject jsonobject;
        JSONArray jsonarray;
        ListView listview;
        ListViewAdapter adapter;
        ProgressDialog mProgressDialog;
        ArrayList<HashMap<String, String>> arraylist;

        static String AID = "asanaid";
        static String ANAME = "asananame";
        static String DURATION = "duration";
        static String IMGURL = "imgeurl";
        static String IMGVERSION = "imgeversion";
        static String AUDIOURL = "audiourl";
        static String AUDIOVERSION = "audioversion";


        @Override
        public void onCreate(Bundle savedInstanceState) {
            super.onCreate(savedInstanceState);
            // Get the view from listview_main.xml
            setContentView(R.layout.activity_relaxation_lv);
            // Execute DownloadJSON AsyncTask
            new DownloadJSON().execute();
        }

        // DownloadJSON AsyncTask
        private class DownloadJSON extends AsyncTask<Void, Void, Void> {

            @Override
            protected void onPreExecute() {
                super.onPreExecute();
                // Create a progressdialog
                mProgressDialog = new ProgressDialog(MainActivity.this);
                // Set progressdialog title
                mProgressDialog.setTitle("Android JSON Parse Tutorial");
                // Set progressdialog message
                mProgressDialog.setMessage("Loading...");
                mProgressDialog.setIndeterminate(false);
                // Show progressdialog
                mProgressDialog.show();
            }

            @Override
            protected Void doInBackground(Void... params) {
                // Create an array
                arraylist = new ArrayList<HashMap<String, String>>();
                // Retrieve JSON Objects from the given URL address
                jsonobject = JSONfunctions
                        .getJSONfromURL("http://www.....");

                try {
                    // Locate the array name in JSON
                    jsonarray = jsonobject.getJSONArray("program");

                    for (int i = 0; i < jsonarray.length(); i++) {
                        HashMap<String, String> map = new HashMap<String, String>();
                        jsonobject = jsonarray.getJSONObject(i);
                        // Retrive JSON Objects
                        map.put("asanaid", jsonobject.getString("asanaid"));
                        map.put("asananame", jsonobject.getString("asananame"));
                        map.put("duration", jsonobject.getString("duration"));
                        map.put("imgeurl", jsonobject.getString("imgeurl"));
                        map.put("imgeversion", jsonobject.getString("imgeversion"));
                        map.put("audiourl", jsonobject.getString("audiourl"));
                        map.put("audioversion", jsonobject.getString("audioversion"));

                        // Set the JSON Objects into the array
                        arraylist.add(map);
                    }
                } catch (JSONException e) {
                    Log.e("Error", e.getMessage());
                    e.printStackTrace();
                }
                return null;
            }

            @Override
            protected void onPostExecute(Void args) {
                // Locate the listview in listview_main.xml
                listview = (ListView) findViewById(R.id.listview);
                // Pass the results into ListViewAdapter.java
                adapter = new ListViewAdapter(MainActivity.this, arraylist);
                // Set the adapter to the ListView
                listview.setAdapter(adapter);
                // Close the progressdialog
                mProgressDialog.dismiss();
            }
        }
    }


    public class ListViewAdapter extends BaseAdapter{

    // Declare Variables
    Context context;
    LayoutInflater inflater;
    ArrayList<HashMap<String, String>> data;
    ImageLoader imageLoader;
    HashMap<String, String> resultp = new HashMap<String, String>();

public ListViewAdapter(Context context,
        ArrayList<HashMap<String, String>> arraylist) {
    this.context = context;
    data = arraylist;
    imageLoader = new ImageLoader(context);
}

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

    @Override
    public Object getItem(int position) {
    return null;
}

    @Override
    public long getItemId(int position) {
    return 0;
}

public View getView(final int position, View convertView, ViewGroup parent) {
    // Declare Variables
    TextView tvAname, tvId, imgUrl, imgVersion, audioUrl, audioVersion, duration;
    ImageView imgPose;

    inflater = (LayoutInflater) context
            .getSystemService(Context.LAYOUT_INFLATER_SERVICE);

    View itemView = inflater.inflate(R.layout.relaxationlv_single_item, parent, false);
    // Get the position
    resultp = data.get(position);

    // Locate the TextViews in listview_item.xml
    tvAname = (TextView) itemView.findViewById(R.id.lv_aname);
    tvAname.setText(resultp.get(MainActivity.ANAME));

    tvId = (TextView)itemView.findViewById(R.id.lv_aid);
    tvId.setText(resultp.get(MainActivity.AID));

    duration = (TextView)itemView.findViewById(R.id.lv_duration);
    duration.setText(resultp.get(MainActivity.DURATION));

    imgVersion = (TextView)itemView.findViewById(R.id.lv_imgversion);
    imgVersion.setText(resultp.get(MainActivity.IMGURL));

    audioVersion = (TextView)itemView.findViewById(R.id.lv_audioversion);
    audioVersion.setText(resultp.get(MainActivity.AUDIOVERSION));

    audioUrl= (TextView)itemView.findViewById(R.id.lv_audiourl);
    audioUrl.setText(resultp.get(MainActivity.AUDIOURL));

    imgPose = (ImageView)itemView.findViewById(R.id.lv_imgurl);
    imageLoader.DisplayImage(resultp.get(MainActivity.IMGURL), imgPose);

    // Capture ListView item click
    itemView.setOnClickListener(new View.OnClickListener() {

        @Override
        public void onClick(View arg0) {
            // Get the position
            resultp = data.get(position);
            Intent intent = new Intent(context, RelaxationLvAudioPlayerActivity1.class);
            intent.putExtra("asanaid", resultp.get(MainActivity.AID));
            intent.putExtra("asananame", resultp.get(MainActivity.ANAME));
            intent.putExtra("duration", resultp.get(MainActivity.DURATION));
            intent.putExtra("imgeurl", resultp.get(MainActivity.IMGURL));
            intent.putExtra("imgeversion", resultp.get(MainActivity.IMGVERSION));
            intent.putExtra("audiourl", resultp.get(MainActivity.AUDIOURL));
            intent.putExtra("audioversion", resultp.get(MainActivity.AUDIOVERSION));
            context.startActivity(intent);

        }
    });
    return itemView;
  }
}

Answer 1

您收到了JSONException -

请检查JSON响应中是否缺少以下字段之一 -

map.put("asanaid", jsonobject.getString("asanaid"));
                        map.put("asananame", jsonobject.getString("asananame"));
                        map.put("duration", jsonobject.getString("duration"));
                        map.put("imgeurl", jsonobject.getString("imgeurl"));
                        map.put("imgeversion", jsonobject.getString("imgeversion"));
                        map.put("audiourl", jsonobject.getString("audiourl"));
                        map.put("audioversion", jsonobject.getString("audioversion"));

您可以检查此购买打印jsonobject.getString（“asaname”）的值等等。

或者另一种情况可能是值不同的dataType。例如。您试图以字符串形式获取的音频回放，但在JSON中它是Integer的类型。

活动显示空白结果？

1 个答案: