列表视图显示为空而不是数据显示

Question

我创建了一个应用程序，我从服务器获取数据并在列表视图中使用微调器显示数据，但我的列表视图显示为空我想显示数据，如bleow image

我的基础适配器是

public class Test_adapter extends BaseAdapter {

private Activity activity;
private LayoutInflater inflater;
private List<Audio_Model> movieItems;
private List<Audio_Model> adapterInitialMovieList = null;
ImageLoader imageLoader = AppController.getInstance().getImageLoader();

public Test_adapter(Activity activity, List<Audio_Model> movieItems) {
    this.activity = activity;
    this.movieItems = movieItems;
}
public void setDataOnSpinnerSelected(List<Audio_Model> audioList){
    adapterInitialMovieList  = audioList;
    notifyDataSetChanged();
}


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

@Override
public Object getItem(int location) {
    return movieItems.get(location);
}

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

@Override
public View getView(int position, View convertView, ViewGroup parent) {
    ViewHolder viewHolder;
    if (inflater == null) {
        inflater = (LayoutInflater) activity
                .getSystemService(Context.LAYOUT_INFLATER_SERVICE);
        if (convertView == null)
            convertView = inflater.inflate(R.layout.test_row, null);

        viewHolder = new ViewHolder();
        viewHolder.play = (ImageButton) convertView.findViewById(R.id.audioplay);
        viewHolder.stop = (ImageButton) convertView.findViewById(R.id.audiostop);
        viewHolder.seekBar = (SeekBar) convertView.findViewById(R.id.seekbar_audio1);
        viewHolder.share = (ImageButton) convertView.findViewById(R.id.audioshare1);
    }else{
        viewHolder =(ViewHolder)convertView.getTag();
    }
    viewHolder.play.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {

        }
    });
    viewHolder.stop.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {

        }
    });

    viewHolder.share.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {

        }
    });

    viewHolder.seekBar.setOnSeekBarChangeListener(new SeekBar.OnSeekBarChangeListener() {
        @Override
        public void onProgressChanged(SeekBar seekBar, int progress, boolean fromUser) {

        }

        @Override
        public void onStartTrackingTouch(SeekBar seekBar) {

        }

        @Override
        public void onStopTrackingTouch(SeekBar seekBar) {

        }
    });

    return convertView;
}

public class ViewHolder {
    SeekBar seekBar;
    ImageButton play,stop,share;
}

}

和活动

private Spinner mSpinner;
ArrayList<String> students;
private JSONArray result;


private static final String TAG = MainActivity.class.getSimpleName();
private static final String url = "http://www.example.com/json_audio.php";
private ProgressDialog pDialog;
private List<Audio_Model> audioList = new ArrayList<Audio_Model>();
private ListView audio_List;
private Audio_Adapter adapter;
Json_Data j_Data = new Json_Data();

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.audio_activity);
    students = new ArrayList<String>();
    audio_List = (ListView) findViewById(R.id.audio_list);
    mSpinner =(Spinner)findViewById(R.id.audioSpinner);
    listdata();
    getData();
    adapter = new Audio_Adapter(this, audioList);
    audio_List.setAdapter(adapter);
    mSpinner.setOnItemSelectedListener(this);
    students.add("Get Category");
    audio_List.setOnItemClickListener(new AdapterView.OnItemClickListener() {
        @Override
        public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
            String link=  audioList.get(position).getAudiolink();
            Intent audointent = new Intent(getApplicationContext(),Audio_PlayActivity.class);
            audointent.putExtra("link",link);
            startActivity(audointent);
            finish();
            Log.e("hello audio","link==>"+link);
        }
    });
    pDialog = new ProgressDialog(this);
    pDialog.setMessage("Loading...");
    pDialog.show();
}
public void listdata(){
    // Creating volley request obj
    JsonArrayRequest movieReq = new JsonArrayRequest(url,
            new Response.Listener<JSONArray>() {
                @Override
                public void onResponse(JSONArray response) {
                    Log.d(TAG, response.toString());
                    hidePDialog();

                    // Parsing json
                    for (int i = 0; i < response.length(); i++) {
                        try {

                            JSONObject obj = response.getJSONObject(i);
                            Audio_Model _audio = new Audio_Model();
                            Test_model test_model= new Test_model();
                            _audio.setAudioname(obj.getString("txt"));
                            _audio.setThumbnailUrl(obj.getString("audio_img"));
                            _audio.setAudiolink(obj.getString("audio"));
                            audioList.add(_audio);

                        } catch (JSONException e) {
                            e.printStackTrace();
                        }
                    }
                    // notifying list adapter about data changes
                    // so that it renders the list view with updated data
                    adapter.notifyDataSetChanged();
                }
            }, new Response.ErrorListener() {
        @Override
        public void onErrorResponse(VolleyError error) {
            VolleyLog.d(TAG, "Error: " + error.getMessage());
            hidePDialog();

        }
    });

    // Adding request to request queue
    AppController.getInstance().addToRequestQueue(movieReq);
}

private void getData() {


    StringRequest stringRequest = new StringRequest(Config.DATA_URL,
            new Response.Listener<String>() {
                @Override
                public void onResponse(String response) {
                    JSONObject j_obj = null;
                    try {
                        j_obj = new JSONObject(response);
                        result = j_obj.getJSONArray(Config.JSON_ARRAY);
                        //Calling method getStudents to get the students from the JSON Array
                        getStudents(result);
                    } catch (JSONException e) {
                        e.printStackTrace();
                    }
                }
            },
            new Response.ErrorListener() {
                @Override
                public void onErrorResponse(VolleyError error) {
                }
            });
    RequestQueue requestQueue = Volley.newRequestQueue(this);
    requestQueue.add(stringRequest);
}
private void getStudents(JSONArray j) {
    for (int i = 0; i < j.length(); i++) {
        try {
            JSONObject json = j.getJSONObject(i);
            students.add(json.getString(Config.TAG_USERNAME));
        } catch (JSONException e) {
            e.printStackTrace();
        }
    }
    //Setting adapter to show the items in the spinner
    mSpinner.setAdapter(new ArrayAdapter<String>(Audio_Activity.this, android.R.layout.simple_spinner_dropdown_item, students));
}

public void onItemSelected(AdapterView<?> parent, View view, int position, long id)
{
    String text_spinner1 = mSpinner.getSelectedItem().toString();
    j_Data.setSpintext(text_spinner1);
    makeJsonArrayRequest();
}
@Override
public void onNothingSelected(AdapterView<?> parent)
{
}


@Override
public void onDestroy() {
    super.onDestroy();
    hidePDialog();
}

private void hidePDialog() {
    if (pDialog != null) {
        pDialog.dismiss();
        pDialog = null;
    }
}

但列表视图显示为空白

帮助我在哪里做错了