Question

我正在尝试使用API在自定义listView中显示数据没有错误，但自定义列表中没有显示数据.i是单独的 asyncTask，Adapters和model的类。 asyncTask的代码是

public class CourseOutlinesTask extends AsyncTask<String, String, String> {
    ProgressDialog dialog;
    Context context;
    private ArrayList<CourseModel> postList = new ArrayList<CourseModel>();
    private ListView listView;
    private View root;
    TrainerCourseAdapter adapter;
    String json_string;
    @Override
    protected void onPreExecute() {

    }

    @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);
            }
            return buffer.toString();
        } catch (MalformedURLException e) {
            e.printStackTrace();
        } catch (IOException 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);
        //close process dialog
        if (this.dialog != null) {
            this.dialog.dismiss();
        }
        //parse json
        try {
            JSONObject jsonParse = new JSONObject(result);
            JSONArray query = jsonParse.getJSONArray("courses");
            for (int i = 0; i < query.length(); i++) {
                try {
                    JSONObject jsonParser = query.getJSONObject(i);
                    CourseModel post = new CourseModel();
                    post.setId(jsonParser.getInt("id"));
                    post.setTitle(jsonParser.getString("title"));
                    post.setStatus(jsonParser.getString("status"));
                    post.setDescription(jsonParser.getString("description"));
                    System.out.println(post.getStatus()+"asdadasdad");
                    System.out.println(post);
                    postList.add(post);
                    TrainerCourseAdapter adapter = new TrainerCourseAdapter(context,postList);
        }catch (Exception e) {
                    System.out.println(e);
        }
            // Parsing json
                    post.setDescription(obj.getString("description"));

                    // ****Handle CreationDate-Object
                      // Genre is json array
            }
        } else {
            MyAppUtil.getToast(getApplicationContext(), message);
        }*/
    }
    } catch (JSONException e) {
            e.printStackTrace();
        }
    }
}

我的适配器类的代码是

public class TrainerCourseAdapter extends BaseAdapter {
private  List list;
    private Context context;
    private static LayoutInflater inflater = null;

    String [] cName;
    String [] cDetail;
    String [] created;
    String [] cStatus;
    TextView c_name,c_detail,c_date,c_status;
    ArrayList<CourseModel> itemList;
    Context mcontext;
    public TrainerCourseAdapter(Context context,List list) {
        mcontext = context;
        itemList = (ArrayList<CourseModel>) list;
    }
    @Override
    public int getCount() {
        return itemList.size();
    }

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

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


    public void setItemList(ArrayList<CourseModel> itemList) {
        this.itemList = itemList;
    }

    public class Holder
    {
        TextView c_name;
        TextView c_detail;
        TextView c_date ;
        Button c_status;
    }

    @Override
    public View getView(final int i, View view, ViewGroup viewGroup) {
        Holder holder = new Holder();
        View rowView;
        rowView = inflater.inflate(R.layout.row_courses_list, viewGroup,false);
         this.c_name = (TextView) rowView.findViewById(R.id.txt_courseName);
        this.c_detail = (TextView) rowView.findViewById(R.id.txt_courseDetail);
        this.c_date = (TextView) rowView.findViewById(R.id.txt_courseDate);
        this.c_status = (Button) rowView.findViewById(R.id.btn_courseStatus);
 System.out.println("Mudassir Don");

        final CourseModel data = itemList.get(i);
        this.c_name.setText(data.getTitle());
        this.c_detail.setText(data.getDescription());
        this.c_status.setText(data.getStatus());
        this.c_date.setText(data.getId());
        System.out.println(c_date);
        rowView.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                Toast.makeText(context, "You Clicked "+ cName[i], Toast.LENGTH_LONG).show();
            }
        });
        return rowView;
    }
}

活动代码是

     super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_course_outlines);
        CourseOutlinesTask task = new CourseOutlinesTask();
        task.execute("http://mantis.vu.edu.pk/bridging_the_gap/public/viewCourseOutlines");
        mylist = task.viewResult();
  listView = (ListView) findViewById(R.id.course_listView);
        listView.setAdapter(new TrainerCourseAdapter(CourseOutlinesActivity.this,mylist ) {
        });

Answer 1

您需要将自定义适配器分配给listView。

onPostExecute

在您的情况下，CourseOutlinesTask TrainerCourseAdapter adapter = new TrainerCourseAdapter(context,postList); listView = (ListView) findViewById(R.id.course_listView); listview.setAdapter(adapter);方法内部应该写出来。

getUser(){
    return Observable.create(s => {
      if(!this.user)
        this.connection.identity((err, res) => {
          this.user = res;
          s.next(res);
          s.complete();
        })
      else{
        s.next(this.user);
        s.complete();
      }
    });
  }

希望这有帮助。

Answer 2

您需要在活动中编写接口并获取响应，并将适配器设置为列表视图等。

TrainerCourseAdapter adapter = new TrainerCourseAdapter(context,postList);
listView = (ListView) findViewById(R.id.course_listView);
listview.setAdapter(adapter);

Answer 3

您可以使用callBack接口将itemArraylist数据添加到您的活动类。在活动类中获取项目列表数据后，您可以将适配器设置为listview。

TrainerCourseAdapter adapter = new TrainerCourseAdapter(context, postList);
listView = (ListView) findViewById(R.id.course_listView);
listview.setAdapter(adapter);

//您可以在CourseOutlinesClass中使用两个方法onSuccess（）和onFailure（）创建接口，并在onPostExecute（）中使用此接口将arraylist数据发送到activity，然后设置适配器以填充listview中的数据。

Answer 4

使用以下代码： -

protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_course_outlines);
        listView = (ListView) findViewById(R.id.course_listView);
        new CourseOutlinesTask().execute("http://mantis.vu.edu.pk/bridging_the_gap/public/viewCourseOutlines");
}

并在你的AsyncTask setAdapter的postExecute中列表视图

TrainerCourseAdapter adapter = new TrainerCourseAdapter(context,postList);
listView.setAdapter(adapter);

我正在尝试使用api显示数据。但数据未显示在自定义listView中。列表是空的

4 个答案: