refreshScreen

private void refreshScreen() {
        Call<List<Course>> call = restClient.getService().getCourse();
        call.enqueue(new Callback<List<Course>>() {
                         @Override
                         public void onResponse(Call<List<Course>> call, Response<List<Course>> response) {
                             ListView lv = (ListView) findViewById(R.id.listView);


                             ArrayList<HashMap<String, String>> courseList = new ArrayList<HashMap<String, String>>();

                             for (int i = 0; i < response.body().size(); i++) {
                                 HashMap<String, String> course = new HashMap<String, String>();

                                 if (response.body().get(i).getUserId().equals(Global_config._USER_ID_CUR)) {
                                     course.put("id", String.valueOf(response.body().get(i).getId()));
                                     course.put("name", String.valueOf(response.body().get(i).getName()));

                                     courseList.add(course);
                                 }
                             }

                             lv.setOnItemClickListener(new AdapterView.OnItemClickListener() {
                                 @Override
                                 public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
                                     course_Id = (TextView) view.findViewById(R.id.user_Id);
                                     courseId = course_Id.getText().toString();

                                     course_name = (TextView) view.findViewById(R.id.user_name);
                                     courseName = course_name.getText().toString();

                                     Intent objIndent = new Intent(getApplicationContext(), CourseManagerActivity.class);
                                     objIndent.putExtra("course_Id", courseId);
                                     objIndent.putExtra("course_title", courseName);
                                     startActivity(objIndent);
                                 }
                             });
                             ListAdapter adapter = new SimpleAdapter(TeacherActivity.this, courseList, R.layout.view_user_entry, new String[]{"id", "name"}, new int[]{R.id.user_Id, R.id.user_name});
                             lv.setAdapter(adapter);
                         }

                         @Override
                         public void onFailure(Call<List<Course>> call, Throwable t) {
                             Toast.makeText(TeacherActivity.this, t.getMessage(), Toast.LENGTH_LONG).show();

                         }
                     }
        );


    }