无法刷新 Spinner 所选项目的 ListView 以从 url 获取新数据

Posted 2023-04-19

【中文标题】无法刷新 Spinner 所选项目的 ListView 以从 url 获取新数据

【英文标题】：not able to refresh the ListView on Spinner's selected item to get new data from url

【发布时间】：2018-08-30 13:20:32

【问题描述】：

我无法刷新微调器项目选择的列表视图。 我想根据 spinner 的 items 值构建新的 url 以获取新的 json 数据并转换为 listview。 您还可以帮助我告诉我如何创建一种方法来传递新的 url 以获取新数据。

主要问题与标题相同 您的每一个帮助将不胜感激。

@覆盖 public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) // 膨胀这个片段的布局 View view = inflater.inflate(R.layout.fragment1, container, false);

String [] array_values = "All "," 5"," 4"," 3"," 2"," 1";
final Spinner spinner = view.findViewById(R.id.spinner);

final ArrayAdapter<String> spinner_adapter = new ArrayAdapter<>(this.getActivity(), android.R.layout.simple_spinner_item, array_values);
spinner_adapter.setDropDownViewResource(android.R.layout.simple_dropdown_item_1line);
spinner.setAdapter(spinner_adapter);

final String spinnerValue = spinner.getSelectedItem().toString();
url = "http://website.com/demo.php?pswd=kvpswd";

listView = (ListView) view.findViewById(R.id.demo_list_view);
adapter = new CustomListAdapter(this.getActivity(), List);
listView.setAdapter(adapter);

spinner.setOnItemSelectedListener(new AdapterView.OnItemSelectedListener() 
    public void onItemSelected(AdapterView<?> parent, View view, int pos, long id) 
      //  listView.setAdapter(null);
      String spinnerValue = spinner.getSelectedItem().toString();
        url = "http://website.com/demo.php?pswd="+spinnerValue;
        adapter.notifyDataSetChanged();
    
    public void onNothingSelected(AdapterView<?> parent) 

    
);

// Creating volley request obj
JsonArrayRequest Requset = 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);

                        DataFetcher datafetcher = new DataFetcher();

                        datafetcher.set1(obj.getString("item1"));
                        datafetcher.set2(obj.getString("item2"));
                        datafetcher.set3(obj.getString("item3"));
                        datafetcher.set4(obj.getString("item4"));
                        datafetcher.set5(obj.getString("item5"));
                        datafetcher.set6(obj.getString("item6"));
                        datafetcher.set7(obj.getString("item7"));
                        datafetcher.set8(obj.getString("item8"));

                        // adding list to list array
                        List.add(datafetcher);

                     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();

    
);

【参考方案1】：

为 api 调用和传递 url 和设置数据到列表视图的方法。 下面的方法进入微调器选择时间。

 private void callApiData(String url)
    // Creating volley request obj
    JsonArrayRequest Requset = 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);

                            DataFetcher datafetcher = new DataFetcher();

                            datafetcher.set1(obj.getString("item1"));
                            datafetcher.set2(obj.getString("item2"));
                            datafetcher.set3(obj.getString("item3"));
                            datafetcher.set4(obj.getString("item4"));
                            datafetcher.set5(obj.getString("item5"));
                            datafetcher.set6(obj.getString("item6"));
                            datafetcher.set7(obj.getString("item7"));
                            datafetcher.set8(obj.getString("item8"));

                            // adding list to list array
                            List.add(datafetcher);
                            setAdapter();
                         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();

        
    );

并且还为适配器设置另一种方法。

  private void setAdapter()
    if(adpter==null)
        adapter = new CustomListAdapter(this.getActivity(), List);
        listView.setAdapter(adapter);
        adapter.notifyDataSetChanged();
    
    else
        adapter.notifyDataSetChanged();
    

【讨论】：

它无法正常工作..它将新数据从 url 添加到列表视图的末尾而不清除旧数据..请帮助我

当你获取数据时，时间列表将像获取数据之前使用的 List.clear() 方法一样被清除。 // 在你的数组列表对象中列出。