Question

我是android编程的新手，我成功从服务器获取数据然后填充到listview中。但是如何在一定时间内自动刷新listview项目？当我刷新新项目时，可能会出现从服务器进入的新项目。

这是我从服务器检索数据的代码：

public class TabActivityQueue extends Fragment {

ListView list;
TextView number;
TextView info;
TextView remark;
TextView statuss;
Button Btngetdata;
ArrayList<HashMap<String, String>> oslist = new ArrayList<HashMap<String, String>>();

//URL to get JSON Array
private static String url = "http://172.22.85.235:8080/Qproject/servlet/Qaction?action_flag=find";

//JSON Node Names 
private static final String Table2 = "table2";
private static final String phonenumber = "phonenumber";
private static final String peoplenumber = "peoplenumber";
private static final String remarks = "remarks";
private static final String status = "status";

JSONArray table2 = null;



 public View onCreateView(LayoutInflater inflater, ViewGroup container, 
            Bundle savedInstanceState) {
            // Inflate the layout for this fragment
            //This layout contains your list view 
                View view = inflater.inflate(R.layout.activity_tab_activity_queue, container, false);


             return view;
            }


@Override
public void onActivityCreated(Bundle savedInstanceState) {
// TODO Auto-generated method stub
super.onActivityCreated(savedInstanceState);

oslist = new ArrayList<HashMap<String, String>>();
Btngetdata = (Button)getView().findViewById(R.id.getdata);
Btngetdata.setOnClickListener(new View.OnClickListener() {
    @Override
    public void onClick(View view) {
        new JSONParse().execute();  
    }
});

}

private class JSONParse extends AsyncTask<String, String, JSONObject> {
     public ProgressDialog pDialog;
    @Override
   protected void onPreExecute() {
   super.onPreExecute();
   number = (TextView)getView().findViewById(R.id.number);
     info = (TextView)getView().findViewById(R.id.info);
     remark = (TextView)getView().findViewById(R.id.remark);
     statuss = (TextView)getView().findViewById(R.id.statuss);
   pDialog = new ProgressDialog(getActivity());
   pDialog.setMessage("Getting Data ...");
   pDialog.setIndeterminate(false);
   pDialog.setCancelable(true);
   pDialog.show();



}

@Override
   public JSONObject doInBackground(String... args) {

    JSONParser jParser = new JSONParser();

    // Getting JSON from URL
    JSONObject json = jParser.getJSONFromUrl(url);
    return json;
}
 @Override
public void onPostExecute(JSONObject json) {
     pDialog.dismiss();
     try {
            // Getting JSON Array from URL
            table2 = json.getJSONArray(Table2);
            for(int i = 0; i < table2.length(); i++){
            JSONObject c = table2.getJSONObject(i);

            // Storing  JSON item in a Variable
            String number = c.getString(phonenumber);
            String info = c.getString(peoplenumber);
            String remark = c.getString(remarks);
            String statuss = c.getString(status);




            // Adding value HashMap key => value


            HashMap<String, String> map = new HashMap<String, String>();

            map.put(phonenumber, number);
            map.put(peoplenumber, info);
            map.put(remarks, remark);
            map.put(status, statuss);

            oslist.add(map);
            list=(ListView)getView().findViewById(R.id.list);





            ListAdapter adapter = new SimpleAdapter(getActivity(), oslist,
                    R.layout.list_view,
                    new String[] { phonenumber,peoplenumber, remarks,status }, new int[] {
                            R.id.number,R.id.info, R.id.remark,R.id.statuss});

            list.setAdapter(adapter);
            list.setOnItemClickListener(new AdapterView.OnItemClickListener() {

                @Override
                public void onItemClick(AdapterView<?> parent, View view,
                                        int position, long id) {
                    //Toast.makeText(getActivity(), "You Clicked at "+oslist.get(+position).get("name"), Toast.LENGTH_SHORT).show();
                    String numberr = oslist.get(position).get("phonenumber");
                     Intent intent = new Intent(getActivity(), ThreeButton.class);
                     intent.putExtra("key", numberr);
                     startActivity(intent);
                 } 
                }
            );

            }
    } catch (JSONException e) {
        e.printStackTrace();
    }


 }
}
}

Answer 1

我建议您使用处理程序刷新数据。即

final Handler handler = new Handler();

Runnable refresh = new Runnable() {
        @Override
        public void run() {
            new JSONParse().execute();  
            handler.postDelayed(this, 60 * 1000);
        }
    };

handler.postDelayed(refresh, 60 * 1000);

此处理程序每分钟刷新一次数据。

Answer 2

要防止在列表视图中添加相同的数据，您应该使用以下内容：

请在for循环之前的AsyncTask的onPost（）方法中粘贴以下代码：

if(oslist!=null && oslist.size()>0)
      oslist.clear();

android自动刷新listview项目

2 个答案: