问题描述

在列表中添加值后，却检索不出来

在一个列表中我使用add(intObject)方法添加了一个值，但是当我使用get(int)方法检索值的时候，却还是获得上次添加的值，并不是这次新添加的值。
谁能给出适当的建议呢？
我使用的下面的代码：

public static List getCompanyName(String user_id) {    List<CustomerList> fetchDatefromID = new ArrayList<CustomerList>();    CustomerList tempProgram = new CustomerList();    String result = """";    InputStream is = null;    ArrayList<NameValuePair> nameValuePairs = new ArrayList<NameValuePair>();    nameValuePairs.add(new BasicNameValuePair(""q""" + user_id));    // http post    try {        HttpClient httpclient = new DefaultHttpClient();        HttpPost httppost = new HttpPost(https://erestaurantonline.co.uk/kernow_mobile/customer_search.php?"");        httppost.setEntity(new UrlEncodedFormEntity(nameValuePairs));        HttpResponse response = httpclient.execute(httppost);        HttpEntity entity = response.getEntity();        is = entity.getContent();    } catch (Exception e) {        Log.e(""log_tag""Error in http connection "" + e.toString());    }    // convert response to string    try {        BufferedReader reader = new BufferedReader(new InputStreamReader(                isiso-8859-1"") 8);        StringBuilder sb = new StringBuilder();        String line = null;        while ((line = reader.readLine()) != null) {            sb.append(line + ""n"");        }        is.close();        result = sb.toString();    } catch (Exception e) {        Log.e(""log_tag""Error converting result "" + e.toString());    }    // parse json data    try {        JSONArray jArray = new JSONArray(result);        for (int i = 0; i < jArray.length(); i++) {            JSONObject json_data = jArray.getJSONObject(i);            if (json_data.getString(""company"") != null) {                tempProgram.setCompanyName(json_data.getString(""company""));                tempProgram.setID(json_data.getString(""id""));                fetchDatefromID.add(i tempProgram);            }        }    } catch (JSONException e) {        Log.e(""log_tag""Error parsing data "" + e.toString());    }    for (int i = 0; i < fetchDatefromID.size(); i++) {        Log.v(""log_tag""DataMy  :  ""+fetchDatefromID.get(i).getCompanyName().toString());    }    return fetchDatefromID;}

解决方案

把下面的代码：

if (json_data.getString(""company"") != null) {                tempProgram.setCompanyName(json_data.getString(""company""));                tempProgram.setID(json_data.getString(""id""));                fetchDatefromID.add(i tempProgram);            }

换成：

if (json_data.getString(""company"") != null) {                tempProgram = new CustomerList();                tempProgram.setCompanyName(json_data.getString(""company""));                tempProgram.setID(json_data.getString(""id""));                fetchDatefromID.add(i tempProgram);            }

否则，list中的每一项都要引用同样的对象，那样的话总是显示你最后一次输入的数据。

解决方案二：
每一次遍历，要创建一个新的对象，才可以。需要

if (json_data.getString(""company"") != null) {                tempProgram = new CustomerList();                tempProgram.setCompanyName(json_data.getString(""company""));                tempProgram.setID(json_data.getString(""id""));                fetchDatefromID.add(i tempProgram);        }

这样写。