在列表中添加值后，无法检索出来

原问题来自于CSDN问答频道，更多解决方案见：http://ask.csdn.net/questions/1879

问题描述：

在一个列表中我使用add(int,Object)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(
                is, "iso-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。