CODEWITHSUNDEEP
javaandroidstringbuffer
Marshal Chen
Marshal Chen

Reputation: 2005

"StringBuffer sb = new StringBuffer()" get a null value in Android

I use the code below which in my http get request,but what I get from return is a null.I don't know why.

  public static String getResponseFromGetUrl(String url) throws Exception {

               StringBuffer sb = new StringBuffer();


                try {
                    HttpResponse httpResponse = httpclient.execute(httpRequest);

                    String inputLine = "";

                    if (httpResponse.getStatusLine().getStatusCode() == HttpStatus.SC_OK) {

                        InputStreamReader is = new InputStreamReader(httpResponse
                                .getEntity().getContent());
                        BufferedReader in = new BufferedReader(is);
                        while ((inputLine = in.readLine()) != null) {

                            sb.append(inputLine);
                        }

                        in.close();

                    }
                } catch (Exception e) {
                    e.printStackTrace();
                    return "net_error";         
                } finally {
                    httpclient.getConnectionManager().shutdown();
                }

                return sb.toString();

   }

And what I have use the function is 

  String json_str = HttpUtils.getResponseFromGetUrl("www.xxx.com/start");
   if ((json_str == null)) Log.d("Chen", "lastestTimestap----" + "json_str == null");

And sometimes the Log will be printed.Not always,in fact like 1%.But I don't know why it caused.

Upvotes: 0

Views: 1879

Answers (1)

Peter Lawrey
Peter Lawrey

Reputation: 533530

This code will not produce a "null". There must be more code you are not showing.

If this is all the code you have I suggest you remove the StringBuffer and replace it with

return "";

More likely you have forgetten to mention some code which is doing something like

Object o = null;

sb.append(o); // appears as "null"

EDIT: Based on your update, I would have to assume you are reading a line like "null"

It is highly unlikely you want to discard the newline between each line. I suggest either you append("\n") as well or just record all the text you get without regard for new lines.

BTW Please don't use StringBuffer as its replacement StringBuilder has been around for almost ten years. There is a common misconception that using StringBuffer helps with multi-threading but more often it results in incorrect code because it is very harder, if not impossible to use StringBuffer correctly in a multi-threaded context

Upvotes: 3

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