Avoid force Close Error when Server is not responding

https://stackoverflow.com/questions/21181769

29-09-2022
|

Question

In my application user has to login to access the app.Login details are stored inMysql database and php files.Often app was closed due to apache server and it shows following details in my logcat,

[<!DOCTYPE HTML PUBLIC "-//IETF//DTD HTML 2.0//EN">
01-17 08:59:01.935: I/tagconvertstr1(1160): <html><head>
01-17 08:59:01.935: I/tagconvertstr1(1160): <title>404 Not Found</title>
01-17 08:59:01.935: I/tagconvertstr1(1160): </head><body>
01-17 08:59:01.935: I/tagconvertstr1(1160): <h1>Not Found</h1>
01-17 08:59:01.935: I/tagconvertstr1(1160): <p>The requested URL     /bcreasearchT/Service/loginresponse.php was not found on this server.</p>
01-17 08:59:01.935: I/tagconvertstr1(1160): <hr>
01-17 08:59:01.935: I/tagconvertstr1(1160): <address>Apache/2.2.15 (CentOS) Server at www.medsmonit.com Port 80</address>
01-17 08:59:01.935: I/tagconvertstr1(1160): </body></html>
01-17 08:59:01.935: I/tagconvertstr1(1160): ]
01-17 08:59:01.945: E/JSON Parser(1160): Error parsing data org.json.JSONException: Value <!DOCTYPE of type java.lang.String cannot be converted to JSONObject
01-17 08:59:01.955: I/Choreographer(1160): Skipped 40 frames!  The application may be doing too much work on its main thread.
01-17 08:59:01.965: I/tagconvertstr3(1160): [null]
01-17 08:59:01.965: W/dalvikvm(1160): threadid=14: thread exiting with uncaught exception (group=0x40a71930)
01-17 08:59:01.995: I/Choreographer(1160): Skipped 31 frames!  The application may be doing too much work on its main thread.
01-17 08:59:02.025: E/AndroidRuntime(1160): FATAL EXCEPTION: AsyncTask #3
01-17 08:59:02.025: E/AndroidRuntime(1160): java.lang.RuntimeException: An error occured while executing doInBackground()
01-17 08:59:02.025: E/AndroidRuntime(1160):     at android.os.AsyncTask$3.done(AsyncTask.java:299)
01-17 08:59:02.025: E/AndroidRuntime(1160):     at java.util.concurrent.FutureTask.finishCompletion(FutureTask.java:352)
01-17 08:59:02.025: E/AndroidRuntime(1160):     at java.util.concurrent.FutureTask.setException(FutureTask.java:219)
01-17 08:59:02.025: E/AndroidRuntime(1160):     at java.util.concurrent.FutureTask.run(FutureTask.java:239)
01-17 08:59:02.025: E/AndroidRuntime(1160):     at android.os.AsyncTask$SerialExecutor$1.run(AsyncTask.java:230)
01-17 08:59:02.025: E/AndroidRuntime(1160):     at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1080)
01-17 08:59:02.025: E/AndroidRuntime(1160):     at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:573)
01-17 08:59:02.025: E/AndroidRuntime(1160):     at java.lang.Thread.run(Thread.java:856)
01-17 08:59:02.025: E/AndroidRuntime(1160): Caused by: java.lang.NullPointerException
01-17 08:59:02.025: E/AndroidRuntime(1160):     at com.example.sms.LoginActivity$AttemptLogin.doInBackground(LoginActivity.java:280)
01-17 08:59:02.025: E/AndroidRuntime(1160):     at com.example.sms.LoginActivity$AttemptLogin.doInBackground(LoginActivity.java:1)
01-17 08:59:02.025: E/AndroidRuntime(1160):     at android.os.AsyncTask$2.call(AsyncTask.java:287)
01-17 08:59:02.025: E/AndroidRuntime(1160):     at java.util.concurrent.FutureTask.run(FutureTask.java:234)
01-17 08:59:02.025: E/AndroidRuntime(1160):     ... 4 more

How can I rectify it?Can anyone help me!

UPDATE:

This my aynctask code,

 class AttemptLogin extends AsyncTask<String, String, String> {
    @Override
    protected void onPreExecute() {
        super.onPreExecute();
        username = (EditText) findViewById(R.id.mobnum);
           passw = (EditText) findViewById(R.id.password);
           uname = username.getText().toString();

              password = passw.getText().toString();    

        pDialog = new ProgressDialog(LoginActivity.this);
        pDialog.setMessage("VALIDATING USER...");
        pDialog.setIndeterminate(false);
        pDialog.setCancelable(false);
        pDialog.show();
    }

    @Override
    protected String doInBackground(String... params) {


          proInfo.clear();

         List<NameValuePair> params1 = new ArrayList<NameValuePair>();

         params1.add(new BasicNameValuePair("username", uname));
         params1.add(new BasicNameValuePair("pswd", password));

         JsonParser jLogin = new JsonParser();
         JSONObject json = jLogin.makeHttpRequest(url,"POST", params1);


         Log.i("tagconvertstr3", "["+json+"]");
         try
         {

             JSONObject jUser = json.getJSONObject(TAG_SRESL);
             userid = jUser.getString(TAG_USERID );

             successL = jUser.getString(TAG_SUCCESS1);

             proInfo.add(userid);


             }

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

         }


        return null;
    }

   protected void onPostExecute(String file_url) {


       if(successL.equalsIgnoreCase("Yes"))
       {
           usrname=uname;
           new ViewProfile().execute();

       }

       else{
         final Dialog dialog = new Dialog(context);
             dialog.setContentView(R.layout.custom_dialog);
             dialog.setTitle("Login Failed");
             dialog.setCancelable(false);
             dialog.setCanceledOnTouchOutside(false);
             TextView txt = (TextView) dialog.findViewById(R.id.errorlog);
              txt.setText("Incorrect username or password!");
              Button dialogButton = (Button) dialog.findViewById(R.id.release);
              dialogButton.setOnClickListener(new OnClickListener() {
                  public void onClick(View vd) {
                       dialog.dismiss();

            }
            });
              dialog.show();
              pDialog.dismiss();
          }
        }


    }

This is my json parser class,

  public JSONObject makeHttpRequest(String url, String method,
        List<NameValuePair> params) {


    try {

        if(method.equalsIgnoreCase("POST")){


            DefaultHttpClient httpClient = new DefaultHttpClient();
            HttpPost httpPost = new HttpPost(url);

            httpPost.setEntity(new UrlEncodedFormEntity(params));

            HttpResponse httpResponse = httpClient.execute(httpPost);
            HttpEntity httpEntity = httpResponse.getEntity();
            is = httpEntity.getContent();

            System.out.println(is);

            System.out.println("getting the content");

        }else if(method.equalsIgnoreCase("GET")){

            DefaultHttpClient httpClient = new DefaultHttpClient();
            String paramString = URLEncodedUtils.format(params, "utf-8");
            url += "?" + paramString;
            HttpGet httpGet = new HttpGet(url);

            HttpResponse httpResponse = httpClient.execute(httpGet);
            HttpEntity httpEntity = httpResponse.getEntity();
            is = httpEntity.getContent();
        }           

    } catch (UnsupportedEncodingException e) {
        e.printStackTrace();
    } catch (ClientProtocolException e) {
        e.printStackTrace();
    } catch (IOException e) {
        e.printStackTrace();
    }


    System.out.println("getting  all the values ");

    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();

        json = sb.toString();    


    } catch (Exception e) {
        Log.e("Buffer Error", "Error converting result " + e.toString());
    }


    try {

        Log.i("tagconvertstr1", "["+json+"]");

        jsonObject = new JSONObject(json);
          System.out.println("json object parse finished");

        Log.i("tagconvertstr2","["+json+"]");




    } catch (JSONException e) {
        Log.e("JSON Parser", "Error parsing data " + e.toString());
    }




    return jsonObject;

}






public JSONObject getJSONFromUrl(String url) {

            try {

                DefaultHttpClient httpClient = new DefaultHttpClient();
                HttpPost httpPost = new HttpPost(url);

                HttpResponse httpResponse = httpClient.execute(httpPost);
                HttpEntity httpEntity = httpResponse.getEntity();
                is = httpEntity.getContent();           

            } catch (UnsupportedEncodingException e) {
                e.printStackTrace();
            } catch (ClientProtocolException e) {
                e.printStackTrace();
            } catch (IOException e) {
                e.printStackTrace();
            }
            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();
                json = sb.toString();
            } catch (Exception e) {
                Log.e("Buffer Error", "Error converting result " + e.toString());
            }

            try {
                Log.i("tagconvertstr", "["+json+"]");
                jsonObject = new JSONObject(json);
                Log.i("tagconvertstr", "["+json+"]");

            } catch (JSONException e) {
                Log.e("JSON Parser", "Error parsing data " + e.toString());
            }


            return jsonObject;

}

Solution

JSONObject jUser = json.getJSONObject(TAG_SRESL);//This is mt 280th line

Your json is null. Start debugging. jLogin.makeHttpRequest(url,"POST", params1); is returning null.

Also move (it is better)

 username = (EditText) findViewById(R.id.mobnum);
 passw = (EditText) findViewById(R.id.password);

to onCreate

You can pass params directly to asynctask doInbackground

 new AttemptLogin().execute(username.getText().toString(),passw.getText().toString());

Then in doInbackground()

 //String... params 
 params[0] is username
 params[1]  is password

You are also missing

@Override
protected void onPostExecute(String file_url) {
super.onPostExecute(file_url);

OTHER TIPS

i think you should check the response code from the server and act based on that because it seams that the json creation fails and maybe that causes the nullpointer.

Kepp condition before using json object. Replace your code in doInBackground.

try {
    if(json != null){
        JSONObject jUser = json.getJSONObject(TAG_SRESL);
        userid = jUser.getString(TAG_USERID );
        successL = jUser.getString(TAG_SUCCESS1);
        proInfo.add(userid);
    }
}catch(JSONException e) {
    e.printStackTrace();
}

Check here string before checking the equalsIgnoreCase, Replace your onPostExecute code.

if(successL != null && successL.equalsIgnoreCase("Yes")) {
    usrname=uname;
    new ViewProfile().execute();
}

Please try it.

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