HTTP POST successful, but the AsyncTask returning NullPointerException?

Question

I have input form in my Android application the inputed data will saved to online database

now I can save the data and upload the picture using AsyncTask.

the data were uploaded successfully, but the AsyncTask returning java.lang.NullPointerException

here's my AsyncTask class:

private class SaveAsetData extends AsyncTask<String, Void, String>{

    ProgressDialog pd = new ProgressDialog(FormAsetTambah.this);

    BufferedReader in = null;

    final TextView errorText = (TextView) findViewById(R.id.error_text);

    protected void onPreExecute(){
        pd.setMessage(Functions.GetString(getApplicationContext(), R.string.progress_dialog_loading));
        pd.show();
    }

    @Override
    protected String doInBackground(String... arg0) {

        try {

            String URL_DESTINATION = URLVariables.get_base_url()+"aset_tambah_pic.php";

            Bitmap bm = BitmapFactory.decodeFile(arg0[7]);
            ByteArrayOutputStream bos = new ByteArrayOutputStream();
            bm.compress(CompressFormat.JPEG, 50, bos);

            HttpClient httpClient = CustomHttpClient.getHttpClient();
            HttpPost postRequest = new HttpPost(URL_DESTINATION);           

            MultipartEntity reqEntity = new MultipartEntity(
            HttpMultipartMode.BROWSER_COMPATIBLE);
            reqEntity.addPart("uploadedfile", new FileBody(new File(arg0[7])));
            reqEntity.addPart("nama", new StringBody(arg0[0]));
            reqEntity.addPart("detail", new StringBody(arg0[1]));
            reqEntity.addPart("keterangan", new StringBody(arg0[2]));
            reqEntity.addPart("longitude", new StringBody(arg0[3]));
            reqEntity.addPart("latitude", new StringBody(arg0[4]));
            reqEntity.addPart("kategori", new StringBody(arg0[5]));
            reqEntity.addPart("daerah", new StringBody(arg0[6]));
            postRequest.setEntity(reqEntity);

            HttpResponse response = httpClient.execute(postRequest);

            in = new BufferedReader(new InputStreamReader(response.getEntity().getContent()));

            StringBuffer sb = new StringBuffer("");
            String line = "";
            String NL = System.getProperty("line.separator");

            while((line = in.readLine()) != null){
                sb.append(line+NL);
            }

            in.close();

            String result = sb.toString();

            return result;

        }catch(Exception e){            
            return e.toString();
        }

    }

    protected void onPostExecute(String result){

        try{

            String output = result.toString().trim();
            error_text.setText(output);

            if(output.equals("1")){
                Functions.MakeToast(getApplicationContext(), ERR_SAVED);
                Intent daftarAset = new Intent(getApplicationContext(), DaftarAset.class);
                startActivity(daftarAset);
                finish();
            }else if(output.equals("2")){
                Functions.MakeToast(getApplicationContext(), ERR_QUERY);
            }else{
                Functions.MakeToast(getApplicationContext(), ERR_HTTPFAIL);
            }

        }catch(Exception e){
            Functions.MakeToast(getApplicationContext(), "onPostExecute fail : "+e.toString()); // it failed here
        }
        pd.dismiss();
    }

}

do you know where's my fault? or any advice/solution to make it better?

Update

Here's my exception on logcat

07-27 21:54:09.222: WARN/System.err(17600): java.lang.NullPointerException
07-27 21:54:09.222: WARN/System.err(17600):     at com.ngimagrid.nigmago.FormAsetTambah$SaveData.onPostExecute(FormAsetTambah.java:567)
07-27 21:54:09.222: WARN/System.err(17600):     at com.ngimagrid.nigmago.FormAsetTambah$SaveData.onPostExecute(FormAsetTambah.java:1)
07-27 21:54:09.222: WARN/System.err(17600):     at android.os.AsyncTask.finish(AsyncTask.java:417)
07-27 21:54:09.222: WARN/System.err(17600):     at android.os.AsyncTask.access$300(AsyncTask.java:127)
07-27 21:54:09.222: WARN/System.err(17600):     at android.os.AsyncTask$InternalHandler.handleMessage(AsyncTask.java:429)
07-27 21:54:09.222: WARN/System.err(17600):     at android.os.Handler.dispatchMessage(Handler.java:99)
07-27 21:54:09.222: WARN/System.err(17600):     at android.os.Looper.loop(Looper.java:123)
07-27 21:54:09.222: WARN/System.err(17600):     at android.app.ActivityThread.main(ActivityThread.java:3687)
07-27 21:54:09.222: WARN/System.err(17600):     at java.lang.reflect.Method.invokeNative(Native Method)
07-27 21:54:09.222: WARN/System.err(17600):     at java.lang.reflect.Method.invoke(Method.java:507)
07-27 21:54:09.222: WARN/System.err(17600):     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:842)
07-27 21:54:09.222: WARN/System.err(17600):     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:600)
07-27 21:54:09.222: WARN/System.err(17600):     at dalvik.system.NativeStart.main(Native Method)

UPDATE

here's my server side code:

<?php

    require_once("functions.php");

    $nama = trim($_POST['nama']);
    $detail = trim($_POST['detail']);
    $keterangan = trim($_POST['keterangan']);
    $longitude= trim($_POST['longitude']);
    $latitude = trim($_POST['latitude']);

    $kategori = trim($_POST['kategori']);
    $daerah = trim($_POST['daerah']);

    $target_path = "images/";
    $file_tmp_name = $_FILES['uploadedfile']['tmp_name'];
    $file_name = str_replace(array(" ","-"), "_", strtolower(basename($_FILES['uploadedfile']['name'])));
    $target_path = $target_path.$file_name; 


    if(empty($nama) || empty($detail) || empty($keterangan) || empty($longitude) || empty($latitude) || empty($kategori) || empty($daerah) || empty($file_tmp_name)){

        echo "5";

    }else{

        openDB();

        $get_id_kategori = mysql_fetch_array(mysql_query("SELECT `id_kategori` FROM `aset_kategori` WHERE `kategori`='$kategori'"));
        $get_id_daerah = mysql_fetch_array(mysql_query("SELECT `id_daerah` FROM `aset_daerah` WHERE `daerah`='$daerah'"));

        $tanggal = date("Y-m-d H:i:s");

        $sql = "INSERT INTO  `aset` (`id_aset` ,`id_daerah` ,`id_kategori` ,`nama` ,`detail` ,`longitude` ,`latitude` ,`keterangan` ,`status` ,`tanggal`)
                    VALUES (NULL ,  '$get_id_daerah[0]',  '$get_id_kategori[0]',  '$nama',  '$detail', '$longitude',  '$latitude',  '$keterangan',  'Y',  '$tanggal');";

        if(mysql_query($sql)){
            if(!file_exists($target_path)){
                if(move_uploaded_file($_FILES['uploadedfile']['tmp_name'], $target_path)) {

                    $id_aset = mysql_fetch_array(mysql_query("SELECT `id_aset` FROM `aset` ORDER BY `id_aset` DESC LIMIT 1"));
                    mysql_query("INSERT INTO `aset_foto` (`id_foto`, `id_aset`, `foto`) VALUES (NULL, '$id_aset[0]', '$file_name');");  

                    echo "1";   // success          
                } else{         
                    echo "2"; // failed         
                }
            }else{
                echo "3";   // failed
            }
        }else{
            echo "4";   //failed
        }

        closeDB();

    }

?>

if the response equals 1, then the saving proccess was successful

Answer 1

I think I got it. I suggest in your doInBackground() method to return in.readline().trim(); (also try without trimming)

Why? Because in your script you are echo-ing only one character (which may be done even with .read(), so there is no need to iterate through the InputStreamReader object.

In onPostExecute() method, I suggest to Log the result and see what's its with the value, before you do anything.

Answer 2

On open up your GoTo line functionality in your IDE or any descent text editor. Type in 567, and that's the line number that is failing. Unfortunately, without the actual full source we can't tell what line number 567 occurs in this fragment.

The lines that looks suspect of issues could be:

String output = result.toString().trim();
error_text.setText(output);

The result could be null, or toString() could be returning null. error_text could also be null.