Ошибка преобразования результата java.lang.NullPointerException: lock == null

Question

Я новичок в разработке приложения для Android. Я прочитал много связанных сообщений относительно вопроса, который я задавал, но советы или решения с поста не решили мою проблему. (В поисках решения для уже неделю, очень нужна помощь для того, чтобы приступить к моему проекту) Спасибо много ...

 

    import java.util.ArrayList; 
    import java.util.HashMap; 
    import java.util.List; 

    import org.apache.http.NameValuePair; 
    import org.apache.http.message.BasicNameValuePair; 
    import org.json.JSONArray; 
    import org.json.JSONException; 
    import org.json.JSONObject; 

    import com.example.aroma.slidingmenu.listener.JSONParser; 
    import android.app.ListFragment; 
    import android.app.ProgressDialog; 
    import android.content.Intent; 
    import android.os.AsyncTask; 
    import android.os.Bundle; 
    import android.os.Handler; 
    import android.util.Log; 
    import android.view.LayoutInflater; 
    import android.view.View; 
    import android.view.ViewGroup; 
    import android.widget.AdapterView; 
    import android.widget.AdapterView.OnItemSelectedListener; 
    import android.widget.ListAdapter; 
    import android.widget.ListView; 
    import android.widget.SimpleAdapter; 
    import android.widget.TextView; 
    import android.widget.Toast; 

    public class ResultListFragment extends ListFragment { 

     TextView resultView; 


    public ResultListFragment(){} 

     //progress dialog 
     private ProgressDialog pDialog; 

     //creating JSON Parser object 
     JSONParser jParser = new JSONParser(); 

     ArrayList> customerList; 

     //url to get the customer list 
     private static String url_search="http://192.168.1.3:80/test/getAllCustomers.php"; 

     //JSON Node names 
     private static final String TAG_SUCCESS="success"; 
     private static final String TAG_CUSTOMER="customers"; 
     private static final String TAG_FNAME="FirstName"; 
     private static final String TAG_LNAME="LastName"; 
     private static final String TAG_AGE="Age"; 
     private static final String TAG_MOBILE="Mobile"; 

     //product JSONArray 
     JSONArray customers=null; 
     //search key value 
     public String searchKey; 


     @Override 
     public View onCreateView(LayoutInflater inflater, ViewGroup container, 
       Bundle savedInstanceState) { 

      View rootView = inflater.inflate(R.layout.activity_searchresult_list, container, false); 

      Toast.makeText(getActivity(),"Search result in listview",Toast.LENGTH_LONG).show(); 

      Intent intent = getActivity().getIntent(); 
      searchKey = intent.getStringExtra("message"); 
      //Toast.makeText(getActivity(), searchKey, Toast.LENGTH_LONG).show(); 

      //hshmap for listview 
      customerList= new ArrayList>(); 


      //Loading customer in background thread 
      new LoadCustomer().execute(); 

      return rootView;  
     } 

     @Override 
     public void onViewCreated (View view, Bundle savedInstanceState) { 

      ListView lv =getListView(); 

      lv.setOnItemSelectedListener(new OnItemSelectedListener(){ 

       @Override 
       public void onItemSelected(AdapterView parent, View view, 
         int position, long id) { 
        // TODO Auto-generated method stub 
        String iid=((TextView)view.findViewById(R.id.FirstName)).getText().toString(); 
       } 

       @Override 
       public void onNothingSelected(AdapterView parent) { 
        // TODO Auto-generated method stub 

       } 
      }); 
     } 

     /** 
     * Background Async Task to load customers by making HTTP request 
     * */ 
     class LoadCustomer extends AsyncTask{ 
      /** 
      * Before starting background thread show progress dialog 
      * */ 
      @Override 
      protected void onPreExecute(){ 
       super.onPreExecute(); 
       pDialog=new ProgressDialog(getActivity()); //pDialog=new ProgressDialog(ResultListFragment.this); 
       pDialog.setMessage("Loading customers. Please wait..."); 
       pDialog.setIndeterminate(false); 
       pDialog.setCancelable(false); 
       pDialog.show(); 
      } 

      /** 
      * getting customers url 
      * **/ 
      protected String doInBackground(String... args){ 
       //Building Parameters 
       List params= new ArrayList(); 
       //value captured from previous intent 
       params.add(new BasicNameValuePair("FirstName", searchKey)); 
       //getting JSON string from url 
       JSONObject json = jParser.makeHttpRequest(url_search, "GET", params); 
       //check your log cat for JSON response 
       Log.d("Search customer", json.toString()); 

       try{ 
        //checking for SUCCESS TAG 
        int success=json.getInt(TAG_SUCCESS); 

        if(success==1){ 
         //product found 
         //Getting array of products 
         customers=json.getJSONArray(TAG_CUSTOMER); 

         //looping through all products 
         for(int i=0;i map=new HashMap(); 

          //adding each child node to HashMap key =>value 
          map.put(TAG_FNAME, fname); 
          map.put(TAG_LNAME, lname); 
          map.put(TAG_AGE, age); 
          map.put(TAG_MOBILE, mobile); 

          //adding HashList to ArrayList 
          customerList.add(map); 
         } 
        }else{ 
          //no customer found 
          //do sth 
         Handler handler = new Handler(getActivity().getMainLooper()); 
         handler.post(new Runnable(){ 
          public void run(){ 
           Toast.makeText(getActivity(),"no customer found" ,Toast.LENGTH_LONG).show(); 
          } 
         }); 
         } 
        }catch (JSONException e){ 
         e.printStackTrace(); 
        } 

        //return "success"; 
        return null; 
       } 

      /** 
      * After completing background task dismiss the progress dialog 
      * **/ 
      protected void onPostExecute(String file_url){ 
       //dimiss the dialog after getting the related customer 
       pDialog.dismiss(); 
       getActivity().runOnUiThread(new Runnable(){ 
        public void run(){ 
         /** 
         * updating parsed JSON data into ListView 
         * **/ 
         ListAdapter adapter =new SimpleAdapter(
           getActivity(), customerList, 
           R.layout.list_item, new String[]{ TAG_FNAME, TAG_LNAME, TAG_AGE, TAG_MOBILE}, 
           new int[]{R.id.FirstName,R.id.LastName,R.id.Age,R.id.Mobile}); 
          //updating listview 
          setListAdapter(adapter); 
        } 
       }); 

      } 

     } 


    } 

JSONParser.java

 

    package com.example.aroma.slidingmenu.listener; 

    import java.io.BufferedReader; 
    import java.io.IOException; 
    import java.io.InputStream; 
    import java.io.InputStreamReader; 
    import java.io.UnsupportedEncodingException; 
    import java.util.List;http://stackoverflow.com/editing-help 

    import org.apache.http.HttpEntity; 
    import org.apache.http.HttpResponse; 
    import org.apache.http.NameValuePair; 
    import org.apache.http.client.ClientProtocolException; 
    import org.apache.http.client.entity.UrlEncodedFormEntity; 
    import org.apache.http.client.methods.HttpGet; 
    import org.apache.http.client.methods.HttpPost; 
    import org.apache.http.client.utils.URLEncodedUtils; 
    import org.apache.http.impl.client.DefaultHttpClient; 
    import org.apache.http.util.EntityUtils; 
    import org.json.JSONException; 
    import org.json.JSONObject; 

    import android.util.Log; 

    public class JSONParser { 

     static InputStream is = null; 
     static JSONObject jObj = null; 
     static String json = ""; 

     // constructor 
     public JSONParser() { 

     } 

     // function get json from url 
     // by making HTTP POST or GET mehtod 
     public JSONObject makeHttpRequest(String url, String method, 
       List params) { 

      // Making HTTP request 
      try { 

       // check for request method 
       if(method.equals("POST")){ 
        // request method is POST 
        // defaultHttpClient 
        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(); 

       }else if(method.equals("GET")){ 
        // request method is 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(); 

        String all=EntityUtils.toString(httpEntity); 
        Log.d("response",all); 
       }   


      } 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 parse the string to a JSON object 
      try { 
       jObj = new JSONObject(json); 
      } catch (JSONException e) { 
       Log.e("JSON Parser", "Error parsing data " + e.toString()); 
      } 

      // return JSON String 
      return jObj; 

     }  
    } 

getAllCustomers.php

 


    $response = array(); 
    $con = mysql_connect("localhost","root",""); 
    if (!$con) 
     { 
     die('Could not connect: ' . mysql_error()); 
     } 
    mysql_select_db("testdatabase", $con); 

    $FirstName=$_GET["FirstName"]; 
    $result = mysql_query("SELECT * FROM customer where FirstName like '%$FirstName%' "); 


    if(mysql_num_rows($result)>0){ 
     // looping through all results 
     // products node 
     $response["customers"] = array(); 

     while ($row = mysql_fetch_array($result)) { 
      // temp user array 
      $customers = array(); 
      $customers["FirstName"] = $row["FirstName"]; 
      $customers["LastName"] = $row["LastName"]; 
      $customers["Age"] = $row["Age"]; 
      $customers["Mobile"] = $row["Mobile"]; 

      // push single product into final response array 
      array_push($response["customers"], $customers); 
    } 
    // success 
     $response["success"] = 1; 
     // echoing JSON response 
     echo json_encode($response); 
    } else { 
     // no products found 
     $response["success"] = 0; 
     $response["message"] = "No products found"; 

     // echo no users JSON 
     echo json_encode($response); 
    } 

Ошибка, что я спасен от LogCat:

 

    02-12 17:17:50.599: E/Buffer Error(13636): Error converting result java.lang.NullPointerException: lock == null 
    02-12 17:17:50.599: E/JSON Parser(13636): Error parsing data org.json.JSONException: End of input at character 0 of 
    02-12 17:17:50.604: E/AndroidRuntime(13636): FATAL EXCEPTION: AsyncTask #4 
    02-12 17:17:50.604: E/AndroidRuntime(13636): java.lang.RuntimeException: An error occured while executing doInBackground() 
    02-12 17:17:50.604: E/AndroidRuntime(13636): at android.os.AsyncTask$3.done(AsyncTask.java:299) 
    02-12 17:17:50.604: E/AndroidRuntime(13636): at java.util.concurrent.FutureTask.finishCompletion(FutureTask.java:352) 
    02-12 17:17:50.604: E/AndroidRuntime(13636): at java.util.concurrent.FutureTask.setException(FutureTask.java:219) 
    02-12 17:17:50.604: E/AndroidRuntime(13636): at java.util.concurrent.FutureTask.run(FutureTask.java:239) 
    02-12 17:17:50.604: E/AndroidRuntime(13636): at android.os.AsyncTask$SerialExecutor$1.run(AsyncTask.java:230) 
    02-12 17:17:50.604: E/AndroidRuntime(13636): at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1080) 
    02-12 17:17:50.604: E/AndroidRuntime(13636): at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:573) 
    02-12 17:17:50.604: E/AndroidRuntime(13636): at java.lang.Thread.run(Thread.java:838) 
    02-12 17:17:50.604: E/AndroidRuntime(13636): Caused by: java.lang.NullPointerException 
    02-12 17:17:50.604: E/AndroidRuntime(13636): at com.example.aroma.slidingmenu.ResultListFragment$LoadCustomer.doInBackground(ResultListFragment.java:136) 
    02-12 17:17:50.604: E/AndroidRuntime(13636): at com.example.aroma.slidingmenu.ResultListFragment$LoadCustomer.doInBackground(ResultListFragment.java:1) 
    02-12 17:17:50.604: E/AndroidRuntime(13636): at android.os.AsyncTask$2.call(AsyncTask.java:287) 
    02-12 17:17:50.604: E/AndroidRuntime(13636): at java.util.concurrent.FutureTask.run(FutureTask.java:234) 
    02-12 17:17:50.604: E/AndroidRuntime(13636): ... 4 more 

Answer 1

Try вызов AsyncTask в onActivityCreated

@Override 
    public View onCreateView(LayoutInflater inflater, ViewGroup container, 
      Bundle savedInstanceState) { 

     View rootView = inflater.inflate(R.layout.activity_searchresult_list, container, false);   

     return rootView;  
    } 

@Override 
public void onActivityCreated(Bundle savedInstanceState) { 
    super.onActivityCreated(savedInstanceState); 

     Toast.makeText(getActivity(),"Search result in listview",Toast.LENGTH_LONG).show(); 

     Intent intent = getActivity().getIntent(); 
     searchKey = intent.getStringExtra("message"); 
     //Toast.makeText(getActivity(), searchKey, Toast.LENGTH_LONG).show(); 

     //hshmap for listview 
     customerList= new ArrayList>(); 


     //Loading customer in background thread 
     new LoadCustomer().execute(); 

}