錯誤.java.lang.NullPointerException

-1

java class: 
@Override 
     protected String doInBackground(String... params) { 
      InputStream is = null; 
      String result = ""; 

      ArrayList<NameValuePair> nameValuePairs = new ArrayList<NameValuePair>(); 
      nameValuePairs.add(new BasicNameValuePair("","")); 
      HttpClient httpclient = new DefaultHttpClient(); 
      HttpPost httppost = new HttpPost(strURL); 
      try{ 
       httppost.setEntity(new UrlEncodedFormEntity(nameValuePairs)); 
       HttpResponse response = httpclient.execute(httppost); 
       HttpEntity entity = response.getEntity(); 
       is = entity.getContent(); 
       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(); 


       for(int i=0;i<jArray.length();i++){ 
        JSONObject json_data = jArray.getJSONObject(i); 
        String pid=""+json_data.getString("pid"); 
        String region = json_data.getString("region"); 
        String name = json_data.getString("name"); 
        Double longi = json_data.getDouble("longitude"); 
        Double lati = json_data.getDouble("latitude"); 
        //convert double variable to int variable 
        int d1 = (int) (lati * 1E6); 
        int d2 = (int) (longi * 1E6); 
        //convert int variable to String variable: 
        String latitude = ""+ d1; 
        String longitutde = ""+ d2; 
        Toast.makeText(HomePage.this, latitude, Toast.LENGTH_LONG).show(); 
       } 
      } catch(Exception e) 
      { 
       Log.e("log_tag", "Error in http connection " + e.toString()); 
      } 
      try{ 
       jArray = new JSONArray(result); 

      } 
      catch(JSONException e){ 
       Log.e("log_tag", "Error parsing data " + e.toString()); 
      } 
      return null; 

     } 

     @Override 
     protected void onPostExecute(String result) { 
      pDialog.dismiss(); 
     } 
    } 

}

日誌貓：錯誤.java.lang.NullPointerException

11-27 22:57:22.581: E/Trace(1675): error opening trace file: No such file or directory (2) 
11-27 22:57:22.881: D/libEGL(1675): loaded /system/lib/egl/libEGL_emulation.so 
11-27 22:57:22.885: D/(1675): HostConnection::get() New Host Connection established 0xb9087948, tid 1675 
11-27 22:57:22.901: D/libEGL(1675): loaded /system/lib/egl/libGLESv1_CM_emulation.so 
11-27 22:57:22.901: D/libEGL(1675): loaded /system/lib/egl/libGLESv2_emulation.so 
11-27 22:57:23.185: W/EGL_emulation(1675): eglSurfaceAttrib not implemented 
11-27 22:57:23.201: D/OpenGLRenderer(1675): Enabling debug mode 0 
11-27 22:57:27.037: W/EGL_emulation(1675): eglSurfaceAttrib not implemented 
11-27 22:57:29.181: W/EGL_emulation(1675): eglSurfaceAttrib not implemented 
11-27 22:57:29.289: D/dalvikvm(1675): GC_CONCURRENT freed 120K, 3% free 6232K/6400K, paused 6ms+1ms, total 75ms 
11-27 22:57:30.549: E/log_tag(1675): Error in http connection java.lang.NullPointerException

來源

2013-11-27 user2985357

代替在日誌消息使用e.toString（）的，使用格式Log.e（「log_tag」，「錯誤在http連接」，e）;這將打印出堆棧跟蹤。 – panini

你已經在SO上發佈了2個問題，而且你實際上並沒有提供任何真實的描述 - 也許你應該先閱讀規則，然後返回 – Katana24

，無論如何，strUrl會持有什麼樣的價值？這可能只是一個無效的連接 – DigCamara

//你不能在做後臺運行吐司。任何UI操作只會在UI線程中執行。

//從異步任務刪除此以下行

Toast.makeText(HomePage.this, latitude, Toast.LENGTH_LONG).show();

來源

2013-11-28 04:43:27

錯誤.java.lang.NullPointerException

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