MyApp的停在实际设备工作

Question

我的应用程序工作在虚拟设备伟大的，但是当我实际的设备我得到了“我的应用程序停止工作”错误..上运行它，这个错误日志

06-07 12:20:09.022 28371-28371/my.amirul.psm E/AndroidRuntime: FATAL EXCEPTION: main 
java.lang.NullPointerException at  my.amirul.psm.BackgroundTask.onPostExecute(BackgroundTask.java:113) 
at my.amirul.psm.BackgroundTask.onPostExecute(BackgroundTask.java:22) 
at android.os.AsyncTask.finish(AsyncTask.java:631) 
at android.os.AsyncTask.access$600(AsyncTask.java:177) 
at android.os.AsyncTask$InternalHandler.handleMessage(AsyncTask.java:644) 
at android.os.Handler.dispatchMessage(Handler.java:107) 
at android.os.Looper.loop(Looper.java:194) 
at android.app.ActivityThread.main(ActivityThread.java:5391) 
at java.lang.reflect.Method.invokeNative(Native Method) 
at java.lang.reflect.Method.invoke(Method.java:525) 
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:833) 
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:600) 
at dalvik.system.NativeStart.main(Native Method) 

在这是我的后台任务代码...

public class BackgroundTask extends AsyncTask<String,Void,String>{ 

AlertDialog alertDialog; 
Context ctx; 
BackgroundTask(Context ctx) 
{ 
this.ctx = ctx; 
} 
@Override 
protected void onPreExecute() { 
    alertDialog = new AlertDialog.Builder(ctx).create(); 
    alertDialog.setTitle("Login Information......"); 
} 

@Override 
protected String doInBackground(String... params) { 
    String reg_url = "http://10.0.2.2/webapp/register.php"; 
    String login_url = "http://10.0.2.2/webapp/login.php"; 
    String method = params[0]; 
    if(method.equals("register")) 
    { 
    String name = params[1]; 
    String user_name = params[2]; 
    String user_pass = params [3]; 

     try { 
      URL url = new URL(reg_url); 
      HttpURLConnection httpURLConnection =(HttpURLConnection) url.openConnection(); 
      httpURLConnection.setRequestMethod("POST"); 
      httpURLConnection.setDoOutput(true); 
      OutputStream OS = httpURLConnection.getOutputStream(); 
      BufferedWriter bufferedWriter= new BufferedWriter(new OutputStreamWriter(OS,"UTF-8")); 
      String data = URLEncoder.encode("user","UTF-8") + "=" + URLEncoder.encode(name,"UTF-8")+"&"+ 
        URLEncoder.encode("user_name","UTF-8") + "=" + URLEncoder.encode(user_name,"UTF-8")+"&"+ 
        URLEncoder.encode("user_pass","UTF-8") + "=" + URLEncoder.encode(user_pass,"UTF-8"); 

      bufferedWriter.write(data); 
      bufferedWriter.flush(); 
      bufferedWriter.close(); 
      OS.close(); 
      InputStream IS = httpURLConnection.getInputStream(); 
      IS.close(); 
      return "Registration Success..."; 
     } catch (MalformedURLException e) { 
      e.printStackTrace(); 
     } catch (IOException e) { 
      e.printStackTrace(); 
     } 
    } 
    else if (method.equals("login")) 
    { 
     String login_name = params[1]; 
     String login_pass = params[2]; 
     try { 
      URL url = new URL(login_url); 
      HttpURLConnection httpURLConnection =(HttpURLConnection)url.openConnection(); 
      httpURLConnection.setRequestMethod("POST"); 
      httpURLConnection.setDoOutput(true); 
      httpURLConnection.setDoInput(true); 
      OutputStream outputStream = httpURLConnection.getOutputStream(); 
      BufferedWriter bufferedWriter = new BufferedWriter(new OutputStreamWriter(outputStream,"UTF-8")); 
     String data = URLEncoder.encode("login_name","UTF-8")+"="+URLEncoder.encode(login_name,"UTF-8")+"&"+ 
       URLEncoder.encode("login_pass","UTF-8")+"="+URLEncoder.encode(login_pass,"UTF-8"); 
      bufferedWriter.write(data); 
      bufferedWriter.flush(); 
      bufferedWriter.close(); 
      outputStream.close(); 

      InputStream inputStream = httpURLConnection.getInputStream(); 
      BufferedReader bufferedReader = new BufferedReader(new InputStreamReader(inputStream,"iso-8859-1")); 
      String response = ""; 
      String line = ""; 
      while ((line = bufferedReader.readLine())!=null) 
      { 
       response+= line ; 
      } 
      bufferedReader.close(); 
      inputStream.close(); 
      httpURLConnection.disconnect(); 
      return response; 

     } catch (MalformedURLException e) { 
      e.printStackTrace(); 
     } catch (IOException e) { 
      e.printStackTrace(); 
     } 
    } 
    return null; 
} 
@Override 
protected void onPostExecute(String result) { 
    if (result.equals("Registration Success...")) { 
     Toast.makeText(ctx, result, Toast.LENGTH_LONG).show(); 
    } else if(result.contains("Hello")) { 
     Intent i = new Intent(ctx, FormActivity.class); 
     ctx.startActivity(i); 
    } else { 
     alertDialog.setMessage(result); 
     alertDialog.show(); 
    } 
} 
} 

plz帮助我...

Answer 1

事实上，网络不可用，并获得系统与网络连接时为空。在模拟器上，您正在使用系统的网络。我希望它能帮助你。

Answer 2

将您的设备连接到网络或WiFi /数据连接。然后

假设你是在同一个无线网络上...

找到你的本地IP地址（应该是192.168.1.X） - 进入命令提示符，输入“IPCONFIG '得到这个。其中x是服务器机器分配的本地IP地址。 使用您的本地IP地址为您的Android设备连接到您的本地主机。

它为我工作。

注意：访问模拟器上的localhost：10.0.2.2。但是，例如，如果您拥有除XMPP服务器之类的Web服务器以外的其他服务器，则这可能并不总是有效。

这可能会帮助你。

Answer 3

我是唯一一个看到

return null; 

出的每一个如果在doInBackground月底/ else语句？

如果成功了，没关系，因为第一个if语句中有一个return "Registration Success...";，但是如果失败，它将为空，因此为空指针异常。