从onClick执行后台任务时崩溃

Question

片段上的OnClick事件，当我显示Toast消息时它工作正常，但当我尝试执行后台任务时，我的应用程序崩溃了。我在Activity中使用了相同的代码，它的工作正常，如何在按钮单击时在Fragments中启动后台任务。

public class TestFragment extends Fragment implements Button.OnClickListener {
    private Button mButton; //Add at the top of the fragment
    EditText ET_input_first_name, ET_input_last_name, ET_input_email, ET_input_contact, ET_comments ;
    String   first_name, last_name, email , contact , comments;

    public TestFragment() {
    // Required empty public constructor
    }

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
                         Bundle savedInstanceState) {
        // Inflate the layout for this fragment
        //return inflater.inflate(R.layout.fragment_test, container, false);
        // Inflate the layout for this fragment
        //return inflater.inflate(R.layout.fragment_test, container, false);

        View view = null;
        view = inflater.inflate(R.layout.fragment_test, container, false);

        ET_input_first_name = (EditText)view.findViewById(R.id.input_first_name);
        ET_input_last_name = (EditText)view.findViewById(R.id.input_last_name);
        ET_input_email = (EditText)view.findViewById(R.id.input_email);
        ET_input_contact = (EditText)view.findViewById(R.id.input_contact);
        ET_comments = (EditText)view.findViewById(R.id.comments);

        //mButton = (Button) view.findViewById(R.id.btn_test_drive);
        //mButton.setOnClickListener(this);

        Button b = (Button) view.findViewById(R.id.btn_test_drive);
        b.setOnClickListener(this);

        return view;
    }

    @Override
    public void onClick(View view) {

        first_name  =  ET_input_first_name.getText().toString();
        last_name   =  ET_input_last_name.getText().toString();
        email       =  ET_input_email.getText().toString();
        contact     =  ET_input_contact.getText().toString();
        comments    =  ET_comments.getText().toString();

        String  method = "TestDrive_Submit";
        BackgroundTestDriveTask backgroundTestDriveTask = new BackgroundTestDriveTask(this);
        backgroundTestDriveTask.execute(method, first_name, last_name, email, contact, comments );
        //Toast toast = Toast.makeText(getActivity(), "Submmit button Clicked! Again", Toast.LENGTH_SHORT);
        //toast.show();
    }


}

  

以下是BackgroundTestDriveTask类的代码

public class BackgroundTestDriveTask extends AsyncTask < String, Void, String > {
    pick_drop ctx;
    BackgroundTestDriveTask(View.OnClickListener ctx) {
      this.ctx = (pick_drop) ctx;
    }
    Override protected void onPreExecute() {
      super.onPreExecute();
    }

    protected String doInBackground(String...params) {
      String TestDrive_url = "torcentemotors.com/app/test_drive.php";;
      String method = params[0];
      if (method.equals("TestDrive_Submit")) {
        String s_f_name = params[1];
        String s_l_name = params[2];
        String s_email = params[3];
        String s_contact = params[4];
        String s_comment = params[5];
        try {
          URL url = new URL(TestDrive_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("f_name", "UTF-8") + "=" + URLEncoder.encode(s_f_name, "UTF-8") + "&" + URLEncoder.encode("l_name", "UTF-8") + "=" + URLEncoder.encode(s_l_name, "UTF-8") + "&" + URLEncoder.encode("email", "UTF-8") + "=" + URLEncoder.encode(s_email, "UTF-8") + "&" + URLEncoder.encode("contact", "UTF-8") + "=" + URLEncoder.encode(s_contact, "UTF-8") + "&" + URLEncoder.encode("comments", "UTF-8") + "=" + URLEncoder.encode(s_comment, "UTF-8");
          bufferedWriter.write(data);
          bufferedWriter.flush();
          bufferedWriter.close();
          OS.close();
          InputStream IS = httpURLConnection.getInputStream();
          IS.close();
          return "ThankYou";
    }
}

Answer 1

public class BackgroundTestDriveTask extends AsyncTask<String, Void, String > {
pick_drop ctx;
BackgroundTestDriveTask (View.OnClickListener ctx ) {
        this.ctx = (pick_drop) ctx;
}
@Override
protected void onPreExecute() {
    super.onPreExecute();
}
@Override
protected String doInBackground(String... params) {
    String TestDrive_url = "http://torcentemotors.com/app/test_drive.php";
    String method = params[0];
    if(method.equals("TestDrive_Submit")) {
        String s_f_name    =   params[1];
        String s_l_name    =   params[2];
        String s_email     =   params[3];
        String s_contact   =   params[4];
        String s_comment   =   params[5];
        try {
            URL url = new URL(TestDrive_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("f_name", "UTF-8")+"="+URLEncoder.encode(s_f_name, "UTF-8")+"&"+
                        URLEncoder.encode("l_name", "UTF-8")+"="+URLEncoder.encode(s_l_name, "UTF-8")+"&"+
                        URLEncoder.encode("email", "UTF-8")+"="+URLEncoder.encode(s_email, "UTF-8")+"&"+
                        URLEncoder.encode("contact", "UTF-8")+"="+URLEncoder.encode(s_contact, "UTF-8")+"&"+
                        URLEncoder.encode("comments", "UTF-8")+"="+URLEncoder.encode(s_comment, "UTF-8");

                bufferedWriter.write(data);
                bufferedWriter.flush();
                bufferedWriter.close();
                OS.close();

            InputStream IS = httpURLConnection.getInputStream();
            IS.close();
            return "ThankYou";

        } catch (MalformedURLException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }


    }



    return null;
}

@Override
protected void onProgressUpdate(Void... values) {
    super.onProgressUpdate(values);
}

@Override
protected void onPostExecute(String result) {
    //Toast.makeText(,result, Toast.LENGTH_LONG).show();
    //Toast.makeText(ctx,result, Toast.LENGTH_LONG).show();
    //super.onPostExecute(aVoid);
}

}