title: onDateChanged method does not seem to work
body: <p>this is my first post and I am trying to create a very simple tasker app, however I am having issues with (what seems to be) the onDateChanged method. It seems that it does not implement the changes even though the dialog pops up normally. There are no errors in the log and i double checked various solutions with similar functionalities, but i could not find something relevant. (minSDK 16, Target 21)</p>
  
  <p>Thanks a lot in advance and I am sorry if it is something obvious.</p>
  
  <p><div class="snippet" data-lang="js" data-hide="false">
  <div class="snippet-code">
  <pre class="snippet-code-js lang-js prettyprint-override"><code> 
  public class DatePickerFragment extends DialogFragment {
  
      public static final String EXTRA_DATE = "thanoschatz.com.annastodolist.date";
  
      private Date mDate;
  
      public static DatePickerFragment newInstance(Date mDate) {
          Bundle args = new Bundle();
          args.putSerializable(EXTRA_DATE, mDate);
  
          DatePickerFragment fragment = new DatePickerFragment();
          fragment.setArguments(args);
  
          return fragment;
      }
  
      @Override
      public Dialog onCreateDialog(Bundle savedInstanceState) {
          mDate = (Date) getArguments().getSerializable(EXTRA_DATE);
  
  
          Calendar calendar = Calendar.getInstance();
          calendar.setTime(mDate);
          int year = calendar.get(Calendar.YEAR);
          int month = calendar.get(Calendar.MONTH);
          int day = calendar.get(Calendar.DAY_OF_MONTH);
  
          View v = getActivity().getLayoutInflater().inflate(R.layout.dialog_date, null);
  
          DatePicker datePicker = (DatePicker) v.findViewById(R.id.dialog_date_datepicker);
          datePicker.init(year, month, day, new DatePicker.OnDateChangedListener() {
              @Override
              public void onDateChanged(DatePicker view, int year, int monthOfYear, int dayOfMonth) {
  
                  mDate = new GregorianCalendar(year, monthOfYear, dayOfMonth).getTime();
  
  
                  getArguments().putSerializable(EXTRA_DATE, mDate);
              }
          });
  
          return new AlertDialog.Builder(getActivity())
                  .setView(v) //
                  .setTitle(R.string.date_picker_title) //
                  .setPositiveButton(android.R.string.ok, new DialogInterface.OnClickListener() {
                      @Override
                      public void onClick(DialogInterface dialog, int which) {
                          sendResult(Activity.RESULT_OK);
                      }
                  })
                  .create();
      }
  
      private void sendResult(int resultCode) {
          if (getTargetFragment() == null) return;
  
          Intent intent = new Intent();
          intent.putExtra(EXTRA_DATE, mDate);
  
          getTargetFragment().onActivityResult(getTargetRequestCode(), resultCode, intent);
      }
  }</code></pre>
  <pre class="snippet-code-html lang-html prettyprint-override"><code> 
  
  public class ToDoFragment extends Fragment {
      public static final String EXTRA_TODO_ID = "thanoschatz.com.annastodolist.todo_id";
      private static final String DIALOG_DATE = "date";
      private static final int REQUEST_DATE = 0;
  
      private ToDo mToDo;
      private EditText mTitleField;
      private Button mDateButton;
      private CheckBox mDoneCheckBox;
  
  
      @Override
      public void onCreate(Bundle savedInstanceState) {
          super.onCreate(savedInstanceState);
          setHasOptionsMenu(true);
          UUID toDoId = (UUID)getArguments().getSerializable(EXTRA_TODO_ID);
          mToDo= ToDoLab.get(getActivity()).getToDo(toDoId);
      }
  
  
  
      @Override
      public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
          View view = inflater.inflate(R.layout.fragment_todo, container, false);
          wireTitleField(view);
          wireDateButton(view);
          wireSolvedCheckBox(view);
          return  view;
      }
  
  
  
  
      @Override
      public void onActivityResult(int requestCode, int resultCode, Intent intent) {
          if (resultCode != Activity.RESULT_OK) {
              return;
          }
          if (requestCode == REQUEST_DATE) {
              Date mDate = (Date)intent.getSerializableExtra(DatePickerFragment.EXTRA_DATE);
              mToDo.setDate(mDate);
             
          }
      }
  
      public ToDoFragment(){
  
      }
  
      
      public static ToDoFragment newInstance(UUID mId) {
          Bundle args = new Bundle();
          args.putSerializable(EXTRA_TODO_ID, mId);
  
          ToDoFragment fragment = new ToDoFragment();
          fragment.setArguments(args);
  
          return fragment;
      }
  
    
  
      private void wireDateButton(View view) {
          SimpleDateFormat dateFormatter = getSimpleDateFormat();
          mDateButton = (Button)view.findViewById(R.id.toDo_date);
          updateDate(dateFormatter);
  
          mDateButton.setOnClickListener(new View.OnClickListener() {
              public void onClick(View view) {
                  FragmentManager fragmentManager = getFragmentManager();
                  DatePickerFragment datePicker = DatePickerFragment.newInstance(mToDo.getDate());
                  datePicker.setTargetFragment(ToDoFragment.this, REQUEST_DATE);
                  datePicker.show(fragmentManager, DIALOG_DATE);
              }
          });
      }
  }</code></pre>
  </div>
  </div>
  </p>