DatePicker.OnDateChangedListener called twice

I'm trying to create an app where the user selects a date from a DatePicker, and then a list is updated with some values.

My GUI looks like this:

    <LinearLayout
    android:id="@+id/linearLayout1"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_gravity="center" >


    <DatePicker
        android:id="@+id/datePicker"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content" />

</LinearLayout>

<LinearLayout
    android:id="@+id/linearLayout2"
    android:layout_width="match_parent"
    android:layout_height="wrap_content" >



   <ListView
        android:id="@+id/list"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_weight="1" >


    </ListView> 
</LinearLayout>

Whereas my DatePicker initialization and handling look as follows:

public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);

    setContentView(R.layout.main);

    datePicker = (DatePicker) findViewById(R.id.datePicker);

    Calendar c = Calendar.getInstance();

    year = c.get(Calendar.YEAR);
    month = c.get(Calendar.MONTH);
    day = c.get(Calendar.DAY_OF_MONTH);

    datePicker.init(year, month, day, dateSetListener);
}

private DatePicker.OnDateChangedListener dateSetListener = new DatePicker.OnDateChangedListener() {

    public void onDateChanged(DatePicker view, int year, int monthOfYear,
            int dayOfMonth) {
         Calendar c = Calendar.getInstance();
         c.set(year, monthOfYear, dayOfMonth);
         System.out.println ("TEST");

    }
};

In CatLog I see that "TEST" string is output twice, each time I play with the +/- buttons on the widget. What could be the problem?

Note: I've "disabled" the list-updating code on purpose, in order to make sure that the problem is not related to the ListView, as in here

When I test my application, method onDateSet called twice after accept the date selection and once when I canceled.

I added a validation in the method onDateSet with parameter view, something like this

@Override
public void onDateSet(DatePicker view, int year, int monthOfYear, int dayOfMonth){
    if (view.isShown()) {
        updateDate(year, monthOfYear, dayOfMonth);
    }
}

I hope you serve

I still haven't managed to find a neat fix. I've rather found a workaround, so the event does not fire twice. The workaround is as follows:

int timesCalled = 1;

private DatePicker.OnDateChangedListener dateSetListener = new DatePicker.OnDateChangedListener() {

public void onDateChanged(DatePicker view, int year, int monthOfYear,
        int dayOfMonth) {
     Calendar c = Calendar.getInstance();
     c.set(year, monthOfYear, dayOfMonth);
     timesCalled += 1;

     if ((timesCalled % 2) == 0) {
        System.out.println ("TEST");
     }

}};

Instead of the onDateSet callback I've overridden onClick method of the DatePickerDialog dialog and handle BUTTON_POSITIVE clicks only.

public static class DatePickerFragment extends DialogFragment {
    @Override
    public Dialog onCreateDialog(Bundle savedInstanceState) {
        final Calendar c = Calendar.getInstance();
        int initialYear = c.get(Calendar.YEAR);
        int initialMonth = c.get(Calendar.MONTH);
        int initialDay = c.get(Calendar.DAY_OF_MONTH);
        return new DatePickerDialog(getActivity(), null, initialYear, initialMonth, initialDay) {
            @Override
            public void onClick(DialogInterface dialog, int which) {
                if (which == BUTTON_POSITIVE) {
                    int year = getDatePicker().getYear();
                    int month = getDatePicker().getMonth();
                    int day = getDatePicker().getDayOfMonth();

                    //TODO: Do your logic here
                }
                super.onClick(dialog, which);
            }
        };
    }
}

The code stays clear but still it's not clear why onDateSet is called twice.