Set first day of week in DatePicker to monday

I have a DatePicker where I disabled the SpinnerView and now only use the CalendarView. But it starts with the sunday and I would like to use monday as the first day of the week. How can I change that? I guessed that the first day would depend on the phones settings but on my swiss phone its still wrong...

I haven't found any set Method or any XML command.

<DatePicker
   android:id="@+id/date_picker"
   android:layout_width="wrap_content"
   android:layout_height="wrap_content"
   android:layout_alignParentLeft="true"
   android:layout_alignParentRight="true" />

and

DatePicker datePicker = (DatePicker)   convertView.findViewById(R.id.date_picker);
datePicker.setSpinnersShown(false);

------------EDIT:------------

I tried to change the locale:

Locale.setDefault(Locale.GERMAN);

But that didn't change anything ether. So I read the android-17.android.widget.DatePicker.java where I found out:

public DatePicker(Context context, AttributeSet attrs, int defStyle) {
  //...  
  // initialization based on locale
        setCurrentLocale(Locale.getDefault());
  //...
}


 /**
 * Sets the current locale.
 *
 * @param locale The current locale.
 */
private void setCurrentLocale(Locale locale) {
    if (locale.equals(mCurrentLocale)) {
        return;
    }

    mCurrentLocale = locale;

    mTempDate = getCalendarForLocale(mTempDate, locale);
    mMinDate = getCalendarForLocale(mMinDate, locale);
    mMaxDate = getCalendarForLocale(mMaxDate, locale);
    mCurrentDate = getCalendarForLocale(mCurrentDate, locale);

    mNumberOfMonths = mTempDate.getActualMaximum(Calendar.MONTH) + 1;
    mShortMonths = new String[mNumberOfMonths];
    for (int i = 0; i < mNumberOfMonths; i++) {
        mShortMonths[i] = DateUtils.getMonthString(Calendar.JANUARY + i,
                DateUtils.LENGTH_MEDIUM);
    }
}

 /**
 * Gets a calenda