在4.2.2版本号上调用系统的DatePickerDialog，发现点击确定时系统调用onDateSet（）两次，须要过滤当中的一次。

Calendar mCalendar = Calendar.getInstance();
mCalendar.add(Calendar.DAY_OF_YEAR, 1);
final DatePickerDialog dateDialog = new DatePickerDialog(this, new DatePickerDialog.OnDateSetListener() {
    boolean mFired = false;
    public void onDateSet(final DatePicker view, final int year, final int monthOfYear, final int dayOfMonth) {
        Log.i("PEW PEW", "Double fire check");
        if (mFired == true) {
            Log.i("PEW PEW", "Double fire occured. Silently-ish returning");
            return;
        } else {
            //first time mFired
            mFired = true;
        }
        //Normal date picking logic goes here
    }
}, mCalendar.get(Calendar.YEAR), mCalendar.get(Calendar.MONTH), mCalendar.get(Calendar.DAY_OF_MONTH));
dateDialog.show();

參考：https://code.google.com/p/android/issues/detail?id=64895