public class MainActivity extends AppCompatActivity implements CalendarViewPagerFragment.OnPageChangeListener, CalendarViewFragment.OnDateClickListener, CalendarViewFragment.OnDateCancelListener {  private TextView tv_date; private boolean isChoiceModelSingle = false; private List<CalendarDate> mListDate = new ArrayList<>();  @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); tv_date = (TextView) findViewById(R.id.tv_date); initFragment(); }  private void initFragment(){ FragmentManager fm = getSupportFragmentManager(); FragmentTransaction tx = fm.beginTransaction(); // Fragment fragment = new CalendarViewPagerFragment(); Fragment fragment = CalendarViewPagerFragment.newInstance(isChoiceModelSingle); tx.replace(R.id.fl_content, fragment); tx.commit(); }   @Override public boolean onCreateOptionsMenu(Menu menu) { getMenuInflater().inflate(R.menu.menu_im, menu); return true; } @Override public boolean onOptionsItemSelected(MenuItem item) { switch (item.getItemId()) {  case R.id.menu_single:  isChoiceModelSingle = true;  initFragment();  break;  case R.id.menu_multi:  isChoiceModelSingle = false;  initFragment();  break;  default:  break; } return true; } @Override public void OnDateClick(CalendarDate calendarDate) {  int year = calendarDate.getSolar().solarYear; int month = calendarDate.getSolar().solarMonth; int day = calendarDate.getSolar().solarDay; if (isChoiceModelSingle) {  tv_date.setText(year + "-" + month + "-" + day); } else {  //System.out.println(calendarDate.getSolar().solarDay);  mListDate.add(calendarDate);  tv_date.setText(listToString(mListDate)); }  }  @Override public void OnDateCancel(CalendarDate calendarDate) { int count = mListDate.size(); for (int i = 0; i < count; i++) {  CalendarDate date = mListDate.get(i);  if (date.getSolar().solarDay == calendarDate.getSolar().solarDay) {  mListDate.remove(i);  break;  } } tv_date.setText(listToString(mListDate)); }  @Override public void OnPageChange(int year, int month) { tv_date.setText(year + "-" + month); mListDate.clear(); }  private static String listToString(List<CalendarDate> list) { StringBuffer stringBuffer = new StringBuffer(); for (CalendarDate date : list) {  stringBuffer.append(date.getSolar().solarYear + "-" + date.getSolar().solarMonth + "-" + date.getSolar().solarDay).append(" "); } return stringBuffer.toString(); } }

 if (isChoiceModelSingle) {  mGridView.setChoiceMode(GridView.CHOICE_MODE_SINGLE); } else {  mGridView.setChoiceMode(GridView.CHOICE_MODE_MULTIPLE); } mGridView.setOnItemClickListener(new AdapterView.OnItemClickListener() {  @Override  public void onItemClick(AdapterView<?> parent, View view, int position, long id) {  CalendarDate calendarDate = ((CalendarGridViewAdapter) mGridView.getAdapter()).getListData().get(position);  if (isChoiceModelSingle) {   //單選   if (finalMListDataCalendar.get(position).isInThisMonth()) {   onDateClickListener.OnDateClick(calendarDate);   } else {   mGridView.setItemChecked(position, false);   }  } else {   //多選   if (finalMListDataCalendar.get(position).isInThisMonth()) {   // mGridView.getCheckedItemIds()   if(!mGridView.isItemChecked(position)){    onDateCancelListener.OnDateCancel(calendarDate);   } else {    onDateClickListener.OnDateClick(calendarDate);   }    } else {   mGridView.setItemChecked(position, false);   }   }  } });