我是安卓新手。我为我的应用程序开发了一个日历，我希望用户能够在月份之间顺利切换。所以我决定使用 ViewPager 并让它使用无限的几个月，我已经实施了这个解决方案：
不幸的是，它对我不起作用。当我尝试向左或向右滚动时，下一个要显示的月份到来，直到我用手指滚动，但是当我松开手指时，较早显示的月份又来了，但指示器上的日期仍然是正确的。
我发布代码：
calendarView = new GridView(this);
calendarView.setLayoutParams(new ViewGroup.LayoutParams(
ViewGroup.LayoutParams.WRAP_CONTENT,
ViewGroup.LayoutParams.WRAP_CONTENT));
calendarView.setNumColumns(7);
adapter = new GridCellAdapter(getApplicationContext(), R.id.calendar_day_gridcell, newdatum);
adapter.notifyDataSetChanged();
calendarView.setAdapter(adapter);
calendarView.setTag(newdatum.toString());
viewpager = (ViewPager) this.findViewById(R.id.calviewpager);
viewpager.setAdapter(new MonthPagerAdapter());
viewpager.setOffscreenPageLimit(3);
mTitleIndicator = (TitlePageIndicator) findViewById(R.id.indicator);
mTitleIndicator.setViewPager(viewpager, 1);
mTitleIndicator.setOnPageChangeListener(new PageListener());
}
private class PageListener implements OnPageChangeListener{
@Override
public void onPageScrolled(int position, float positionOffset, int positionOffsetPixels) {
}
@Override
public void onPageScrollStateChanged(int state) {
if (state == ViewPager.SCROLL_STATE_IDLE) {
final DateTime old0 = DateTime.parse(viewpager.getChildAt(0).getTag().toString());
final DateTime old1 = DateTime.parse(viewpager.getChildAt(1).getTag().toString());
final DateTime old2 = DateTime.parse(viewpager.getChildAt(2).getTag().toString());
if (focusedPage == 0) {
Log.d("FOCUSEDPAGE=0",newdatum.toString());
DateTime minus = new DateTime();
minus=old0.minusMonths(1);
viewpager.getChildAt(0).setTag(minus.toString());
viewpager.getChildAt(1).setTag(old2.toString());
viewpager.getChildAt(2).setTag(old1.toString());
}
else if (focusedPage == 2) {
Log.d("FOCUSEDPAGE=2",newdatum.toString());
DateTime plus = new DateTime();
plus=old2.plusMonths(1);
viewpager.getChildAt(0).setTag(old1.toString());
viewpager.getChildAt(1).setTag(old2.toString());
viewpager.getChildAt(2).setTag(plus.toString());
}
mTitleIndicator.setCurrentItem(1);
}
}
@Override
public void onPageSelected(int position) {
newdatum=DateTime.parse(viewpager.getChildAt(position).getTag().toString());
focusedPage = position;
}
}
private class MonthPagerAdapter extends PagerAdapter{
ViewPager container;
private GridView addMonthViewAt(int position, DateTime date) {
final GridView gv = new GridView(CalendarActivity.this);
gv.setLayoutParams(new ViewGroup.LayoutParams(
ViewGroup.LayoutParams.WRAP_CONTENT,
ViewGroup.LayoutParams.WRAP_CONTENT));
gv.setNumColumns(7);
gv.setTag(date.toString());
setGridCellAdapterToDate(date, gv);
container.addView(gv, position);
return gv;
}
@Override
public void destroyItem(View container, int position, Object object) {
((ViewPager) container).removeViewAt(position);
}
@Override
public void finishUpdate(View container) {
}
@Override
public int getCount() {
return 3;
}
@Override
public Object instantiateItem(View container, int pos) {
this.container = (ViewPager) container;
DateTime newdate=newdatum.plusMonths(pos-1);
Log.d("INSTATIATE",newdate.toString());
return addMonthViewAt(pos, newdate);
}
@Override
public String getPageTitle(int position) {
final GridView gv = (GridView) container.getChildAt(position);
DateTime dt=DateTime.parse(gv.getTag().toString());
String title=dt.monthOfYear().getAsText()+" "+dt.getYear();
Log.d("GET PAGE TITLE",dt.toString());
return title;
}
@Override
public boolean isViewFromObject(View view, Object object) {
return view.equals(object);
}
@Override
public void restoreState(Parcelable state, ClassLoader loader) {
}
@Override
public Parcelable saveState() {
return null;
}
@Override
public void startUpdate(View container) {
}
}
private void setGridCellAdapterToDate(DateTime newdate, GridView gridview){
GridCellAdapter adapt = new GridCellAdapter(getApplicationContext(), R.id.calendar_day_gridcell, newdate);
adapt.notifyDataSetChanged();
gridview.setAdapter(adapt);
}
以及 GridCellAdapter 代码：
public class GridCellAdapter extends BaseAdapter implements OnClickListener{
private final Context _context;
private final List<String> list;
private Button gridcell;
public GridCellAdapter(Context context, int textViewResourceId, DateTime datum){
super();
this._context = context;
this.list = new ArrayList<String>();
printMonth(datum);
}
public String getItem(int position){
return list.get(position);
}
public int getCount(){
return list.size();
}
private void printMonth(DateTime cal){
int daysInMonth = cal.dayOfMonth().getMaximumValue();
int daysInPrevMonth = cal.minusMonths(1).dayOfMonth().getMaximumValue()+1;
int trailingSpaces = cal.withDayOfMonth(1).dayOfWeek().get()-1;
SQLiteAdapter sql= new SQLiteAdapter(getApplicationContext());
sql.openToWrite(month(cal));
if(sql.tableExists()){
String back="blue";
for(int i=0;i<7;i++)
list.add("DAY:"+cal.withDayOfWeek(i+1).toString()+": ");
for (int i = 0; i < trailingSpaces; i++){
if(sql.rowExists(cal.minusMonths(1).withDayOfMonth((daysInPrevMonth-trailingSpaces)+i).toString("yyyy-MM-dd")))
back="green";
else back="blue";
list.add("GREY:"+cal.minusMonths(1).withDayOfMonth((daysInPrevMonth-trailingSpaces)+i).toString("yyyy-MM-dd")+": "+":"+back);
}
for (int i = 1; i <= daysInMonth; i++){
if(sql.rowExists(cal.withDayOfMonth(i).toString("yyyy-MM-dd")))
back="green";
else back="blue";
if (cal.withDayOfMonth(i).toString("yyyy-MM-dd").equals(DateTime.now().toString("yyyy-MM-dd"))){
list.add("WHITE:"+cal.withDayOfMonth(i).toString("yyyy-MM-dd")+":"+checkIsFeiertag(cal.withDayOfMonth(i)).toString()+":"+back);
}
else{
checkIsFeiertag(cal.withDayOfMonth(i));
list.add("BLUE:"+cal.withDayOfMonth(i).toString("yyyy-MM-dd")+":"+checkIsFeiertag(cal.withDayOfMonth(i)).toString()+":"+back);
}
}
for (int i = 0; i < list.size() % 7; i++){
if(sql.rowExists(cal.plusMonths(1).withDayOfMonth(i+1).toString("yyyy-MM-dd")))
back="green";
else back="blue";
list.add("GREY:"+cal.plusMonths(1).withDayOfMonth(i+1).toString("yyyy-MM-dd")+": "+":"+back);
}
}
else{
for(int i=0;i<7;i++)
list.add("DAY:"+cal.withDayOfWeek(i+1).toString()+": "+": ");
for (int i = 0; i < trailingSpaces; i++){
list.add("GREY:"+cal.minusMonths(1).withDayOfMonth((daysInPrevMonth-trailingSpaces)+i).toString("yyyy-MM-dd")+": "+": ");
}
for (int i = 1; i <= daysInMonth; i++){
if (cal.withDayOfMonth(i).toString("yyyy-MM-dd").equals(DateTime.now().toString("yyyy-MM-dd"))){
list.add("WHITE:"+cal.withDayOfMonth(i).toString("yyyy-MM-dd")+":"+checkIsFeiertag(cal.withDayOfMonth(i)).toString()+": ");
}
else{
checkIsFeiertag(cal.withDayOfMonth(i));
list.add("BLUE:"+cal.withDayOfMonth(i).toString("yyyy-MM-dd")+":"+checkIsFeiertag(cal.withDayOfMonth(i)).toString()+": ");
}
}
for (int i = 0; i < list.size() % 7; i++){
list.add("GREY:"+cal.plusMonths(1).withDayOfMonth(i+1).toString("yyyy-MM-dd")+": "+": ");
}
}
sql.close();
}
public long getItemId(int position){
return position;
}
@SuppressLint("NewApi")
public View getView(int position, View convertView, ViewGroup parent){
View row = convertView;
if(row == null){
LayoutInflater inflater = (LayoutInflater) _context.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
row = inflater.inflate(R.layout.calendar_day_gridcell, parent, false);
}
gridcell = (Button) row.findViewById(R.id.calendar_day_gridcell);
String[] day_color = list.get(position).split(":");
DateTime datum = DateTime.parse(day_color[1]);
if(!(day_color[0].equals("DAY"))){
gridcell.setText(String.valueOf(datum.getDayOfMonth()));
gridcell.setTag(datum.toString("yyyy-MM-dd"));
gridcell.setOnClickListener(this);
if (!day_color[2].equals(" "))
gridcell.setTextColor(Color.RED);
else if (day_color[0].equals("GREY"))
{
gridcell.setTextColor(Color.LTGRAY);
}
else if (day_color[0].equals("WHITE"))
{
gridcell.setTextColor(Color.WHITE);
}
else if (day_color[0].equals("BLUE"))
{
gridcell.setTextColor(getResources().getColor(R.color.static_text_color));
}
if(day_color[3].equals("green")){
int sdk = android.os.Build.VERSION.SDK_INT;
if(sdk < android.os.Build.VERSION_CODES.JELLY_BEAN) {
gridcell.setBackgroundDrawable(getResources().getDrawable(R.drawable.calendar_tile_green));
} else {
gridcell.setBackground(getResources().getDrawable(R.drawable.calendar_tile_green));
}
}
}
else {
gridcell.setText(datum.toString("EE"));
gridcell.setClickable(false);
}
gridcell.setOnLongClickListener(new View.OnLongClickListener() {
public boolean onLongClick(View v) {
if(gridcell.getBackground()==getResources().getDrawable(R.drawable.calendar_tile_green)){
SQLiteAdapter sql= new SQLiteAdapter(context);
DateTime bt = DateTime.parse(gridcell.getTag().toString());
sql.openToWrite(month(bt));
sql.getRows(month(bt));
sql.close();
}
return true;
}
});
return row;
}
当然，我接受不同的解决方案来提供相同的平滑滚动。