我有一个ListView
包含ViewPager
s 的行。当 aViewPager
滚动到屏幕外时,我想保存它的页面位置。当用户ViewPager
再次滚动时,我想恢复其最后保存的页面位置。
我正在尝试使用以下代码来完成此操作:
public class MyBaseAdapter extends BaseAdapter {
// Row ids that will come from server-side, uniquely identifies each
// ViewPager
private List<String> mIds = new ArrayList<String>();
private Map<String, Integer> mPagerPositions = new HashMap<String, Integer>();
@Override
public View getView(int position, View convertView, ViewGroup parent) {
String id = mIds.get(position);
View rootView = convertView;
if (rootView == null) {
rootView = LayoutInflater.from(parent.getContext()).inflate(
R.layout.row, null);
}
ViewPager viewPager = (ViewPager) rootView.findViewById(R.id.pager);
Integer pagerPosition = mPagerPositions.get(id);
if (pagerPosition != null) {
viewPager.setCurrentItem(pagerPosition);
}
viewPager.setOnPageChangeListener(new MyPageChangeListener(id));
return rootView;
}
@Override
public int getCount() {
return mIds.size();
}
@Override
public Object getItem(int position) {
return null;
}
@Override
public long getItemId(int position) {
return 0;
}
private class MyPageChangeListener extends
ViewPager.SimpleOnPageChangeListener {
private String mId;
public MyPageChangeListener(String id) {
mId = id;
}
@Override
public void onPageSelected(int position) {
mPagerPositions.put(mId, position);
}
}
}
页面位置在第一次调用时保存setPagerPosition()
。之后,当ViewPager
离开屏幕时,onPageSelected()
使用保存的第一页位置调用 - 覆盖在仍然可见onPageSelected()
时发生的任何先前调用。ViewPager
这样做的正确方法是什么?