我正在使用Recycler View来加载片段上的项目列表。可以使用application/octet-stream替换此片段。
当我更改片段，然后返回到此片段时，将按预期维护Recycler View卷轴;这是Bottom Bar Navigation方法的代码：
onCreteView()这里，重要的部分是@Override
public View onCreateView(LayoutInflater inflater, final ViewGroup container,
Bundle savedInstanceState) {
// Inflate the layout for this fragment
View cl = inflater.inflate(R.layout.fragment_contents, container, false);
contentList = (RecyclerView) cl.findViewById(R.id.contentList);
RecyclerView.LayoutManager mLayoutManager = new LinearLayoutManager(getActivity().getApplicationContext());
contentList.setLayoutManager(mLayoutManager);
contentList.setItemAnimator(new DefaultItemAnimator());
contentList.addItemDecoration(new DividerItemDecoration(getActivity().getApplicationContext(), LinearLayoutManager.VERTICAL));
SharedPreferences sharedPref = getActivity().getSharedPreferences(MainActivity.PACKAGE_NAME, Context.MODE_PRIVATE);
boolean contentsLoaded = sharedPref.getBoolean("contentsLoaded", false);
swipeRefreshLayout = (SwipeRefreshLayout) cl.findViewById(R.id.contents_swipe);
swipeRefreshLayout.setOnRefreshListener(new SwipeRefreshLayout.OnRefreshListener() {
@Override
public void onRefresh() {
content_list.getContents().clear();
loadContents(getActivity().getApplicationContext());
}
});
contentList.addOnItemTouchListener(
new ChannelRecyclerItemClickListener(getActivity().getApplicationContext(), contentList ,new ChannelRecyclerItemClickListener.OnItemClickListener() {
@Override public void onItemClick(View view, int position) {
Intent contentActivity = new Intent(getActivity().getApplicationContext(), ContentActivity.class );
Content content = (Content) view.getTag();
Channel channel = content_list.findChannelById(content.getChannelId());
Town town = content_list.findTownById(content.getTownId());
User author = content_list.findUserById(content.getAuthorId());
contentActivity.putExtra("id", content.getId());
contentActivity.putExtra("title", content.getTitle());
contentActivity.putExtra("lastEdit", new SimpleDateFormat("dd/MM/yy").format(content.getLastEdit()));
contentActivity.putExtra("description", content.getDescription());
contentActivity.putExtra("channelName", channel.getName());
contentActivity.putExtra("channelPic", channel.getPicture());
contentActivity.putExtra("townName", town.getName());
contentActivity.putExtra("townPic", town.getPicture());
contentActivity.putExtra("authorName", author.getName());
contentActivity.putExtra("authorSurname", author.getSurname());
startActivity(contentActivity);
}
@Override public void onLongItemClick(View view, int position) {
// do whatever
}
})
);
if(contentsLoaded) {
LoadFromCache();
return cl;
}
loadContents(getActivity().getApplicationContext());
SharedPreferences.Editor editor = sharedPref.edit();
editor.putBoolean("contentsLoaded", true);
editor.apply();
return cl;
}
调用，它从数据库中检索项目并重新加载RecyclerView。
当我将此代码放在我的LoadFromCache()方法上时出现问题：
onResume()然后，当我在片段之间切换时，滚动被重置为顶部。我无法理解为什么 @Override
public void onResume() {
super.onResume();
LoadFromCache();
}
方法工作正常，而不是我的onCreateView()方法，因为它是同一个调用。
更多信息：
LoadFromCache（）函数：
onResume()LoadContentsFromDatabase类：
public void LoadFromCache(Void...voids){
new LoadContentsFromDatabase(contentList).execute();
}
编辑：我如何在片段之间切换
我的家庭活动负责管理片段切换：
public class LoadContentsFromDatabase extends AsyncTask<Void, Void, ContentList> {
@SuppressLint("StaticFieldLeak")
RecyclerView contentList;
public LoadContentsFromDatabase(RecyclerView contentList) {
this.contentList = contentList;
}
@Override
protected void onPreExecute() {
super.onPreExecute();
//Perform pre-adding operation here.
}
@Override
protected ContentList doInBackground(Void...voids) {
//Select data from DB
List<Town> towns = db.townDao().getAll();
List<Channel> channels = db.channelDao().getAll();
List<User> users = db.userDao().getAll();
List<Content> contents = db.contentDao().getAll();
return new ContentList(new ArrayList(contents), new ArrayList(towns), new ArrayList(channels), new ArrayList(users), null);
}
@Override
protected void onPostExecute(ContentList list) {
super.onPostExecute(list);
//To after addition operation here.
contentAdapter = new ContentAdapter(list);
contentList.setItemAnimator(new DefaultItemAnimator());
contentList.setAdapter(contentAdapter);
contentAdapter.notifyDataSetChanged();
ContentsFragment.content_list = list;
}
}