我的答案是Firebase和位置0是一个变通办法

Parcelable state;

DatabaseReference everybody = db.getReference("Everybody Room List");
    everybody.addValueEventListener(new ValueEventListener() {
        @Override
        public void onDataChange(@NonNull DataSnapshot dataSnapshot) {
            state = listView.onSaveInstanceState(); // Save
            progressBar.setVisibility(View.GONE);
            arrayList.clear();
            for (DataSnapshot messageSnapshot : dataSnapshot.getChildren()) {
                Messages messagesSpacecraft = messageSnapshot.getValue(Messages.class);
                arrayList.add(messagesSpacecraft);
            }
            listView.setAdapter(convertView);
            listView.onRestoreInstanceState(state); // Restore
        }

        @Override
        public void onCancelled(@NonNull DatabaseError databaseError) {
        }
    });

和convertView

位置0 a添加一个您不使用的空白项

public class Chat_ConvertView_List_Room extends BaseAdapter {

private ArrayList<Messages> spacecrafts;
private Context context;

@SuppressLint("CommitPrefEdits")
Chat_ConvertView_List_Room(Context context, ArrayList<Messages> spacecrafts) {
    this.context = context;
    this.spacecrafts = spacecrafts;
}

@Override
public int getCount() {
    return spacecrafts.size();
}

@Override
public Object getItem(int position) {
    return spacecrafts.get(position);
}

@Override
public long getItemId(int position) {
    return position;
}

@SuppressLint({"SetTextI18n", "SimpleDateFormat"})
@Override
public View getView(final int position, View convertView, ViewGroup parent) {
    if (convertView == null) {
        convertView = LayoutInflater.from(context).inflate(R.layout.message_model_list_room, parent, false);
    }

    final Messages s = (Messages) this.getItem(position);

    if (position == 0) {
        convertView.getLayoutParams().height = 1; // 0 does not work
    } else {
        convertView.getLayoutParams().height = RelativeLayout.LayoutParams.WRAP_CONTENT;
    }

    return convertView;
}
}

我已经看到这个工作暂时不打扰用户，我希望它为您工作

用于从实现LoaderManager的ListActivity派生的活动。LoaderCallbacks使用SimpleCursorAdapter，它不能恢复onReset()中的位置，因为活动几乎总是重新启动，并且当详细信息视图关闭时适配器被重新加载。诀窍是恢复onLoadFinished()中的位置:

在onListItemClick ():

// save the selected item position when an item was clicked
// to open the details
index = getListView().getFirstVisiblePosition();
View v = getListView().getChildAt(0);
top = (v == null) ? 0 : (v.getTop() - getListView().getPaddingTop());

在onLoadFinished ():

// restore the selected item which was saved on item click
// when details are closed and list is shown again
getListView().setSelectionFromTop(index, top);

在onBackPressed ():

// Show the top item at next start of the app
index = 0;
top = 0;

这里提供的解决方案似乎都不适合我。在我的情况下，我有一个ListView在一个片段，我替换在一个FragmentTransaction，所以一个新的片段实例创建每次片段显示，这意味着ListView状态不能存储为片段的成员。

相反，我最终将状态存储在我的自定义Application类中。下面的代码应该会让你了解它是如何工作的:

public class MyApplication extends Application {
    public static HashMap<String, Parcelable> parcelableCache = new HashMap<>();


    /* ... code omitted for brevity ... */
}

public class MyFragment extends Fragment{
    private ListView mListView = null;
    private MyAdapter mAdapter = null;


    @Override
    public void onViewCreated(View view, @Nullable Bundle savedInstanceState) {
        super.onViewCreated(view, savedInstanceState);

        mAdapter = new MyAdapter(getActivity(), null, 0);
        mListView = ((ListView) view.findViewById(R.id.myListView));

        Parcelable listViewState = MyApplication.parcelableCache.get("my_listview_state");
        if( listViewState != null )
            mListView.onRestoreInstanceState(listViewState);
    }


    @Override
    public void onPause() {
        MyApplication.parcelableCache.put("my_listview_state", mListView.onSaveInstanceState());
        super.onPause();
    }

    /* ... code omitted for brevity ... */

}

基本思想是将状态存储在片段实例之外。如果您不喜欢在应用程序类中拥有静态字段的想法，我猜您可以通过实现一个片段接口并将状态存储在您的活动中来实现它。

另一种解决方案是将其存储在SharedPreferences中，但这有点复杂，您需要确保在应用程序启动时清除它，除非您希望在应用程序启动时保持状态。

另外，为了避免“当第一项可见时滚动位置不保存”，你可以显示一个0px高度的虚拟第一项。这可以通过重写适配器中的getView()来实现，如下所示:

@Override
public View getView(int position, View convertView, ViewGroup parent) {
    if( position == 0 ) {
        View zeroHeightView = new View(parent.getContext());
        zeroHeightView.setLayoutParams(new ViewGroup.LayoutParams(0, 0));
        return zeroHeightView;
    }
    else
        return super.getView(position, convertView, parent);
}

如果在重新加载前保存状态，并在重新加载后恢复状态，则可以在重新加载后保持滚动状态。在我的情况下，我做了一个异步网络请求，并在它完成后在回调中重新加载列表。这是我恢复状态的地方。代码示例是Kotlin。

val state = myList.layoutManager.onSaveInstanceState()

getNewThings() { newThings: List<Thing> ->

    myList.adapter.things = newThings
    myList.layoutManager.onRestoreInstanceState(state)
}

最好的解决方案是:

// save index and top position
int index = mList.getFirstVisiblePosition();
View v = mList.getChildAt(0);
int top = (v == null) ? 0 : (v.getTop() - mList.getPaddingTop());

// ...

// restore index and position
mList.post(new Runnable() {
    @Override
    public void run() {
      mList.setSelectionFromTop(index, top);
   }
});

你必须在邮件和线程中调用!

使用下面的代码:

int index,top;

@Override
protected void onPause() {
    super.onPause();
    index = mList.getFirstVisiblePosition();

    View v = challengeList.getChildAt(0);
    top = (v == null) ? 0 : (v.getTop() - mList.getPaddingTop());
}

无论何时你刷新你的数据使用下面的代码:

adapter.notifyDataSetChanged();
mList.setSelectionFromTop(index, top);