Question

我有一个包含RecyclerView的PopupWindow。 RecyclerView的最后一个元素是一个按钮，在单击时将新项添加到适配器列表的末尾。

问题：在我的PopupWindow第一次启动时，按钮在单击时成功将新项目添加到RecyclerView并notifyItemInserted(dataSize - 1)，但RecyclerView不会更新并显示它们。但是，如果我关闭并重新打开PopupWindow，之前添加的项目会在RecyclerView 和中正确显示，它会正确更新并动画添加到其适配器的新项目。

问题：我不确定为什么RecyclerView在第一次运行PopupWindow时不刷新并显示新添加的项目，但从第二次运行开始就完美运行。如何在第一次运行PopupWindow时使其工作？

P.S。值得注意的是，如果我使用notifyDataSetChanged()，即使首次启动PopupWindow，RecyclerView也能正常工作（显示新项目）。我想找到一种让notifyItemInserted()工作的方法，因为它在添加新项目时有很好的动画效果。

UserChordsAdapter.java

public class UserChordsAdapter extends RecyclerView.Adapter<UserChordsAdapter.ChordViewHolder> {

private Context context;
private final ListItemClickListener mClickHandler;
private ArrayList<String> mChordData = new ArrayList<String>();    //contains all user created chords as comma delimited note #s

/**
 * The interface that receives onClick messages.
 */
public interface ListItemClickListener {
    void onListItemClick(int clickedItemIndex);
}

/**
 *
 * @param clickHandler The on-click handler for this adapter. This single handler is called
 *                     when an item is clicked.
 */
public UserChordsAdapter(ListItemClickListener clickHandler) {
    mClickHandler = clickHandler;
}

@Override
public ChordViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
    context = parent.getContext();
    int layoutIdForListItem = R.layout.user_chord_list_item;
    int layoutIdForFooterItem = R.layout.user_chord_add_new;
    LayoutInflater inflater = LayoutInflater.from(context);
    boolean shouldAttachToParentImmediately = false;

    View listItem;
    ChordViewHolder viewHolder;

    if (viewType == R.layout.user_chord_list_item) {    //inflate chord item
        listItem = inflater.inflate(layoutIdForListItem, parent, shouldAttachToParentImmediately);
        viewHolder = new ChordViewHolder(listItem);
    }
    else {                                               //inflate "+ Add new" button (last list item)
        listItem = inflater.inflate(layoutIdForFooterItem, parent, shouldAttachToParentImmediately);
        viewHolder = new ChordViewHolder(listItem);
    }

    return viewHolder;
}

@Override
public void onBindViewHolder(ChordViewHolder holder, int position) {
    if (position == mChordData.size()){
        holder.mAddChordButton.setOnClickListener(new View.OnClickListener(){
            @Override
            public void onClick(View v) {
                mChordData.add("1,30,40");
                notifyItemInserted(mChordData.size()-1);
            }
        });
    }
    else {
        holder.mChordName.setText("Chord " + Integer.toString(position));
    }
}

@Override
public int getItemCount() {
    if (mChordData == null){
        return 1;
    }
    return mChordData.size() + 1; // +1 is for footer button (add new)
}

class ChordViewHolder extends RecyclerView.ViewHolder implements View.OnClickListener {

    // Will display which ViewHolder is displaying this data
    TextView mChordName;
    Button mAddChordButton;

    /**
     * Constructor for our ViewHolder. Within this constructor, we get a reference to our
     * TextViews and set an onClickListener to listen for clicks. Those will be handled in the
     * onClick method below.
     */
    public ChordViewHolder(View itemView) {
        super(itemView);

        mAddChordButton = (Button) itemView.findViewById(R.id.button_add_new);
        mChordName = (TextView) itemView.findViewById(R.id.tv_view_holder_instance);
        itemView.setOnClickListener(this);
    }

    /**
     * Called whenever a user clicks on an item in the list.
     * @param v The View that was clicked
     */
    @Override
    public void onClick(View v) {
        int clickedPosition = getAdapterPosition();
        String chordData = mChordData.get(clickedPosition);
        mClickHandler.onListItemClick(clickedPosition);
    }
}

/**
 * Distinguishes if view is a Chord list item or the last item in the list (add new chord)
 * @param position
 * @return
 */
@Override
public int getItemViewType(int position) {
    return (position == mChordData.size()) ? R.layout.user_chord_add_new : R.layout.user_chord_list_item;
}}

FragmentChordMenu.java

public class FragmentChordMenu extends Fragment implements UserChordsAdapter.ListItemClickListener{
private FloatingActionButton mFAB;
private View mPopupView;
private PopupWindow mUserChordMenu;
private RecyclerView mUserChordsList;
private UserChordsAdapter mRecyclerViewAdapter;
private int numItems = 0;   //TODO: dynamically calculate this as # of saved chords + 1(add new)

@Override
public void onActivityCreated(@Nullable Bundle savedInstanceState) {
    super.onActivityCreated(savedInstanceState);
    mRecyclerViewAdapter = new UserChordsAdapter(this);
}

@Nullable
@Override
public View onCreateView(LayoutInflater inflater, @Nullable ViewGroup container, Bundle savedInstanceState) {
    View v = inflater.inflate(R.layout.menu_fragment_chord, container, false);

    LayoutInflater layoutInflater = (LayoutInflater)getActivity().getBaseContext().getSystemService(Context.LAYOUT_INFLATER_SERVICE);
    mPopupView = layoutInflater.inflate(R.layout.menu_popup_set_chords, null);
    int menuWidth = (int)(MainActivity.getActualWidth()*.95);
    int menuHeight = (int)(MainActivity.getActualHeight()*.90);
    mUserChordMenu = new PopupWindow(mPopupView, menuWidth, menuHeight);
    mUserChordMenu.setFocusable(true);

    mFAB = (FloatingActionButton) v.findViewById(R.id.addChord);
    mFAB.setOnClickListener(new View.OnClickListener() {
        public void onClick(View v) {
            mUserChordMenu.showAtLocation(mPopupView, Gravity.CENTER, 10, 10);
            mUserChordsList = (RecyclerView) mPopupView.findViewById(R.id.rv_userChords);
            LinearLayoutManager layoutManager = new LinearLayoutManager(getActivity());
            mUserChordsList.setLayoutManager(layoutManager);
            mUserChordsList.setAdapter(mRecyclerViewAdapter);
        }
    });
    return v;
}


/**
* Called from UserChordsAdapter's onClick. Only fires on list item clicks, not the add new button
 *
* */
@Override
public void onListItemClick(int clickedItemIndex) {
}}

Answer 1

问题在于您用于更新视图的逻辑。目前你所说的是这个，只在屏幕上绘制视图时通知我的数据（OnBind）。这就是为什么它总是适用于第二次尝试，因为无论何时绘制视图（滑动等）。将触发onBind方法。您需要做的是在Adapter类中创建一个替换此逻辑的方法。

   holder.mAddChordButton.setOnClickListener(new View.OnClickListener(){
            @Override
            public void onClick(View v) {
                mChordData.add("1,30,40");
                notifyItemInserted(mChordData.size()-1);
            }
        });

因此，创建一个方法，将项添加到mChorData集对象，然后在该方法中调用notifyItemInserted(mChordData.size()-1);。这将始终更新并通知适配器任何更改，从而自动触发重绘。

首先在UserChordsAdapter中创建一个公共方法，为其参数接受mChordData，然后在该方法调用中notifyItemInserted(mChordData.size()-1);。首先，您需要在该适配器之外公开clickListener。

添加了notifyItemInserted的RecyclerView项目仅在重新加载View后显示

1 个答案: