java - Firebase RecyclerView 适配器无法获得准确的 View 位置

Question

我正在使用 Firebase UI，但遇到了一个独特的问题。当我加载 RecyclerView 时，没有任何问题。我单击 RecyclerView 上的一个项目并获取所单击项目的 .push() 值。然后，它从存储在 Firebase 数据库中的 Firebase .push() 值中获取数据，并将其发送到另一个 Activity 。参见下图:

第二张图片是通过 Intent 接收数据的 Activity 。当我点击返回 RecyclerView 时，我再次点击“8”，然后加载一个不同的数字(现在看起来是 1)。

最终，我担心我没有正确设置 RecyclerView。这是我的代码:

创建 Poll 对象 (POJO) 并写入 Firebase:

        mSubmitPollCreation.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {

            //TODO: Need to check if poll requirements are added, i.e. Question, Answer, ......
            //check if image has been loaded first
            if (resultImageURL == null) {
                Toast.makeText(getApplicationContext(), getResources().getString(R.string.no_image_selected), Toast.LENGTH_LONG).show();
                return;
            }

            //capture answers
            if (mNumberOfPollAnswersCreatedByUser > 5) {
                Toast.makeText(getApplicationContext(), getResources().getText(R.string.poll_answers_greater_than_five), Toast.LENGTH_LONG).show();
                mNumberOfPollAnswersCreatedByUser = 5;
            }
            for (int i = 0; i < mNumberOfPollAnswersCreatedByUser; i++) {
                EditText editText = (EditText) mEditTextAnswerLayout.findViewWithTag(getResources().getString(R.string.created_answer_editText_id) + String.valueOf(i + 1));
                String editTextInputForAnswer = String.valueOf(editText.getText());
                mPollAnswers.add(0, editTextInputForAnswer);                 Toast.makeText(getApplicationContext(),editTextInputForAnswer,Toast.LENGTH_SHORT).show();
            }


            Poll poll = new Poll(mCreatePollQuestion.getText().toString(), resultImageURL, mPollAnswers);
            Map<String, Object> pollMap = poll.toMap();
            final String key = mBaseRef.child("Polls").push().getKey();
            Map<String, Object> childUpdates = new HashMap<String, Object>();
            childUpdates.put("/Polls/" + key, pollMap);

            mBaseRef.updateChildren(childUpdates);
            Collections.reverse(mPollAnswers);
            for (int i = 0; i < mPollAnswers.size(); i++) {
                mBaseRef.child("Polls").child(key).child("answers").child(String.valueOf(i + 1)).updateChildren(poll.answerConvert(mPollAnswers, i));
            }

            Intent toHomeActivity = new Intent(CreateActivity.this, HomeActivity.class);
            toHomeActivity.putExtra("viewpager_position", 2);
            startActivity(toHomeActivity);
        }
    });

我从 Firebase 读取并填充 RecyclerView 的位置:

public class LiveFragment extends Fragment {
// TODO: Rename parameter arguments, choose names that match
// the fragment initialization parameters, e.g. ARG_ITEM_NUMBER
private static final String ARG_PARAM1 = "param1";
private static final String ARG_PARAM2 = "param2";

private RecyclerView mRecyclerview;
private DatabaseReference mBaseRef;
private DatabaseReference mPollsRef;
private LinearLayoutManager mLayoutManager;
private FloatingActionButton mFloatingActionAdd;

private FirebaseRecyclerAdapter<Poll, PollHolder> mFireAdapter;

private RecyclerView.ItemAnimator mItemAnimator;


// TODO: Rename and change types of parameters
private String mParam1;
private String mParam2;

private OnFragmentInteractionListener mListener;

public LiveFragment() {
    // Required empty public constructor
}

/**
 * Use this factory method to create a new instance of
 * this fragment using the provided parameters.
 *
 * @param param1 Parameter 1.
 * @param param2 Parameter 2.
 * @return A new instance of fragment LiveFragment.
 */
// TODO: Rename and change types and number of parameters
public static LiveFragment newInstance(String param1, String param2) {
    LiveFragment fragment = new LiveFragment();
    Bundle args = new Bundle();
    args.putString(ARG_PARAM1, param1);
    args.putString(ARG_PARAM2, param2);
    fragment.setArguments(args);
    return fragment;
}

@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    mBaseRef = FirebaseDatabase.getInstance().getReference();
    mPollsRef = mBaseRef.child("Polls");

    if (getArguments() != null) {
        mParam1 = getArguments().getString(ARG_PARAM1);
        mParam2 = getArguments().getString(ARG_PARAM2);

    }
}

@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
                         Bundle savedInstanceState) {
    // Inflate the layout for this fragment
    final View v = inflater.inflate(R.layout.fragment_new, container, false);
    Log.v("TAG", "ON CREATE CALLED FROM NEW");

    mRecyclerview = (RecyclerView) v.findViewById(R.id.list);
    mRecyclerview.setItemAnimator(new SlideInLeftAnimator());


    mLayoutManager = new LinearLayoutManager(getContext());
    mLayoutManager.setOrientation(LinearLayoutManager.VERTICAL);
    mLayoutManager.setReverseLayout(true);
    mLayoutManager.setStackFromEnd(true);

    mFloatingActionAdd = (FloatingActionButton) getActivity().findViewById(R.id.myFAB);
    mFloatingActionAdd.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            Intent I = new Intent(getActivity().getApplicationContext(), CreateActivity.class);
            startActivity(I);
        }
    });


    mRecyclerview.setLayoutManager(mLayoutManager);
    return v;
}

// TODO: Rename method, update argument and hook method into UI event
public void onButtonPressed(Uri uri) {
    if (mListener != null) {
        mListener.onFragmentInteraction(uri);
    }
    scrollToPosition();
}

@Override
public void onStart() {
    super.onStart();

    mFireAdapter = new FirebaseRecyclerAdapter<Poll, PollHolder>(Poll.class, R.layout.latest_item, PollHolder.class, mBaseRef.child("Polls")) {
        @Override
        protected void populateViewHolder(PollHolder viewHolder, final Poll model, final int position) {
            viewHolder.mPollQuestion.setText(model.getQuestion());
            Picasso.with(getActivity().getApplicationContext())
                    .load(model.getImage_URL())
                    .fit()
                    .into(viewHolder.mPollImage);
            viewHolder.mView.setOnClickListener(new View.OnClickListener() {
                @Override
                public void onClick(View view) {
                    Log.v("TAG", model.toString());
                    Log.v("TAG","ONCLICKED");
                    Intent toPoll = new Intent(getActivity(), PollHostActivity.class);
                    toPoll.putExtra("POLL_ID", mFireAdapter.getRef(position).getKey());
                    startActivity(toPoll);

                }
            });
            Log.v("TAG", mFireAdapter.getRef(position).getKey());
            Log.v("TAG", String.valueOf(position));
            Log.v("TAG", model.getQuestion());
            Log.v("TAG", model.getImage_URL());
        }
    };

    mRecyclerview.setAdapter(mFireAdapter);
    scrollToPosition();



}

@Override
public void onStop() {
    super.onStop();
    if (mFireAdapter != null) {
        mFireAdapter.cleanup();
    }
}


@Override
public void onDetach() {
    super.onDetach();
    mListener = null;
}


public static class PollHolder extends RecyclerView.ViewHolder implements View.OnClickListener {

    TextView mPollQuestion;
    ImageView mPollImage;
    View mView;


    public PollHolder(View itemView) {
        super(itemView);

        mPollQuestion = (TextView) itemView.findViewById(R.id.latest_item_question);
        mPollImage = (ImageView) itemView.findViewById(R.id.pollThumbNailImage);
        this.mView = itemView;
        itemView.setOnClickListener(this);

    }

    @Override
    public void onClick(View view) {
        Log.v("TAG", "CLICKED");
    }
}


private void scrollToPosition(){
    mFireAdapter.registerAdapterDataObserver(new RecyclerView.AdapterDataObserver() {
        @Override
        public void onItemRangeInserted(int positionStart, int itemCount) {
            super.onItemRangeInserted(positionStart, itemCount);
            int pollCount = mFireAdapter.getItemCount();
            int lastVisiblePosition = mLayoutManager.findLastCompletelyVisibleItemPosition();

            // If the recycler view is initially being loaded or the user is at the bottom of the list, scroll
            // to the bottom of the list to show the newly added message.
            if (lastVisiblePosition == -1 ||
                    (positionStart >= (pollCount - 1) && lastVisiblePosition == (positionStart - 1))) {
                mRecyclerview.scrollToPosition(positionStart);
            }
        }
    });
   }
}

我的想法:

1. 我在正确的位置调用 mFireAdapter.cleanup() 吗？

2. 单击“8”并看到“1”的问题不会出现在 RecyclerView 的第一次加载中，只有当我从 Activity (第二张图像)导航回 RecyclerView 时才会出现这种情况。

3. 我调用 .setStackFromEnd(true) 和 .setReverseLayout(true) 来反转存储在 FirebaseDatabase 中的数据，这可能会导致此问题。

4. 我在 .populateViewHolder() 方法中设置了 .setOnClickListener()，并使用以下代码将 Intent 中的 .push() 键传递给下一个 Activity :

     toPoll.putExtra("POLL_ID", mFireAdapter.getRef(position).getKey());
   

此方法可能获取不正确的 key 。

最后，Firebase 数据库:

如有任何帮助，我们将不胜感激!

Answer 1

您不应在 populateViewHolder 之外使用 position，因为它的值可能会有所不同。相反，请将您的 viewHolder 最终化并使用 viewHolder.getAdapterPosition() 来替换它。