RecyclerView问题加载了n个以上的项目

Question

I've implementend a RecyclerView as follow

The Adapter with the Holder

public class MyAdapter extends RecyclerView.Adapter<MyAdapter.MyHolder> {

    @NonNull
    @Override
    public MyHolder onCreateViewHolder(@NonNull ViewGroup parent, int viewType) {
        View view = LayoutInflater.from(parent.getContext())
                .inflate(R.layout.indovinelloelement,parent,false);

        MyHolder holder = new MyHolder(view);
        return holder;
    }


    @Override
    public void onBindViewHolder(@NonNull MyHolder holder, int position) {
        holder.category.setText(data.get(position).getCategory());
        holder.difficulty.setText(""+data.get(position).getDifficulty());
        holder.title.setText(data.get(position).getTitle());
        holder.score.setText(""+data.get(position).getScore());
        if(data.get(position).isLocked())
            holder.setLocked();
        else
            holder.setUnlocked();

    }


    public DataGestour.Indovinello getIndovinello(int pos){
        return data.get(pos);
    }


    @Override
    public int getItemCount() {
        return data.size();
    }


    public class MyHolder extends RecyclerView.ViewHolder {

        public TextView category,score,difficulty,title;

        private ImageView lock_state;

        public MyHolder(View itemView) {
            super(itemView);
            category = (TextView)itemView.findViewById(R.id.categoria);
            score = (TextView)itemView.findViewById(R.id.punteggio);
            difficulty = (TextView) itemView.findViewById(R.id.difficolta);
            title = (TextView)itemView.findViewById(R.id.titolo);

            lock_state = (ImageView) itemView.findViewById(R.id.lock_state);
        }

        public void setLocked(){
            lock_state.setImageResource(R.drawable.ic_lock_outline_black_24dp);
        }

        public void setUnlocked(){
            lock_state.setImageResource(R.drawable.ic_lock_open_black_24dp);
        }
    }



    ArrayList<DataGestour.Indovinello> data;
    Context context;
    public MyAdapter(Context context, ArrayList<DataGestour.Indovinello> list){
        this.context = context;
        this.data = list;
    }
}

and the RecyclerView:

rc = (RecyclerView)root_view.findViewById(R.id.lista_domande);
    rc.setHasFixedSize(true);

LinearLayoutManager ly = new LinearLayoutManager(getContext());
ly.setOrientation(LinearLayoutManager.VERTICAL);

rc.setLayoutManager(ly);

try{
    gestour = new DataGestour(getContext());
}catch (IllegalStateException e){
    Log.e("DataManager",e.getMessage());
};

adapter = new MyAdapter(getContext(),gestour.getAllDatas());

rc.setAdapter(adapter);
adapter.notifyDataSetChanged();

where DataGestoure is a class that manipulates some data from a database and store them in a ArrayList (DataGestour.getAllDatas is the method to return the data under a ArrayList)

The problem start only if the ArrayList contains more then 3 items becouse the RecyclerView doen't show them despite the fact that the adapter holds all the data in ArrayList< DataGestour.Indovinello > data

Answer 1

Well, you need a little more order in your code, since it is not properly structured, by default the RecyclerView has its Scrolleable view unless in the XML this attribute is removed, well I recommend that you use this code in your adapter and use a model to save the information you get from your BD, that is the correct way to work to keep everything in order and it is easier to work it, once this is done you can use this code perfectly that I am sure will work, remember to only pass information to my Model that in my case calls it "Model" and with this the error of your data load will be solved. It is also advisable to use a List <> for these cases since the Arrays <> tend to have errors when you manipulate the data and more if you do it the way you present the code.

private List<Model> mDataList;

public MyAdapter(Context context){
        this.context = context;
        this.mDataList = new ArrayList<>();
    }

public class MyAdapter extends RecyclerView.Adapter<MyAdapter.MyHolder> {

@NonNull
@Override
public MyHolder onCreateViewHolder(@NonNull ViewGroup parent, int viewType) {
    View view = LayoutInflater.from(parent.getContext())
            .inflate(R.layout.indovinelloelement,parent,false);

    return new MyHolder(view);
}


@Override
public void onBindViewHolder(@NonNull MyHolder holder, int position) {
    MyHolder holder = (MyHolder) MyHolder;
    hoder.bind(mDataList.getPosition(position));
}

@Override
public int getItemCount() {
    return mDataList.size();
}

 public void setData(List<Model> list) {
    mDataList.clear();
    mDataList.addAll(list);
    notifyDataSetChanged();
}


public class MyHolder extends RecyclerView.ViewHolder {

    TextView category;
    category = (TextView)itemView.findViewById(R.id.categoria);
    TextView score;
    score = (TextView)itemView.findViewById(R.id.punteggio);
    TextView difficulty;
    difficulty = (TextView) itemView.findViewById(R.id.difficolta);
    TextView title;
    title = (TextView)itemView.findViewById(R.id.titolo);
    ImageView lock_state;
    lock_state = (ImageView) itemView.findViewById(R.id.lock_state);

    public MyHolder(View itemView) {
        super(itemView);
    }

    protected void bind(Model model){
        category.setText(model.getCategory());
        score.setText(model.getScore());
        difficulty.setText(model.getDifficulty());
        title.setText(model.getTitle());

        if(model.isLocked()){
            lock_state.setImageResource(R.drawable.ic_lock_outline_black_24dp);
        } else {
            lock_state.setImageResource(R.drawable.ic_lock_open_black_24dp);
        }
    }
}
}

And for your class that contains the RecyclerView use the code as follows.

RecyclerView mRecyclerView;
mRecyclerView = (RecyclerView)root_view.findViewById(R.id.lista_domande);

private MyAdapter mAdapter;
private List<Model> mDataList;
private DataGestour gestour;

private void setupRecyclerView(){

LinearLayoutManager linearLayoutManager = new LinearLayoutManager(getContext());
linearLayoutManager.setOrientation(LinearLayoutManager.VERTICAL);

mRecyclerView.setHasFixedSize(true);
mRecyclerView.setLayoutManager(linearLayoutManager);

mAdapter = new MyAdapter(getContext());
mRecyclerView.setAdapter(mAdapter);
mRecyclerView.setData(mDataList);

}

private void getDataDB(){
    mDataList.add(gestour.getAllDatas);
}