java - 我的 RecyclerView 适配器出现错误，填充了 firebase 数据

Question

我的 recyclerView 适配器出现错误，我不知道到底是什么原因造成的。

recyclerView所在fragment的代码:

public class materiaFragment extends Fragment {
private RecyclerView recyclerView;
private ArrayList<String> listaProf, listaDisc, listaNomeM, nomeSalas, passarSala ;
private DatabaseReference reference = FirebaseDatabase.getInstance().getReference("usuarios/");
private DatabaseReference referenceExec = FirebaseDatabase.getInstance().getReference("salas/");
private DatabaseReference referencePegarExec, referenceProf, referenceDisc, referenceProf2;
private adapterMateria adapterMateria;
private String nomeAluno, teste="", prof="", disc="";
private TextView txtDida;

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


@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
                         Bundle savedInstanceState) {
    // Inflate the layout for this fragment
    View view = inflater.inflate(R.layout.fragment_materia, container, false);
    recyclerView = view.findViewById(R.id.recyclerViewM);
    txtDida= view.findViewById(R.id.txtDida);
    final Context context = view.getContext();

    listaNomeM= new ArrayList<>();
    listaDisc= new ArrayList<>();
    listaProf= new ArrayList<>();
    nomeSalas= new ArrayList<>();
    passarSala= new ArrayList<>();

   pegarM();
    adapterMateria = new adapterMateria(listaProf, listaDisc, listaNomeM, context );
    //adapterSalas adapterMateria = new adapterSalas(listaNomeM, context);
    //configurar recycler view
    RecyclerView.LayoutManager layoutManager = new LinearLayoutManager(context);
    recyclerView.setLayoutManager(layoutManager);
    //recyclerView.setHasFixedSize(true);
    recyclerView.addItemDecoration(new DividerItemDecoration(context, LinearLayout.VERTICAL));
    recyclerView.setAdapter(adapterMateria);

    //evento click
    recyclerView.addOnItemTouchListener(
            new RecyclerItemClickListener(context, recyclerView, new RecyclerItemClickListener.OnItemClickListener() {
                @Override
                public void onItemClick(View view, int position) {

                    // Toast.makeText(context, "Item selecionado: " + exercicio.getNomeAtv(),Toast.LENGTH_SHORT).show();
                    Intent intent = new Intent(getActivity(), verMateriaActivity.class);
                    intent.putExtra("nMateria", listaNomeM.get(position));
                    intent.putExtra("nSala", passarSala.get(position));
                    startActivity(intent);
                }

                @Override
                public void onLongItemClick(View view, int position) {

                    //  Toast.makeText(context, "Click longo: "  + exercicio.getNomeAtv(),Toast.LENGTH_SHORT).show();
                    Intent intent = new Intent(getActivity(), verMateriaActivity.class);
                    startActivity(intent);
                }

                @Override
                public void onItemClick(AdapterView<?> parent, View view, int position, long id) {

                }
            })
    );
    return view;}

    /*
@Override
public void onStart() {
    super.onStart();
    listaProf.clear();
    listaDisc.clear();
    listaNomeM.clear();
    nomeSalas.clear();
    passarSala.clear();

}*/



public void pegarM(){


    FirebaseAuth autenticacao = FirebaseAuth.getInstance();
    String emailUsu = autenticacao.getCurrentUser().getEmail();
    reference.orderByChild("email").equalTo(emailUsu).addListenerForSingleValueEvent(new ValueEventListener() {
        @Override
        public void onDataChange(@NonNull DataSnapshot dataSnapshot) {
            for (DataSnapshot datas : dataSnapshot.getChildren()) {
                nomeAluno = datas.child("nome").getValue().toString();
                referenceExec.orderByChild("alunos/"+ nomeAluno+"/codigo").equalTo(nomeAluno).addListenerForSingleValueEvent(new ValueEventListener() {
                    @Override
                    public void onDataChange(@NonNull DataSnapshot dataSnapshot) {
                        if(dataSnapshot.exists()) {
                            for (DataSnapshot datas : dataSnapshot.getChildren()) {
                                nomeSalas.add(datas.getKey());
                            }
                            for (int i = 0; i < nomeSalas.size(); i++) {

                                referencePegarExec = FirebaseDatabase.getInstance().getReference("salas/" + nomeSalas.get(i) + "/materia/");
                                referenceProf = FirebaseDatabase.getInstance().getReference("salas/" + nomeSalas.get(i) + "/nomeProf");


                                final int finalI = i; // o erro eu
                                referencePegarExec.addValueEventListener(new ValueEventListener() {
                                    @Override
                                    public void onDataChange(@NonNull DataSnapshot dataSnapshot) {
                                        for (DataSnapshot dsp : dataSnapshot.getChildren()) {
                                            if (!dsp.getKey().equals("1")) {
                                                listaNomeM.add(dsp.getKey());
                                                passarSala.add(nomeSalas.get(finalI));
                                                referenceProf.addListenerForSingleValueEvent(new ValueEventListener() {
                                                    @Override
                                                    public void onDataChange(@NonNull DataSnapshot dataSnapshot) {
                                                        listaProf.add(dataSnapshot.getValue(String.class));
                                                        referenceDisc = FirebaseDatabase.getInstance().getReference("salas/" + nomeSalas.get(finalI) + "/disciplina");

                                                        referenceDisc.addListenerForSingleValueEvent(new ValueEventListener() {
                                                            @Override
                                                            public void onDataChange(@NonNull DataSnapshot dataa) {
                                                                listaDisc.add(dataa.getValue().toString());
                                                                adapterMateria.notifyDataSetChanged();
                                                                // txtNomeA.setText(dataa.getValue(String.class));

                                                            }

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

                                                            }
                                                        });
                                                    }

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

                                                    }
                                                });

                                            }

                                        }

                                    }

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

                                    }
                                });
                            }
                        }else {
                            txtDida.setText("Nenhum arquivo didático disponível");
                        }


                    }



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

            }
        }

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

}

适配器:

public class adapterMateria extends RecyclerView.Adapter<adapterMateria.myViewHolder> {
private ArrayList<String> listaProf, listaDisc, listaNomeM ;
private Context context;

public adapterMateria(ArrayList<String> listaProf, ArrayList<String> listaDisc, ArrayList<String> listaNomeM, Context context) {
    this.listaProf = listaProf;
    this.listaDisc = listaDisc;
    this.listaNomeM = listaNomeM;
    this.context = context;
}

@NonNull
@Override
public myViewHolder onCreateViewHolder(@NonNull ViewGroup parent, int i) {
    View itemLista = LayoutInflater.from(parent.getContext())
            .inflate(R.layout.adaptermateria_lista, parent, false);

    return new myViewHolder(itemLista);
}

@Override
public void onBindViewHolder(@NonNull myViewHolder holder, int position) {
    holder.nomeMateria.setText(listaNomeM.get(position));
    holder.materiaM.setText(listaDisc.get(position)); //error
    holder.professor.setText(listaProf.get(position));
}

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

public class myViewHolder extends RecyclerView.ViewHolder{
    TextView nomeMateria, materiaM, professor;

    public myViewHolder(@NonNull View itemView) {
        super(itemView);

        nomeMateria= itemView.findViewById(R.id.textNomeConteudo);
        materiaM= itemView.findViewById(R.id.textMateriaM);
        professor= itemView.findViewById(R.id.textProfessor);

    }
}

}

logcat错误消息:

2019-11-11 20:12:32.705 27650-27650/com.example.classmob E/AndroidRuntime: FATAL EXCEPTION: main
Process: com.example.classmob, PID: 27650
java.lang.IndexOutOfBoundsException: Index: 1, Size: 1
    at java.util.ArrayList.get(ArrayList.java:437)
    at com.example.classmob.adapter.adapterMateria.onBindViewHolder(adapterMateria.java:40)
    at com.example.classmob.adapter.adapterMateria.onBindViewHolder(adapterMateria.java:17)
    at android.support.v7.widget.RecyclerView$Adapter.onBindViewHolder(RecyclerView.java:6781)
    at android.support.v7.widget.RecyclerView$Adapter.bindViewHolder(RecyclerView.java:6823)
    at android.support.v7.widget.RecyclerView$Recycler.tryBindViewHolderByDeadline(RecyclerView.java:5752)
    at android.support.v7.widget.RecyclerView$Recycler.tryGetViewHolderForPositionByDeadline(RecyclerView.java:6019)
    at android.support.v7.widget.RecyclerView$Recycler.getViewForPosition(RecyclerView.java:5858)
    at android.support.v7.widget.RecyclerView$Recycler.getViewForPosition(RecyclerView.java:5854)
    at android.support.v7.widget.LinearLayoutManager$LayoutState.next(LinearLayoutManager.java:2230)
    at android.support.v7.widget.LinearLayoutManager.layoutChunk(LinearLayoutManager.java:1557)
    at android.support.v7.widget.LinearLayoutManager.fill(LinearLayoutManager.java:1517)
    at android.support.v7.widget.LinearLayoutManager.onLayoutChildren(LinearLayoutManager.java:612)
    at android.support.v7.widget.RecyclerView.dispatchLayoutStep2(RecyclerView.java:3924)
    at android.support.v7.widget.RecyclerView.dispatchLayout(RecyclerView.java:3641)
    at android.support.v7.widget.RecyclerView.onLayout(RecyclerView.java:4194)
    at android.view.View.layout(View.java:20680)
    at android.view.ViewGroup.layout(ViewGroup.java:6197)
    at android.widget.LinearLayout.setChildFrame(LinearLayout.java:1812)
    at android.widget.LinearLayout.layoutVertical(LinearLayout.java:1656)
    at android.widget.LinearLayout.onLayout(LinearLayout.java:1565)
    at android.view.View.layout(View.java:20680)
    at android.view.ViewGroup.layout(ViewGroup.java:6197)
    at android.support.v4.view.ViewPager.onLayout(ViewPager.java:1775)
    at android.view.View.layout(View.java:20680)
    at android.view.ViewGroup.layout(ViewGroup.java:6197)
    at android.widget.LinearLayout.setChildFrame(LinearLayout.java:1812)
    at android.widget.LinearLayout.layoutVertical(LinearLayout.java:1656)
    at android.widget.LinearLayout.onLayout(LinearLayout.java:1565)
    at android.view.View.layout(View.java:20680)
    at android.view.ViewGroup.layout(ViewGroup.java:6197)
    at android.widget.FrameLayout.layoutChildren(FrameLayout.java:323)
    at android.widget.FrameLayout.onLayout(FrameLayout.java:261)
    at android.view.View.layout(View.java:20680)
    at android.view.ViewGroup.layout(ViewGroup.java:6197)
    at android.widget.LinearLayout.setChildFrame(LinearLayout.java:1812)
    at android.widget.LinearLayout.layoutHorizontal(LinearLayout.java:1801)
    at android.widget.LinearLayout.onLayout(LinearLayout.java:1567)
    at android.view.View.layout(View.java:20680)
    at android.view.ViewGroup.layout(ViewGroup.java:6197)
    at android.support.design.widget.HeaderScrollingViewBehavior.layoutChild(HeaderScrollingViewBehavior.java:142)
    at android.support.design.widget.ViewOffsetBehavior.onLayoutChild(ViewOffsetBehavior.java:41)
    at android.support.design.widget.AppBarLayout$ScrollingViewBehavior.onLayoutChild(AppBarLayout.java:1556)
    at android.support.design.widget.CoordinatorLayout.onLayout(CoordinatorLayout.java:888)
    at android.view.View.layout(View.java:20680)
    at android.view.ViewGroup.layout(ViewGroup.java:6197)
    at android.support.v4.widget.DrawerLayout.onLayout(DrawerLayout.java:1231)
    at android.view.View.layout(View.java:20680)
    at android.view.ViewGroup.layout(ViewGroup.java:6197)
    at android.widget.FrameLayout.layoutChildren(FrameLayout.java:323)
    at android.widget.FrameLayout.onLayout(FrameLayout.java:261)
    at android.view.View.layout(View.java:20680)
    at android.view.ViewGroup.layout(ViewGroup.java:6197)
    at android.widget.LinearLayout.setChildFrame(LinearLayout.java:1812)
`2019-11-11 20:12:32.707 27650-27650/com.example.classmob E/AndroidRuntime:     at android.widget.LinearLayout.layoutVertical(LinearLayout.java:1656)
    at android.widget.LinearLayout.onLayout(LinearLayout.java:1565)
    at android.view.View.layout(View.java:20680)
    at android.view.ViewGroup.layout(ViewGroup.java:6197)
    at android.widget.FrameLayout.layoutChildren(FrameLayout.java:323)
    at android.widget.FrameLayout.onLayout(FrameLayout.java:261)
    at android.view.View.layout(View.java:20680)
    at android.view.ViewGroup.layout(ViewGroup.java:6197)
    at android.widget.LinearLayout.setChildFrame(LinearLayout.java:1812)
    at android.widget.LinearLayout.layoutVertical(LinearLayout.java:1656)
    at android.widget.LinearLayout.onLayout(LinearLayout.java:1565)
    at android.view.View.layout(View.java:20680)
    at android.view.ViewGroup.layout(ViewGroup.java:6197)
    at android.widget.FrameLayout.layoutChildren(FrameLayout.java:323)
    at android.widget.FrameLayout.onLayout(FrameLayout.java:261)
    at com.android.internal.policy.DecorView.onLayout(DecorView.java:792)
    at android.view.View.layout(View.java:20680)
    at android.view.ViewGroup.layout(ViewGroup.java:6197)
    at android.view.ViewRootImpl.performLayout(ViewRootImpl.java:2831)
    at android.view.ViewRootImpl.performTraversals(ViewRootImpl.java:2358)
    at android.view.ViewRootImpl.doTraversal(ViewRootImpl.java:1494)
    at android.view.ViewRootImpl$TraversalRunnable.run(ViewRootImpl.java:7288)
    at android.view.Choreographer$CallbackRecord.run(Choreographer.java:949)
    at android.view.Choreographer.doCallbacks(Choreographer.java:761)
    at android.view.Choreographer.doFrame(Choreographer.java:696)
    at android.view.Choreographer$FrameDisplayEventReceiver.run(Choreographer.java:935)
    at android.os.Handler.handleCallback(Handler.java:873)
    at android.os.Handler.dispatchMessage(Handler.java:99)
    at android.os.Looper.loop(Looper.java:193)
    at android.app.ActivityThread.main(ActivityThread.java:6923)
    at java.lang.reflect.Method.invoke(Native Method)
    at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:493)
    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:870)

我知道导致该错误的原因是适配器的这一行:“holder.materiaM.setText(listaDisc.get(position));”。但是 arrayList、listaDisc 正在正常地从 fragment 获取数据，所以我不知道是什么导致了这个错误。有人可以帮忙吗？

Answer 1

该错误是因为列表大小更改 getItemCount() 可以提供帮助

    @Override
        public int getItemCount() {
    int listSize;

    listSize = listaProf.size()

    if(listSize < listaNomeM.size())
    listSize = listaNomeM.size()

    if(listSize < listaDisc .size())
       listSize = listaDisc.size()

            return listSize;
        }

或者如果您不想丢失元素(但数据)

    @Override
    public void onBindViewHolder(@NonNull myViewHolder holder, int position) {
        holder.nomeMateria.setText(listaNomeM.get(position));

if(position < listaDisc.size() )
        holder.materiaM.setText(listaDisc.get(position));

if(position < listaProf.size() )
        holder.professor.setText(listaProf.get(position));
    }

最后一件事，检查你的方法来填充listaDisc