有没有办法防止跳过 recyclerview 的布局？

Question

基本上该应用程序只是一个简单的待办事项列表，但是当我添加新任务时，它会出现在 Firebase 上，但不会出现在我的应用程序上，从而出现错误 “E/RecyclerView：未连接适配器；跳过布局”。 我尝试按照 stackoverflow 上的答案修复它，但没有一个对我有帮助，可能是我错误地将调整调整到我的代码。我只是在学习，这是我的第一个项目，我正在按照教程进行操作。 无论如何，这是 MainActivity.java：

@Override
    protected void onCreate(Bundle savedInstanceState) {

        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        

        buttonadd.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v){
                Intent a = new Intent(MainActivity.this, AggiungiPiattoAttivity.class);
                startActivity(a);
            }
        });

        //working with data
        ourdoes = findViewById(R.id.ourdoes);
        ourdoes.setLayoutManager(new LinearLayoutManager(this));

        list = new ArrayList<MyDoes>();

        //get data from firebase
        reference = FirebaseDatabase.getInstance(URL).getReference().child("AppLista");
        reference.addValueEventListener(new ValueEventListener() {
            @Override
            public void onDataChange(DataSnapshot dataSnapshot) {
                //set code to retrive data and replace layout
                for (DataSnapshot dataSnapshot1: dataSnapshot.getChildren())
                {
                    MyDoes p = dataSnapshot1.getValue(MyDoes.class);
                    list.add(p);
                }
                doesAdapter = new DoesAdapter(MainActivity.this, list);
                ourdoes.setAdapter(doesAdapter);
                doesAdapter.notifyDataSetChanged();
            }

            @Override
            public void onCancelled(DatabaseError databaseError) {
                //set code to show an error
                Toast.makeText(getApplicationContext(), "No Data", Toast.LENGTH_SHORT).show();
            }
        });

    }

这是我添加新任务的类：

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_aggiungi_piatto_attivity);

    buttonaddnewpiatto.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
        //insert data to database
        reference = FirebaseDatabase.getInstance(URL).getReference().child("BoxDoese").child("Does" + doesNum);
        reference.addValueEventListener(new ValueEventListener() {
            @Override
            public void onDataChange(@NonNull DataSnapshot dataSnapshot) {
                dataSnapshot.getRef().child("titledoes").setValue(addnamenewpiattosetted.getText().toString());
                dataSnapshot.getRef().child("descdoes").setValue(adddescnewpiattosetted.getText().toString());
                dataSnapshot.getRef().child("qualcosaalpostodiunimmagine").setValue(addrecipenewpiattosetted.getText().toString());

                Intent a = new Intent( AggiungiPiattoAttivity.this, MainActivity.class);
                startActivity(a);
            }

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

            }
        });
    }
});

这是我的适配器类：

public class DoesAdapter extends RecyclerView.Adapter<DoesAdapter.MyViewHolder> {

    Context context;
    ArrayList<MyDoes> myDoes;

    public DoesAdapter(){
    }

    public DoesAdapter(Context c, ArrayList<MyDoes> p ){
        context = c;
        myDoes=p;
    }

    @NonNull
    @Override
    public MyViewHolder onCreateViewHolder(@NonNull ViewGroup viewGroup, int i) {
        return new MyViewHolder(LayoutInflater.from(context).inflate(R.layout.item_does, viewGroup, false));
    }

    @Override
    public void onBindViewHolder(@NonNull MyViewHolder myViewHolder, int i) {
        myViewHolder.titledoes.setText(myDoes.get(i).getTitledoes());
        myViewHolder.qualcosaalpostodiunimmagine.setText(myDoes.get(i).getQualcosaalpostodiunimmagine());
        myViewHolder.descdoes.setText(myDoes.get(i).getDescdoes());

    }

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

    class MyViewHolder extends RecyclerView.ViewHolder{

        TextView titledoes, descdoes, qualcosaalpostodiunimmagine;

        public MyViewHolder(@NonNull View itemView) {
            super(itemView);
            titledoes = (TextView) itemView.findViewById(R.id.titledoes);
            qualcosaalpostodiunimmagine = (TextView) itemView.findViewById(R.id.qualcosaalpostodiunimmagine);
            descdoes = (TextView) itemView.findViewById(R.id.descdoes);
        }
    }
}

我还有其他类，但为了不放太多代码，我避免放它们，它们不应该是相关的。

Answer 1

在为RecyclerView 设置LayoutManager 的同时创建一个空适配器：将其保存为类的字段：

recyclerView.setLayoutManager(new LinearLayoutManager(MainActivity.this));
doesAdapter = new DoesAdapter(MainActivity.this, list);
recyclerView.setAdapter(DoesAdapter);

当数据准备就绪时，填充适配器并通知：

public void onDataChange(@NonNull DataSnapshot dataSnapshot) {
   /// origin code here
  for (DataSnapshot dataSnapshot1: dataSnapshot.getChildren())
            {
                MyDoes p = dataSnapshot1.getValue(MyDoes.class);
                list.add(p);
            }
  // reset data in adapter and not re-creating adapter:
  doesAdapter.setItems(list);
  doesAdapter.notifyDataSetChanged();
 // instead of  doesAdapter = new DoesAdapter(MainActivity.this, list);
  recyclerView.setAdapter(DoesAdapter); 
}

来源：https://stackoverflow.com/a/58251986/12596713