Firebase RecyclerView 未显示任何数据 [关闭]

Question

我的 firebase 回收器视图数据未显示我已尝试多种方式但找不到我的答案请帮助 我的 Firebase 回收器视图数据未显示我已尝试多种方式但找不到我的答案请帮助 我的 Firebase 回收器视图数据未显示我已尝试多种方式但找不到我的答案请帮助 我的 Firebase 回收站视图数据未显示我已尝试多种方式，但找不到我的答案，请帮助

Show_Activity.java

public class Show_Activity extends AppCompatActivity {
    private RecyclerView   recyclerView;
    private FirebaseDatabase db = FirebaseDatabase.getInstance();
    private DatabaseReference root = db.getReference().child("Matches");
    private MyAdapter adapter;
    private ArrayList<Model> list;

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

        recyclerView = findViewById(R.id.recyclerview);
        list = new ArrayList<>();

        root.addValueEventListener(new ValueEventListener() {
            @Override
            public void onDataChange(@NonNull DataSnapshot snapshot) {

                for (DataSnapshot dataSnapshot : snapshot.getChildren()){
                    Model model = dataSnapshot.getValue(Model.class);
                    list.add( new Model(model.matchname,model.bettingamt));
                    Log.i("THE_CURRENT_USER:::", model.toString());
                }
                LinearLayoutManager im = new LinearLayoutManager((Show_Activity.this));
                recyclerView.setLayoutManager(im);
                adapter = new MyAdapter(list);
                recyclerView.setAdapter(adapter);
            }

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

MyAdapter.java

public class MyAdapter extends RecyclerView.Adapter<MyAdapter.MyViewHolder> {
    ArrayList<Model> mList;
    Context context;

    public MyAdapter(Context context , ArrayList<Model> mList){    
        this.mList = mList;
        this.context = context;
    }

    public MyAdapter(ArrayList<Model> list) {

    }

    @NonNull
    @Override
    public MyViewHolder onCreateViewHolder(@NonNull ViewGroup parent, int viewType) {
        View v = LayoutInflater.from(context).inflate(R.layout.game , parent ,false);

return new MyViewHolder(v);

    }

    @Override
    public void onBindViewHolder(@NonNull MyViewHolder holder, int position) {
        Model model = mList.get(position);
        holder.matchname.setText(model.getMatchname());
        holder.bettingamount.setText(model.getBettingamt());
    }

    @Override
    public int getItemCount() {
        return mList.size();
    }
    public static  class MyViewHolder extends RecyclerView.ViewHolder{

        TextView matchname , bettingamount;

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

            matchname = itemView.findViewById(R.id.matchname);
            bettingamount = itemView.findViewById(R.id.bettingamt);
        }
    }
}

模型.java

public class Model {
    public String getMatchname() {
        return matchname;
    }

    public void setMatchname(String matchname) {
        this.matchname = matchname;
    }

    public String getBettingamt() {
        return bettingamt;
    }

    public void setBettingamt(String bettingamt) {
        this.bettingamt = bettingamt;
    }

    public Model(String matchname, String bettingamt) {
        this.matchname = matchname;
        this.bettingamt = bettingamt;
    }

    String matchname , bettingamt;
}

Answer 1

看看你的 MyAdapter 构造函数：

public MyAdapter(Context context , ArrayList<Model> mList){

        this.mList = mList;
        this.context = context;
    }

public MyAdapter(ArrayList<Model> list) {

    }

看看你在数据准备好后做什么：

adapter = new MyAdapter(list);

所以，你必须打电话给adapter = new MyAdapter(Show_Activity.this, list);

Answer 2

您还需要为模型类添加默认构造函数

public Model(){}

并将adapter = new MyAdapter(list); 更改为adapter = new MyAdapter(this,list);