RecyclerView.setAdapter(androidx.recyclerview.widget.RecyclerView 适配器适配器

Question

Tried using recycler view inside recycler view the first adapter works fine but the second adapter never runs tired fixing it over and over nothing works....help The second recycler view is retrieving data from Firebase

The Data from firebase is received but never set to the required text views.

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Activity

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public class ScheduleOrder extends AppCompatActivity implements IFirebaseLoadListener {

    DeviceSession deviceSession;
    UserSession userSession;
    String Device_Id="",User_Id="";
    MyItemAdapter myItemAdapter;
    IFirebaseLoadListener iFirebaseLoadListener;
    List<String> Name;
    List<ItemData>itemData;
    ItemData itemData1;
    RecyclerView my_recycler_view;

    DatabaseReference myData;



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

        itemData1=new ItemData();
        deviceSession = new DeviceSession(getApplicationContext());
        Device_Id = deviceSession.getDeviceDetails();

        userSession = new UserSession(getApplicationContext());
        final HashMap<String, String> user = userSession.getUserDetails();
        User_Id = user.get(UserSession.User_Id);

        FloatingActionButton myFab = (FloatingActionButton)findViewById(R.id.schedule_add);
        myFab.setOnClickListener(new View.OnClickListener() {
            public void onClick(View v) {
                Intent i = new Intent(getApplicationContext(),Schedule_Order.class);
                startActivity(i);
                finish();
            }
        });






        myData=FirebaseDatabase.getInstance().getReference("Cart_Schedule"+"/"+Device_Id);
        iFirebaseLoadListener=this;

        my_recycler_view=findViewById(R.id.my_recyclr_view);
        my_recycler_view.setHasFixedSize(true);
//        my_recycler_view1.setHasFixedSize(true);

        my_recycler_view.setLayoutManager(new LinearLayoutManager(this));
//        my_recycler_view1.setLayoutManager(new LinearLayoutManager(this));


        getFirebaseData();









    }

    private void getFirebaseData() {
        myData.addListenerForSingleValueEvent(new ValueEventListener() {
            @Override
            public void onDataChange(@NonNull DataSnapshot dataSnapshot) {
                List<ItemGroup>itemGroups=new ArrayList<>();

                Name=new ArrayList<>();
                for(DataSnapshot groupSnapShot:dataSnapshot.getChildren()){

                    ItemGroup itemGroup=new ItemGroup();

                    itemGroup.setD_Time(groupSnapShot.child("d_Time").getValue(true).toString());
                    itemGroup.setF_Amount(groupSnapShot.child("f_Amount").getValue(true).toString());

                    for(DataSnapshot newdatasnap:groupSnapShot.child("listItem").getChildren()){


                        itemData1.setA_Item_name(newdatasnap.child("a_Item_name").getValue().toString());
                        itemData1.setB_Quantity(newdatasnap.child("b_Quantity").getValue().toString());
                        itemData1.setC_Price(newdatasnap.child("b_Quantity").getValue().toString());
                        Name.add(newdatasnap.child("a_Item_name").getValue().toString());
                        Name.add(newdatasnap.child("c_Price").getValue().toString());
                        Name.add(newdatasnap.child("b_Quantity").getValue().toString());
                        Log.d("JADOO", "onDataChange: ??? "+itemData1.getA_Item_name());
                        Log.d("JADOO", "onDataChange: ??? "+itemData1.getB_Quantity());
                        Log.d("JADOO", "onDataChange: ??? "+itemData1.getC_Price());


                        Log.d("JADOO", "onDataChange: ??? "+Name);}


                    Log.d("JADOO", "onDataChange: ====================================================");

                    itemGroups.add(itemGroup);


                    Name.clear();
                }

                iFirebaseLoadListener.onFirebaseLoadSuccess(itemGroups);

            }

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

                iFirebaseLoadListener.onFirebaseLoadFailed(databaseError.getMessage());
            }
        });
    }


    @Override
    public void onFirebaseLoadSuccess(List<ItemGroup> itemGroupList) {
        Log.d("JADOO", "onDataChange: Setting Adapter");
        MyItemGroupAdapter adapter = new MyItemGroupAdapter(ScheduleOrder.this,itemGroupList,itemData1);
        my_recycler_view.setAdapter(adapter);

    }

    @Override
    public void onFirebaseLoadFailed(String message) {

    }


}

First Adapter Java file

public class MyItemGroupAdapter extends RecyclerView.Adapter<MyItemGroupAdapter.MyViewHolder> {
    private Context context;
    private List<ItemGroup>dataList;
    private ItemData name;
    public MyItemGroupAdapter(Context context, List<ItemGroup> dataList,ItemData data) {
        this.context = context;
        this.dataList = dataList;
        this.name=data;
    }
    @NonNull
    @Override
    public MyViewHolder onCreateViewHolder(@NonNull ViewGroup viewGroup, int i) {

        View itemView=LayoutInflater.from(context).inflate(R.layout.tempcartlayout,viewGroup,false);
        return new MyViewHolder(itemView);
    }
    @Override
    public void onBindViewHolder(@NonNull final MyViewHolder myViewHolder, int i) {
        MyItemAdapter itemListAdapter = new MyItemAdapter(context,name);
        myViewHolder.timee.setText(dataList.get(i).getD_Time());
        myViewHolder.cost.setText(dataList.get(i).getF_Amount());
        Log.d("JADOO", "onDataChange:  IN MY ITEM GRP ADAPTER "+name.getA_Item_name());
        myViewHolder.recycler_view_item_list.setHasFixedSize(true);
        myViewHolder.recycler_view_item_list.setLayoutManager(new CustomLinearLayoutManager(context,LinearLayoutManager.VERTICAL,false));
        myViewHolder.recycler_view_item_list.setAdapter(itemListAdapter);
        myViewHolder.recycler_view_item_list.setNestedScrollingEnabled(false);

        myViewHolder.can.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                Toast.makeText(context, "Button More : "+myViewHolder.timee.getText()+"  --  "+myViewHolder.cost.getText(), Toast.LENGTH_SHORT).show();
            }
        });
    }
    @Override
    public int getItemCount() {
        return (dataList != null ? dataList.size() : 0);
    }

    public class MyViewHolder extends RecyclerView.ViewHolder {

        TextView timee,cost;
        Button can;
        RecyclerView recycler_view_item_list;
        public MyViewHolder(@NonNull View itemView) {
            super(itemView);

            timee=itemView.findViewById(R.id.reorder_time);
            cost=itemView.findViewById(R.id.reorder_cost);
            can=itemView.findViewById(R.id.button);
            Log.d("JADOO", "onDataChange: VIEW HOLDER ");
            recycler_view_item_list=itemView.findViewById(R.id.schedulecart);
}}}

Second Adapter File

    private Context context;
    private ItemData name123;
    public MyItemAdapter(Context context, ItemData Item_Name) {
        this.context = context;
        this.name123=Item_Name;
    }
    @NonNull
    @Override
    public MyViewHolder onCreateViewHolder(@NonNull ViewGroup viewGroup, int i) {
        View itemView= LayoutInflater.from(context).inflate(R.layout.cart_list_layout,viewGroup,false);
        return new MyViewHolder(itemView);
    }
    @Override
    public void onBindViewHolder(@NonNull MyViewHolder myViewHolder, final int i) {
        Log.d("JADOO", "onBindViewHolder:  IN MY ITEM ADAPTER");
        ItemData itemData=new ItemData();
        myViewHolder.m_name.setText(itemData.getA_Item_name());
        myViewHolder.m_cost.setText(itemData.getC_Price());
        myViewHolder.m_quant.setText(itemData.getB_Quantity());
    }
    @Override
    public int getItemCount() {
        return 0;
    }

    public class MyViewHolder extends RecyclerView.ViewHolder implements View.OnClickListener {

        TextView m_name,m_quant,m_cost;
        IItemClickListener iItemClickListener;
        public void setiItemClickListener(IItemClickListener iItemClickListener){
            this.iItemClickListener=iItemClickListener;
        }
        public MyViewHolder(@NonNull View itemView) {
            super(itemView);

            m_name=itemView.findViewById(R.id.tv_menu_name1);
            m_quant=itemView.findViewById(R.id.quantity);
            m_cost=itemView.findViewById(R.id.amount);
            itemView.setOnClickListener(this);
        }
        @Override
        public void onClick(View view) {
            iItemClickListener.onItemClickListener(view,getAdapterPosition());
        }}}

Error

E/AndroidRuntime: FATAL EXCEPTION: main
    Process: com.food.pilo, PID: 28457
    java.lang.NullPointerException: Attempt to invoke virtual method 'void androidx.recyclerview.widget.RecyclerView.setAdapter(androidx.recyclerview.widget.RecyclerView$Adapter)' on a null object reference
        at com.food.pilo.ScheduleOrder.onFirebaseLoadSuccess(ScheduleOrder.java:161)
        at com.food.pilo.ScheduleOrder$2.onDataChange(ScheduleOrder.java:143)
        at com.google.firebase.database.Query$1.onDataChange(com.google.firebase:firebase-database@@16.0.4:183)
        at com.google.firebase.database.core.ValueEventRegistration.fireEvent(com.google.firebase:firebase-database@@16.0.4:75)
        at com.google.firebase.database.core.view.DataEvent.fire(com.google.firebase:firebase-database@@16.0.4:63)
        at com.google.firebase.database.core.view.EventRaiser$1.run(com.google.firebase:firebase-database@@16.0.4:55)
        at android.os.Handler.handleCallback(Handler.java:873)
        at android.os.Handler.dispatchMessage(Handler.java:99)
        at android.os.Looper.loop(Looper.java:214)
        at android.app.ActivityThread.main(ActivityThread.java:7156)
        at java.lang.reflect.Method.invoke(Native Method)
        at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:494)
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:975)```

Answer 1

Your return value is 0 in Second adapter. Please add arraylist to second adapter.

@Override
public int getItemCount() {
    return 0;
}

Answer 2

I think my_recycler_view=findViewById(R.id.my_recyclr_view); or

findViewById(R.id.schedulecart); returning null please check on these lines.