获取Recycler视图Edittext的总和并更新父布局（自定义适配器）

Question

如何从Recycler视图适配器访问父布局。我的目标是在Recycler视图中获取qty的总和并更新父级中的小计。

这是我的代码。

这是主要活动

public class project_bid extends AppCompatActivity {

DatabaseReference mRef;
RecyclerView ItemRecyclerView;
EditText subtotal, tax, grandTotal;
String key;
LinearLayout bid_total_layout;
projectItemAdapter adapter;

@Override
protected void onCreate(Bundle savedInstanceState) {
    key = getIntent().getStringExtra("key");
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_project_bid);

    mRef = FirebaseDatabase.getInstance().getReference().child("projects/1/project_line");

    subtotal = (EditText) findViewById(R.id.project_bid_subtotal);
    tax = (EditText) findViewById(R.id.project_bid_tax);
    grandTotal = (EditText) findViewById(R.id.project_bid_grandTotal);
    bid_total_layout = (LinearLayout) findViewById(R.id.project_bid_total_layout);

    ItemRecyclerView = (RecyclerView) findViewById(R.id.projectRecycler);
    ItemRecyclerView.setHasFixedSize(false);
    ItemRecyclerView.setLayoutManager(new LinearLayoutManager(this));


    mRef.addValueEventListener(new ValueEventListener() {
        @Override
        public void onDataChange(DataSnapshot dataSnapshot) {
            ArrayList<ProjectDetailsLineBuilder> list = new ArrayList<ProjectDetailsLineBuilder>();
            for (DataSnapshot snapshot: dataSnapshot.getChildren()){
                ProjectDetailsLineBuilder item = snapshot.getValue(ProjectDetailsLineBuilder.class);
                list.add(item);
            }
            adapter = new projectItemAdapter(list, project_bid.this);
            ItemRecyclerView.setAdapter(adapter);
        }
        @Override
        public void onCancelled(DatabaseError databaseError) {

        }
    });

}


@Override
protected void onStart() {
    super.onStart();

}

另外，我使用上面的方法来获取并将值传递给适配器。 for循环会产生性能问题，还有更好的解决方案吗？

这是我的适配器和视图持有者类。

public class projectItemAdapter  extends RecyclerView.Adapter<projectItemAdapter.projectBidItems>{
ArrayList<ProjectDetailsLineBuilder> data;
Context context;
LinearLayout totalLayout;

public projectItemAdapter(ArrayList<ProjectDetailsLineBuilder> data, Context context) {
    this.data = data;
    this.context = context;
}



@Override
public projectBidItems onCreateViewHolder(ViewGroup parent, int viewType) {
    View v = LayoutInflater.from(context).inflate(R.layout.project_bid_line, parent, false);
    View main = LayoutInflater.from(context).inflate(R.layout.activity_project_bid, parent, false);
    return new projectBidItems(v);

}

@Override
public void onBindViewHolder(projectBidItems holder, int position) {
    ProjectDetailsLineBuilder item = data.get(position);
    holder.qty.setText(String.valueOf(item.getQuantity()));
    holder.quantity.setText("Quantity: 20 " + item.getUnit());
    holder.title.setText(item.getTitle());
    holder.desc.setText(item.getDescription());
    holder.unitprice.setOnFocusChangeListener(new View.OnFocusChangeListener() {
        @Override
        public void onFocusChange(View view, boolean b) {
            if(b){

            }
        }
    });
}

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


public static class projectBidItems extends RecyclerView.ViewHolder {
    View mView;
    EditText qty;
    EditText total, unitprice;
    TextView quantity, desc, title;


    public projectBidItems(View item) {
        super(item);
        mView = item;

        unitprice = (EditText) mView.findViewById(R.id.project_line_unit_price);
        total = (EditText) mView.findViewById(R.id.project_line_total);
        quantity = (TextView) mView.findViewById(R.id.project_line_qty);
        qty = (EditText) mView.findViewById(R.id.project_line_cal_qty);
        title = (TextView) mView.findViewById(R.id.project_line_title);
        desc = (TextView) mView.findViewById(R.id.project_lined_description);

    }

}

}