Android RecyclerView嵌套EditView实时更新Item数据

一、场景（例如：购物车）

1、当我们需要以列表样式管理某些数据时，可能需要列表项的某个字段可编辑

2、编辑Item上的某个字段后可能还要更新相关字段的值

二、可能遇到的问题

1、列表滑动导致输入框中的数据错位（或者焦点错位）

2、无法更新Item上相关的字段项的值

3、监听输入框文本更改时陷入死循环

三、可行方案（RecyclerView+TextWatcher）

       1、用RecyclerView 实现一个ListView的效果：

package com.zhn.edit.recycler;

import android.os.Bundle;
import android.support.design.widget.FloatingActionButton;
import android.support.design.widget.Snackbar;
import android.support.v7.app.AppCompatActivity;
import android.support.v7.widget.LinearLayoutManager;
import android.support.v7.widget.RecyclerView;
import android.support.v7.widget.Toolbar;
import android.util.Log;
import android.view.View;
import android.view.Menu;
import android.view.MenuItem;

import java.util.ArrayList;
import java.util.List;

public class MainActivity extends AppCompatActivity implements View.OnClickListener,
        EditAbleListAdapter.EditAbleListAdapterListener{

    private FloatingActionButton mFLoatingBtnEmail;

    private RecyclerView mRecyclerEditAble;
    private LinearLayoutManager mEditAbleLayoutManager;
    private EditAbleListAdapter mEditAbleListAdapter;
    private List<datagoods> mDataGoods=new ArrayList<datagoods>();

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

        mFLoatingBtnEmail = (FloatingActionButton) findViewById(R.id.floating_btn_email);
        mFLoatingBtnEmail.setOnClickListener(this);

        mRecyclerEditAble= (RecyclerView) findViewById(R.id.recycler_editable);

        initData();

    }

    private void initData() {
        mEditAbleLayoutManager=new LinearLayoutManager(this,LinearLayoutManager.VERTICAL,false);
        mRecyclerEditAble.setLayoutManager(mEditAbleLayoutManager);
        mEditAbleListAdapter=new EditAbleListAdapter(this,this);
        mRecyclerEditAble.setAdapter(mEditAbleListAdapter);

        for (int i=;i<;i++){
            mDataGoods.add(new DataGoods("Goods"+i,i,i,i*i));
        }

        mEditAbleListAdapter.refreshDatas(mDataGoods);
    }

    @Override
    public void onClick(View v) {
        switch (v.getId()) {
            case R.id.floating_btn_email:
                for (int i=;i<mdatagoods.size();i++){ 
　　　　　　　　　　　　log.e(mainactivity.class.getsimplename(),mdatagoods.get(i).tostring());="" }="" break;="" default:="" @override="" public="" void="" onedittextchanged(int="" position,="" string="" value)="" {="" todo="" 此处或者回调前应做值合法性验证="" mdatagoods.get(position).setnum(integer.parseint(value));="" <="" pre=""></mdatagoods.size();i++){></datagoods></datagoods>

2、在Adapter中自定义一个Interface 用来将输入的值回传给Activity

3、定义TxtWatcher 接收position和要同步更新的文本框

4、给EditText添加焦点变化的监听器，根据焦点状态绑定和解绑TxtWatcher

package com.zhn.edit.recycler;

import android.content.Context;
import android.support.v7.widget.RecyclerView;
import android.text.Editable;
import android.text.TextWatcher;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.EditText;
import android.widget.TextView;

import java.util.ArrayList;
import java.util.List;

/**
 * Created by zhn
 * 2017/7/9 下午4:20
 */
public class EditAbleListAdapter extends RecyclerView.Adapter{

    public void refreshDatas(List<datagoods> mDataGoods) {
        mDatas.clear();
        mDatas.addAll(mDataGoods);
        notifyDataSetChanged();
    }

    public interface EditAbleListAdapterListener{
        public void onEditTextChanged(int position,String value);
    }

    private Context mContext;
    private List<datagoods> mDatas=new ArrayList<datagoods>();

    private EditAbleListAdapterListener mListener;
    public EditAbleListAdapter(Context context,EditAbleListAdapterListener listener){
        this.mContext=context;
        this.mListener=listener;
    }

    @Override
    public RecyclerView.ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
        return new EditAbleListViewHolder(LayoutInflater.from(mContext).inflate(R.layout.item_editable_view,null));
    }

    @Override
    public void onBindViewHolder(RecyclerView.ViewHolder holder, int position) {
        ((EditAbleListViewHolder)holder).setContent(position,mDatas.get(position));

    }

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

    public class EditAbleListViewHolder extends RecyclerView.ViewHolder{

        private TextView mTvItemNo;
        private TextView mTvGoodsName;
        private TextView mTvPrice;
        private EditText mEtNum;
        private TextView mTvTotalPrice;

        private TxtWatcher mTxtWatcher;

        public EditAbleListViewHolder(View itemView) {
            super(itemView);

            mTvItemNo= (TextView) itemView.findViewById(R.id.tv_item_no);
            mTvGoodsName= (TextView) itemView.findViewById(R.id.tv_goods_name);
            mTvPrice= (TextView) itemView.findViewById(R.id.tv_price);
            mEtNum= (EditText) itemView.findViewById(R.id.et_num);
            mTvTotalPrice= (TextView) itemView.findViewById(R.id.tv_total_price);

            mTxtWatcher=new TxtWatcher();
        }

        public void setContent(int position,DataGoods data){

            mTvItemNo.setText(String.valueOf(position+));
            mTvGoodsName.setText(data.getGoodsName());
            mTvPrice.setText(String.valueOf(data.getPrice()));
            mEtNum.setText(String.valueOf(data.getNum()));
            mTvTotalPrice.setText(String.valueOf(data.getTotalPrice()));

            mTxtWatcher.buildWatcher(position,mTvTotalPrice);

            mEtNum.setOnFocusChangeListener(new View.OnFocusChangeListener() {
                @Override
                public void onFocusChange(View v, boolean hasFocus) {
                    if(hasFocus){
                        mEtNum.addTextChangedListener(mTxtWatcher);
                    }else{
                        mEtNum.removeTextChangedListener(mTxtWatcher);
                    }
                }
            });
        }

    }

    public class TxtWatcher implements TextWatcher{

        private int mPosition;
        private TextView mTvTotalPrice;

        public void buildWatcher(int position,TextView view){
            this.mPosition=position;
            this.mTvTotalPrice=view;
        }

        @Override
        public void beforeTextChanged(CharSequence s, int start, int count, int after) {

        }

        @Override
        public void onTextChanged(CharSequence s, int start, int before, int count) {
            if(s.length()>){
                if(mListener!=null){
                    mListener.onEditTextChanged(mPosition,s.toString());
                    mTvTotalPrice.setText(String.valueOf(mDatas.get(mPosition).getPrice()*Double.parseDouble(s.toString())));
                }
            }else{
                if(mListener!=null){
                    mListener.onEditTextChanged(mPosition,"");
                    mTvTotalPrice.setText("");
                }
            }
        }

        @Override
        public void afterTextChanged(Editable s) {

        }
    }

}

四、选择RecyclerView而不是ListView的原因

        RecyclerView 在滑动的时候会使EditText失去焦点，这样可以触发OnFocusChangeListener，这样可以更准确的绑定和解绑TxtWatcher。为什么要解绑TxtWatcher？因为在RecyclerView刷新的时候会重复触发TextWatcher导致很多次无用的回调（甚至死循环）。

ListView在滑动的时候不会使EditText失去焦点，导致了滑动时输入框焦点错位，并且因为输入框是复用的所以导致TextWatcher重复触发很多次（可能是死循环）。

五、注意在布局中设置列表是尽量降低RecyclerView布局重绘的可能性（例如：固定大小等等）