▲ Android 常用购物车常用样式（单商家/多商家）功能实现

一朋友管我要个单商家的购物车实现功能，我说这个东西不很简单嘛，他说你干了这么久了连一个购物车的模板都没有吗？他这句引起了我的反思，购物车用的时候很少，基本每次都是现写，这样确实花费了不少时间，如果有一个现成的Demo或者模板，任何开发者拿过来只需要简单的改一改，马上就可以应用，想必也是极好的。

下面我说两种常见的样式，一种是单商家的购物车，另外一种类似淘宝那种多商家那种购物车。

**

单商家购物车

老规矩先上图

长按Item删除

主页代码实现

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

    }


    private void initView() {
        initData();
        initAdapter();
        tvGoodsMoney = findViewById(R.id.tv_goods_money);
        tvMoney = findViewById(R.id.tv_money);
        allCheckBox = findViewById(R.id.all_checkBox);

        rl_no_data_a = findViewById(R.id.rl_no_data_a);
        rl_no_data_b = findViewById(R.id.rl_no_data_b);

        allCheckBox.setOnClickListener(this);
        llView = findViewById(R.id.ll_layout);


    }


    private void initData() {
        list = new ArrayList<>();
        list.add(new AloneShopBean("1", "架豆王", "辽宁沈阳新鲜蔬菜", 1, "30.00"));
        list.add(new AloneShopBean("2", "架豆王(精品)", "新鲜蔬菜", 1, "50.00"));
        list.add(new AloneShopBean("3", "架豆王", "蔬菜不隔夜，联系方式xxx", 2, "25.00"));
        list.add(new AloneShopBean("4", "架豆王(良品)", "欢迎采购", 1, "35.00"));
        list.add(new AloneShopBean("5", "架豆王", "蔬菜不隔夜，联系方式xxx", 2, "25.00"));


    }

    /**
     * 初始化适配器
     */
    private void initAdapter() {

        RecyclerView rcList = findViewById(R.id.rc_list);
        rcList.setLayoutManager(new LinearLayoutManager(AloneShopActivity.this));
        adapterX = new AloneShopAdapter(R.layout.item_shop_car, list);
        adapterX.setCheckInterface(this);
        adapterX.setModifyCountInterface(this);
        rcList.setAdapter(adapterX);
        //长按删除
        adapterX.setOnItemLongClickListener(new BaseQuickAdapter.OnItemLongClickListener() {
            @Override
            public boolean onItemLongClick(BaseQuickAdapter adapter, View view, int position) {
                ISDelete(position);
                return true;

            }
        });

    }

    private void ISDelete(final int position) {

        final View contentView = LayoutInflater.from(AloneShopActivity.this).inflate(R.layout.dialog_windows_delete, null);
        mCustomPopWindowCause = new CustomPopWindow.PopupWindowBuilder(AloneShopActivity.this)
                .setView(contentView)
                .enableBackgroundDark(true) //弹出popWindow时，背景是否变暗
                .setBgDarkAlpha(0.6f) // 控制亮度
                .enableOutsideTouchableDissmiss(true)
                .create();
        mCustomPopWindowCause.showAtLocation(llView, Gravity.CENTER, 0, 0);
        contentView.findViewById(R.id.dialog_btn_cancel).setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                mCustomPopWindowCause.dissmiss();
            }
        });
        contentView.findViewById(R.id.dialog_btn_sure).setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                list.remove(position);
                mCustomPopWindowCause.dissmiss();
                adapterX.notifyDataSetChanged();

            }
        });


    }

    @Override
    public void onClick(View v) {
        switch (v.getId()) {
            case R.id.all_checkBox:
                doCheckAll();
                break;

            case R.id.tv_close_k:
                //结算逻辑
                break;
        }


    }

    @Override
    public void checkGroup(int groupPosition, boolean isChecked) {
        list.get(groupPosition).setChecked(isChecked);

        if (isCheckAll()) {
            allCheckBox.setChecked(true);//全选
        } else {
            allCheckBox.setChecked(false);//反选
        }

        adapterX.notifyDataSetChanged();

        calulate();
    }


    /**
     * @return 判断组元素是否全选
     */
    private boolean isCheckAll() {

        for (AloneShopBean group : list) {
            if (!group.isChecked()) {
                return false;
            }
        }
        return true;
    }

    @Override
    public void doIncrease(int groupPosition, View showCountView, boolean isChecked) {
        AloneShopBean good = adapterX.getData().get(groupPosition);
        int count = good.getNum();
        count++;
        good.setNum(count);
        ((TextView) showCountView).setText(String.valueOf(count));
        adapterX.notifyDataSetChanged();
        calulate();
    }

    @Override
    public void doDecrease(int groupPosition, View showCountView, boolean isChecked) {
        AloneShopBean good = adapterX.getData().get(groupPosition);
        int count = good.getNum();
        if (count == 1) {
            return;
        }
        count--;
        good.setNum(count);
        ((TextView) showCountView).setText("" + count);
        adapterX.notifyDataSetChanged();
        calulate();
    }

    @Override
    public void childDelete(int groupPosition) {
        calulate();
    }

    private void doCheckAll() {
        for (int i = 0; i < list.size(); i++) {
            AloneShopBean group = list.get(i);
            group.setChecked(allCheckBox.isChecked());
        }
        adapterX.notifyDataSetChanged();
        calulate();
    }


    private void calulate() {
        mtotalPrice = 0.00;

        for (int i = 0; i < list.size(); i++) {
            AloneShopBean goods = list.get(i);
            if (goods.isChecked()) {
                BigDecimal b1 = new BigDecimal(goods.getMoney());
                BigDecimal b2 = new BigDecimal(goods.getNum() + "");
                mtotalPrice += b1.multiply(b2).doubleValue();
            }

        }
        String format = String.format("%.2f", mtotalPrice);
        tvMoney.setText("¥ " + format);
        tvGoodsMoney.setText("商品合计: ¥ " + format);

    }

适配器代码实现

public class AloneShopAdapter extends BaseQuickAdapter<AloneShopBean, BaseViewHolder> {

    private CheckInterface checkInterface;
    private ModifyCountInterface modifyCountInterface;
    private TextView tvNumber;

    public AloneShopAdapter(int layoutResId, @Nullable List<AloneShopBean> data) {
        super(layoutResId, data);
    }

    @Override
    protected void convert(final BaseViewHolder helper, final AloneShopBean item) {
        final CheckBox singleCheckBox = helper.getView(R.id.single_check_box);
        ImageView ivAdd = helper.getView(R.id.iv_add);
        ImageView ivMinus = helper.getView(R.id.iv_minus);
        tvNumber = helper.getView(R.id.tv_number);
        tvNumber.setText(String.valueOf(item.getNum()));
        helper.setText(R.id.tv_goods_name, item.getName())
                .setText(R.id.tv_describe, item.getDescribe());

        String price = item.getMoney();
        StringBuffer stringBuffer = new StringBuffer();
        stringBuffer.append("¥").append(price);
        SpannableString spannableString = new SpannableString(stringBuffer);
        AbsoluteSizeSpan absoluteSizeSpan17 = new AbsoluteSizeSpan(AutoSizeUtils.sp2px(mContext, 17));
        AbsoluteSizeSpan absoluteSizeSpan14 = new AbsoluteSizeSpan(AutoSizeUtils.sp2px(mContext, 14));
        spannableString.setSpan(absoluteSizeSpan17, 0, stringBuffer.indexOf("."), Spanned.SPAN_INCLUSIVE_INCLUSIVE);
        spannableString.setSpan(absoluteSizeSpan14, stringBuffer.indexOf("."), stringBuffer.length(), Spanned.SPAN_EXCLUSIVE_EXCLUSIVE);
        helper.setText(R.id.price, spannableString);

        singleCheckBox.setChecked(item.isChecked());
        singleCheckBox.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                item.setChecked(((CheckBox) v).isChecked());
                singleCheckBox.setChecked(((CheckBox) v).isChecked());
                checkInterface.checkGroup(helper.getLayoutPosition(), ((CheckBox) v).isChecked());
            }
        });

        ivAdd.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                modifyCountInterface.doIncrease(helper.getLayoutPosition(), tvNumber, singleCheckBox.isChecked());
            }
        });
        ivMinus.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                modifyCountInterface.doDecrease(helper.getLayoutPosition(), tvNumber, singleCheckBox.isChecked());
            }
        });
    }


    public CheckInterface getCheckInterface() {
        return checkInterface;
    }

    public void setCheckInterface(CheckInterface checkInterface) {
        this.checkInterface = checkInterface;
    }

    public ModifyCountInterface getModifyCountInterface() {
        return modifyCountInterface;
    }

    public void setModifyCountInterface(ModifyCountInterface modifyCountInterface) {
        this.modifyCountInterface = modifyCountInterface;
    }

    /**
     * 店铺的复选框
     */
    public interface CheckInterface {
        /**
         * 组选框状态改变触发的事件
         *
         * @param groupPosition 组元素的位置
         * @param isChecked     组元素的选中与否
         */
        void checkGroup(int groupPosition, boolean isChecked);

    }


    /**
     * 改变数量的接口
     */
    public interface ModifyCountInterface {
        /**
         * 增加操作
         *
         * @param groupPosition 组元素的位置
         * @param showCountView 用于展示变化后数量的View
         * @param isChecked     子元素选中与否
         */
        void doIncrease(int groupPosition, View showCountView, boolean isChecked);

        void doDecrease(int groupPosition, View showCountView, boolean isChecked);


        /**
         * 删除子Item
         *
         * @param groupPosition
         *
         */
        void childDelete(int groupPosition);
    }


}

多商家购物车

还是老规矩


主页代码实现

  @Override
    protected void onCreate(@Nullable Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_multi_shop);
        initView();
        initPtrFrame();
        initData();
        initAdapter();
    }


    private void initPtrFrame() {
        final PtrClassicDefaultHeader header = new PtrClassicDefaultHeader(this);
        header.setPadding(dp2px(20), dp2px(20), 0, 0);
        mPtrFrame.setHeaderView(header);
        mPtrFrame.addPtrUIHandler(header);
        mPtrFrame.setPtrHandler(new PtrDefaultHandler() {
            @Override
            public void onRefreshBegin(PtrFrameLayout frame) {
                mPtrFrame.postDelayed(new Runnable() {
                    @Override
                    public void run() {
                        mPtrFrame.refreshComplete();
                    }
                }, 2000);
            }

            @Override
            public boolean checkCanDoRefresh(PtrFrameLayout frame, View content, View header) {
                return PtrDefaultHandler.checkContentCanBePulledDown(frame, content, header);
            }
        });
    }


    private void initView() {
        headRight = findViewById(R.id.head_right);
        headRight.setVisibility(View.VISIBLE);
        headRight.setOnClickListener(this);
        listView = findViewById(R.id.listView);
        allCheckBox = findViewById(R.id.all_checkBox);
        allCheckBox.setOnClickListener(this);

        tvPrice = findViewById(R.id.tv_price);
        llCalculate = findViewById(R.id.ll_calculate);
        llCalculate.setOnClickListener(this);

        rlOrderInfo = findViewById(R.id.rl_order_info);
        llDelete = findViewById(R.id.ll_delete);
        llDelete.setOnClickListener(this);

        rlDeleteInfo = findViewById(R.id.rl_delete_info);
        llCart = findViewById(R.id.ll_cart);
        mPtrFrame = findViewById(R.id.mPtrframe);
        llBottomView = findViewById(R.id.ll_bottom_view);
        empty_shopcart = findViewById(R.id.layout_empty_shop);

    }

    /**
     * 初始化数据
     */
    private void initData() {
        hashMapGoodsId = new HashMap<>();
        xc = new ArrayList<>();//与Demo 无关
        groups = new ArrayList<StoreBean>();
        childs = new HashMap<>();
        for (int i = 0; i < 3; i++) {
            groups.add(new StoreBean(i + "", "天字第" + i + "号店铺"));
            List<MultiGoodsBean> goods = new ArrayList<>();
            goods.add(new MultiGoodsBean("1", "架豆王", "辽宁沈阳新鲜蔬菜", 1, "30.00"));
            goods.add(new MultiGoodsBean("2", "架豆王(精品)", "新鲜蔬菜", 1, "50.00"));
            goods.add(new MultiGoodsBean("3", "架豆王", "蔬菜不隔夜，联系方式xxx", 2, "25.00"));
            goods.add(new MultiGoodsBean("4", "架豆王(良品)", "欢迎采购", 1, "35.00"));

            childs.put(groups.get(i).getId(), goods);
        }


    }


    private void initAdapter() {
        adapterX = new MultiShopAdapter(groups, childs, MultiShopActivity.this);
        adapterX.setCheckInterface(this);//关键步骤1：设置复选框的接口
        adapterX.setModifyCountInterface(this); //关键步骤2:设置增删减的接口
        listView.setGroupIndicator(null); //设置属性 GroupIndicator 去掉向下箭头
        listView.setAdapter(adapterX);
        for (int i = 0; i < adapterX.getGroupCount(); i++) {
            listView.expandGroup(i); //关键步骤4:初始化，将ExpandableListView以展开的方式显示
        }

        listView.setOnScrollListener(new AbsListView.OnScrollListener() {
            @Override
            public void onScrollStateChanged(AbsListView view, int scrollState) {

            }

            @Override
            public void onScroll(AbsListView view, int firstVisibleItem, int visibleItemCount, int totalItemCount) {
                int top = -1;
                View firstView = view.getChildAt(firstVisibleItem);
                if (firstView != null) {
                    top = firstView.getTop();
                }
                if (firstVisibleItem == 0 && top == 0) {
                    mPtrFrame.setEnabled(true);
                } else {
                    mPtrFrame.setEnabled(false);
                }
            }
        });
    }

    @Override
    public void onClick(View v) {
        AlertDialog dialog;
        switch (v.getId()) {
            case R.id.head_right:
                flag = !flag;
                setVisibilityX();
                break;

            case R.id.all_checkBox:
                doCheckAll();
                break;

            case R.id.ll_calculate:
                GetGoodsId();
                if (xc.size() == 0) {
                    ToastUtilsX.showShortToast(MultiShopActivity.this, "请选择您要结算的商品！");
                    return;
                }
                //结算操作。。。。
                break;

            case R.id.ll_delete:
                if (mtotalCount == 0) {
                    ToastUtilsX.showLongToast(MultiShopActivity.this, "请选择要删除的商品!");
                    return;
                }
                dialog = new AlertDialog.Builder(MultiShopActivity.this).create();
                dialog.setMessage("确认要删除该商品吗?");
                dialog.setButton(DialogInterface.BUTTON_POSITIVE, "确定", new DialogInterface.OnClickListener() {
                    @Override
                    public void onClick(DialogInterface dialog, int which) {
                        doDelete();
                    }
                });
                dialog.setButton(DialogInterface.BUTTON_NEGATIVE, "取消", new DialogInterface.OnClickListener() {
                    @Override
                    public void onClick(DialogInterface dialog, int which) {
                        return;
                    }
                });
                dialog.show();
                break;

        }
    }


    /**
     * @return 判断组元素是否全选
     */
    private boolean isCheckAll() {
        hashMapGoodsId.clear();
        for (StoreBean group : groups) {
            if (!group.isChecked()) {
                return false;
            }
        }
        return true;
    }


    /**
     * 删除操作
     * 1.不要边遍历边删除,容易出现数组越界的情况
     * 2.把将要删除的对象放进相应的容器中，待遍历完，用removeAll的方式进行删除
     */
    private void doDelete() {
        List<StoreBean> toBeDeleteGroups = new ArrayList<StoreBean>(); //待删除的组元素
        for (int i = 0; i < groups.size(); i++) {
            StoreBean group = groups.get(i);
            if (group.isChecked()) {
                toBeDeleteGroups.add(group);
            }
            List<MultiGoodsBean> toBeDeleteChilds = new ArrayList<MultiGoodsBean>();//待删除的子元素
            List<MultiGoodsBean> child = childs.get(group.getId());
            for (int j = 0; j < child.size(); j++) {
                if (child.get(j).isChecked()) {
                    toBeDeleteChilds.add(child.get(j));
                }
            }
            //获取购物车ID 与Demo 没有关系
            GetGoodsId();
            child.removeAll(toBeDeleteChilds);
        }
        groups.removeAll(toBeDeleteGroups);
        //重新设置购物车
        setCartNum();
        adapterX.notifyDataSetChanged();

    }


    @Override
    public void checkGroup(int groupPosition, boolean isChecked) {
        hashMapGoodsId.clear();
        StoreBean group = groups.get(groupPosition);
        List<MultiGoodsBean> child = childs.get(group.getId());
        for (int i = 0; i < child.size(); i++) {
            child.get(i).setChecked(isChecked);
        }
        if (isCheckAll()) {
            allCheckBox.setChecked(true);//全选
        } else {
            allCheckBox.setChecked(false);//反选
        }
        adapterX.notifyDataSetChanged();
        calulate();
    }

    @Override
    public void checkChild(int groupPosition, int childPosition, boolean isChecked) {
        hashMapGoodsId.clear();
        boolean allChildSameState = true; //判断该组下面的所有子元素是否处于同一状态
        StoreBean group = groups.get(groupPosition);
        List<MultiGoodsBean> child = childs.get(group.getId());
        for (int i = 0; i < child.size(); i++) {
            //不选全中
            if (child.get(i).isChecked() != isChecked) {
                allChildSameState = false;
                break;
            }
        }

        if (allChildSameState) {
            group.setChecked(isChecked);//如果子元素状态相同，那么对应的组元素也设置成这一种的同一状态
        } else {
            group.setChecked(false);//否则一律视为未选中
        }

        if (isCheckAll()) {
            allCheckBox.setChecked(true);//全选
        } else {
            allCheckBox.setChecked(false);//反选
        }

        adapterX.notifyDataSetChanged();
        calulate();
    }


    @Override
    public void doIncrease(int groupPosition, int childPosition, View showCountView, boolean isChecked) {
        MultiGoodsBean good = (MultiGoodsBean) adapterX.getChild(groupPosition, childPosition);
        int count = good.getNum();
        count++;
        good.setNum(count);
        ((TextView) showCountView).setText(String.valueOf(count));
        adapterX.notifyDataSetChanged();
        calulate();
    }

    @Override
    public void doDecrease(int groupPosition, int childPosition, View showCountView, boolean isChecked) {
        MultiGoodsBean good = (MultiGoodsBean) adapterX.getChild(groupPosition, childPosition);
        int count = good.getNum();
        if (count == 1) {
            return;
        }
        count--;
        good.setNum(count);
        ((TextView) showCountView).setText("" + count);
        adapterX.notifyDataSetChanged();
        calulate();
    }

    @Override
    public void doUpdate(int groupPosition, int childPosition, View showCountView, boolean isChecked) {
        MultiGoodsBean good = (MultiGoodsBean) adapterX.getChild(groupPosition, childPosition);
        int count = good.getNum();
        ((TextView) showCountView).setText(String.valueOf(count));
        adapterX.notifyDataSetChanged();
        calulate();
    }

    @Override
    public void childDelete(int groupPosition, int childPosition) {
        StoreBean group = groups.get(groupPosition);
        List<MultiGoodsBean> child = childs.get(group.getId());
        child.remove(childPosition);
        if (child.size() == 0) {
            groups.remove(groupPosition);
        }
        adapterX.notifyDataSetChanged();
        calulate();
    }

    /**
     * 全选和反选
     */
    private void doCheckAll() {
        for (int i = 0; i < groups.size(); i++) {
            StoreBean group = groups.get(i);
            group.setChecked(allCheckBox.isChecked());
            List<MultiGoodsBean> child = childs.get(group.getId());
            for (int j = 0; j < child.size(); j++) {
                child.get(j).setChecked(allCheckBox.isChecked());
            }
        }
        adapterX.notifyDataSetChanged();
        calulate();
    }


    /**
     * 计算商品总价格，操作步骤
     * 1.先清空全局计价,计数
     * 2.遍历所有的子元素，只要是被选中的，就进行相关的计算操作
     * 3.给textView填充数据
     */
    private void calulate() {
        mtotalPrice = 0.00;
        mtotalCount = 0;
        for (int i = 0; i < groups.size(); i++) {
            StoreBean group = groups.get(i);
            List<MultiGoodsBean> child = childs.get(group.getId());
            for (int j = 0; j < child.size(); j++) {
                MultiGoodsBean good = child.get(j);
                if (good.isChecked()) {
                    mtotalCount++;

                    BigDecimal b1 = new BigDecimal(good.getMoney());
                    BigDecimal b2 = new BigDecimal(good.getNum() + "");
                    mtotalPrice += b1.multiply(b2).doubleValue();

                }
            }
        }
        String resultX = String.format("%.2f", mtotalPrice);
        tvPrice.setText("￥" + resultX);


        if (mtotalCount == 0) {
            setCartNum();
        }

    }


    /**
     * 显示/隐藏
     */
    private void setVisibilityX() {
        if (flag) {
            rlOrderInfo.setVisibility(View.GONE);
            rlDeleteInfo.setVisibility(View.VISIBLE);
            headRight.setText("完成");
        } else {
            rlOrderInfo.setVisibility(View.VISIBLE);
            rlDeleteInfo.setVisibility(View.GONE);
            headRight.setText("管理");
        }
    }


    /**
     * 设置购物车的数量
     */
    private void setCartNum() {
        int count = 0;
        for (int i = 0; i < groups.size(); i++) {
            StoreBean group = groups.get(i);
            group.setChecked(allCheckBox.isChecked());
            List<MultiGoodsBean> Childs = childs.get(group.getId());
            for (MultiGoodsBean childs : Childs) {
                count++;
            }
        }

        //购物车已经清空
        if (count == 0) {
            clearCart();
        } else {
            headRight.setVisibility(View.VISIBLE);
            empty_shopcart.setVisibility(View.GONE);//这里发生过错误
            llBottomView.setVisibility(View.VISIBLE);
        }

    }


    private void clearCart() {
        empty_shopcart.setVisibility(View.VISIBLE);//这里发生过错误
        headRight.setVisibility(View.GONE);
        llBottomView.setVisibility(View.GONE);
    }


    @Override
    public void onDestroy() {
        super.onDestroy();
        adapterX = null;
        childs.clear();
        groups.clear();
        mtotalPrice = 0.0;
        mtotalCount = 0;

    }


    //获取购物车ID 的拼接
    private void GetGoodsId() {
        StringBuffer permission = new StringBuffer();
        List<StoreBean> toBeDeleteGroups = new ArrayList<StoreBean>(); //待删除的组元素

        for (int i = 0; i < groups.size(); i++) {
            StoreBean group = groups.get(i);
            if (group.isChecked()) {
                toBeDeleteGroups.add(group);
                xc.add(group);
            }
            List<MultiGoodsBean> toBeDeleteChilds = new ArrayList<MultiGoodsBean>();//复用获取ID

            List<MultiGoodsBean> child = childs.get(group.getId());

            for (int j = 0; j < child.size(); j++) {
                if (child.get(j).isChecked()) {
                    toBeDeleteChilds.add(child.get(j));

                }
            }

            for (int k = 0; k < toBeDeleteChilds.size(); k++) {
                permission.append(toBeDeleteChilds.get(k).getId() + ",");
                hashMapGoodsId.put(toBeDeleteChilds.get(k).getId(), toBeDeleteChilds.get(k).getId());
            }


            if (permission.toString().length() > 0) {
                String strX = permission.toString();
                // 拼接完成的商品购物车ID
                String goodsId = strX.substring(0, strX.length() - 1);
            }


        }
    }

多商家适配器代码实现

public class MultiShopAdapter extends BaseExpandableListAdapter {

    private List<StoreBean> groups;
    //这个String对应着StoreInfo的Id，也就是店铺的Id
    private Map<String, List<MultiGoodsBean>> childrens;
    private Context mcontext;
    private CheckInterface checkInterface;
    private ModifyCountInterface modifyCountInterface;

    public MultiShopAdapter(List<StoreBean> groups, Map<String, List<MultiGoodsBean>> childrens, Context mcontext) {
        this.groups = groups;
        this.childrens = childrens;
        this.mcontext = mcontext;
    }


    @Override
    public int getGroupCount() {
        return groups == null ? 0 : groups.size();
    }

    @Override
    public int getChildrenCount(int groupPosition) {
        String groupId = groups.get(groupPosition).getId();
        return childrens.get(groupId).size();
    }

    @Override
    public Object getGroup(int groupPosition) {
        if (groups.size() == 0) {

            return "";
        } else {
            return groups.get(groupPosition);
        }
    }

    @Override
    public Object getChild(int groupPosition, int childPosition) {
        if (groups.size() == 0) {
            return "";
        } else {
            List<MultiGoodsBean> childs = childrens.get(groups.get(groupPosition).getId());
            return childs.get(childPosition);
        }
    }

    @Override
    public long getGroupId(int groupPosition) {
        return groupPosition;
    }

    @Override
    public long getChildId(int groupPosition, int childPosition) {
        return childPosition;
    }

    @Override
    public boolean hasStableIds() {
        return false;
    }

    @Override
    public View getGroupView(final int groupPosition, boolean isExpanded, View convertView, ViewGroup parent) {
        final GroupViewHolder groupViewHolder;
        if (convertView == null) {
            convertView = View.inflate(mcontext, R.layout.item_shopcar_group, null);
            groupViewHolder = new GroupViewHolder(convertView);
            convertView.setTag(groupViewHolder);
        } else {
            groupViewHolder = (GroupViewHolder) convertView.getTag();
        }
        if (groups.size() != 0) {
            final StoreBean group = (StoreBean) getGroup(groupPosition);
            groupViewHolder.tvShopName.setText(group.getName());
            groupViewHolder.storeCheckBox.setOnClickListener(new View.OnClickListener() {
                @Override
                public void onClick(View v) {
                    group.setChecked(((CheckBox) v).isChecked());
                    checkInterface.checkGroup(groupPosition, ((CheckBox) v).isChecked());
                }
            });
            groupViewHolder.storeCheckBox.setChecked(group.isChecked());

        } else {
            groupViewHolder.llTitle.setVisibility(View.GONE);
        }
        return convertView;
    }

    @Override
    public View getChildView(final int groupPosition, final int childPosition, boolean isLastChild, View convertView, ViewGroup parent) {
        final ChildViewHolder childViewHolder;
        if (convertView == null) {
            convertView = View.inflate(mcontext, R.layout.item_shopcar_product, null);
            childViewHolder = new ChildViewHolder(convertView);
            convertView.setTag(childViewHolder);
        } else {
            childViewHolder = (ChildViewHolder) convertView.getTag();
        }
        if (groups.size() != 0) {
            final MultiGoodsBean child = (MultiGoodsBean) getChild(groupPosition, childPosition);
            if (child != null) {
                childViewHolder.tvGoodsName.setText(child.getName());
                childViewHolder.tvMoney.setText("￥" + child.getMoney());
                childViewHolder.tvNumber.setText(child.getNum() + "");
                childViewHolder.singleCheckBox.setChecked(child.isChecked());


                childViewHolder.singleCheckBox.setOnClickListener(new View.OnClickListener() {
                    @Override
                    public void onClick(View v) {
                        child.setChecked(((CheckBox) v).isChecked());
                        childViewHolder.singleCheckBox.setChecked(((CheckBox) v).isChecked());
                        checkInterface.checkChild(groupPosition, childPosition, ((CheckBox) v).isChecked());
                    }
                });
                childViewHolder.ivAdd.setOnClickListener(new View.OnClickListener() {
                    @Override
                    public void onClick(View v) {
                        modifyCountInterface.doIncrease(groupPosition, childPosition, childViewHolder.tvNumber, childViewHolder.singleCheckBox.isChecked());
                    }
                });
                childViewHolder.ivMinus.setOnClickListener(new View.OnClickListener() {
                    @Override
                    public void onClick(View v) {
                        modifyCountInterface.doDecrease(groupPosition, childPosition, childViewHolder.tvNumber, childViewHolder.singleCheckBox.isChecked());
                    }
                });

            }
        }else {
            childViewHolder.llTitleA.setVisibility(View.GONE);
        }
        return convertView;
    }

    @Override
    public boolean isChildSelectable(int groupPosition, int childPosition) {
        return true;
    }


    static class GroupViewHolder {
        CheckBox storeCheckBox;
        TextView tvDiscount;
        TextView tvShopName;
        LinearLayout llTitle;

        public GroupViewHolder(View view) {
            tvDiscount = view.findViewById(R.id.tv_discount);
            tvShopName = view.findViewById(R.id.tv_shop_name);
            storeCheckBox = view.findViewById(R.id.store_check_box);
            llTitle = view.findViewById(R.id.ll_title);
        }
    }

    static class ChildViewHolder {

        CheckBox singleCheckBox;
        RoundedImageView imageView;
        TextView tvGoodsName;
        TextView tvSpec;
        TextView tvMoney;
        ImageView ivMinus;
        TextView tvNumber;
        ImageView ivAdd;
        LinearLayout llTitleA;

        public ChildViewHolder(View view) {
            singleCheckBox = view.findViewById(R.id.single_check_box);
            imageView = view.findViewById(R.id.image_View);
            tvGoodsName = view.findViewById(R.id.tv_goods_name);
            tvSpec = view.findViewById(R.id.tv_spec);
            tvMoney = view.findViewById(R.id.tv_money);
            ivMinus = view.findViewById(R.id.iv_minus);
            tvNumber = view.findViewById(R.id.tv_number);
            ivAdd = view.findViewById(R.id.iv_add);
            llTitleA = view.findViewById(R.id.ll_title_a);
        }
    }



    public CheckInterface getCheckInterface() {
        return checkInterface;
    }

    public void setCheckInterface(CheckInterface checkInterface) {
        this.checkInterface = checkInterface;
    }

    public ModifyCountInterface getModifyCountInterface() {
        return modifyCountInterface;
    }

    public void setModifyCountInterface(ModifyCountInterface modifyCountInterface) {
        this.modifyCountInterface = modifyCountInterface;
    }

    /**
     * 店铺的复选框
     */
    public interface CheckInterface {
        /**
         * 组选框状态改变触发的事件
         *
         * @param groupPosition 组元素的位置
         * @param isChecked     组元素的选中与否
         */
        void checkGroup(int groupPosition, boolean isChecked);

        /**
         * 子选框状态改变触发的事件
         *
         * @param groupPosition 组元素的位置
         * @param childPosition 子元素的位置
         * @param isChecked     子元素的选中与否
         */
        void checkChild(int groupPosition, int childPosition, boolean isChecked);
    }


    /**
     * 改变数量的接口
     */
    public interface ModifyCountInterface {
        /**
         * 增加操作
         *
         * @param groupPosition 组元素的位置
         * @param childPosition 子元素的位置
         * @param showCountView 用于展示变化后数量的View
         * @param isChecked     子元素选中与否
         */
        void doIncrease(int groupPosition, int childPosition, View showCountView, boolean isChecked);

        void doDecrease(int groupPosition, int childPosition, View showCountView, boolean isChecked);

        void doUpdate(int groupPosition, int childPosition, View showCountView, boolean isChecked);

        /**
         * 删除子Item
         *
         * @param groupPosition
         * @param childPosition
         */
        void childDelete(int groupPosition, int childPosition);
    }

}

代码拿过来就可以使用，测试多次确保无误。

源码地址

如有问题，请直接联系我。