Android studio MainActivity转为Fragment中mContext

Question

如题，用了单独的购物车项目，MainActivity转为Fragment，但是代码报错，mContext

package com.example.myapplication.ui.cart.adapter;

import android.view.View;
import android.widget.ImageView;

import androidx.annotation.Nullable;

import com.bumptech.glide.Glide;
import com.chad.library.adapter.base.BaseQuickAdapter;

import com.chad.library.adapter.base.viewholder.BaseViewHolder;
import com.example.myapplication.ui.cart.bean.CarResponse;
import com.example.myapplication.R;

import com.example.myapplication.ui.cart.CartFragment;
import java.util.List;

/**
 * 商品适配器
 *
 * @author llw
 */
public class GoodsAdapter extends BaseQuickAdapter<CarResponse.OrderDataBean.CartlistBean, BaseViewHolder> {

    public GoodsAdapter(int layoutResId, @Nullable List<CarResponse.OrderDataBean.CartlistBean> data) {
        super(layoutResId, data);
    }

    @Override
    protected void convert(BaseViewHolder helper, CarResponse.OrderDataBean.CartlistBean item) {
        helper.setText(R.id.tv_good_name, item.getProductName())
                .setText(R.id.tv_good_color, item.getColor())
                .setText(R.id.tv_good_size, item.getSize())
                .setText(R.id.tv_goods_price, item.getPrice() + "")
                .setText(R.id.tv_goods_num, item.getCount() + "");
        ImageView goodImg = helper.getView(R.id.iv_goods);
        Glide.with(mContext).load(item.getDefaultPic()).into(goodImg);

        ImageView checkedGoods = helper.getView(R.id.iv_checked_goods);
        //判断商品是否选中
        if (item.isChecked()) {
            checkedGoods.setImageDrawable(mContext.getDrawable(R.drawable.ic_checked));
        } else {
            checkedGoods.setImageDrawable(mContext.getDrawable(R.drawable.ic_check));
        }
        //添加点击事件
        helper.addOnClickListener(R.id.iv_checked_goods)//选中商品
                .addOnClickListener(R.id.tv_increase_goods_num)//增加商品
                .addOnClickListener(R.id.tv_reduce_goods_num);//减少商品
    }
}

以及Fragment部分

package com.example.myapplication.ui.cart;

import androidx.annotation.NonNull;
import androidx.appcompat.app.AlertDialog;
import androidx.appcompat.app.AppCompatActivity;
import androidx.fragment.app.Fragment;
import androidx.recyclerview.widget.LinearLayoutManager;
import androidx.recyclerview.widget.RecyclerView;

import android.annotation.SuppressLint;
import android.content.Context;
import android.content.DialogInterface;
import android.os.Bundle;
import android.util.Log;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ImageView;
import android.widget.LinearLayout;
import android.widget.TextView;
import android.widget.Toast;

import com.chad.library.adapter.base.BaseQuickAdapter;
import com.google.gson.Gson;
import com.example.myapplication.ui.cart.adapter.StoreAdapter;
import com.example.myapplication.ui.cart.bean.CarResponse;
import com.example.myapplication.ui.cart.util.Constant;
import com.example.myapplication.ui.cart.util.GoodsCallback;
import com.scwang.smartrefresh.layout.SmartRefreshLayout;
import com.scwang.smartrefresh.layout.api.RefreshLayout;
import com.scwang.smartrefresh.layout.listener.OnRefreshListener;

import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

import com.example.myapplication.R;

import org.jetbrains.annotations.NotNull;

/**
 * 购物车
 *
 * @author llw
 */
public class CartFragment extends Fragment implements GoodsCallback, View.OnClickListener {

    public static final String TAG = "MainActivity";

    private RecyclerView rvStore;
    private StoreAdapter storeAdapter;
    private List<CarResponse.OrderDataBean> mList = new ArrayList<>();
    private TextView tvEdit;//编辑
    private ImageView ivCheckedAll;//全选
    private TextView tvTotal;//合计价格
    private TextView tvSettlement;//结算
    private LinearLayout layEdit;//编辑底部布局
    private TextView tvShareGoods;//分享商品
    private TextView tvCollectGoods;//收藏商品
    private TextView tvDeleteGoods;//删除商品

    private boolean isEdit = false;//是否编辑
    private boolean isAllChecked = false;//是否全选

    private List<Integer> shopIdList = new ArrayList<>();//店铺列表

    private double totalPrice = 0.00;//商品总价
    private int totalCount = 0;//商品总数量

    private AlertDialog dialog;//弹窗

    private boolean isHaveGoods = false;//购物车是否有商品

    private SmartRefreshLayout refresh;//刷新布局
    private LinearLayout layEmpty;//空布局


    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
        View view = View.inflate(getActivity(), R.layout.fragment_cart,null);
        //setContentView(R.layout.activity_main);

        //设置亮色状态栏模式 systemUiVisibility在Android11中弃用了，可以尝试一下。
        requireActivity().getWindow().getDecorView().setSystemUiVisibility(View.SYSTEM_UI_FLAG_LAYOUT_FULLSCREEN | View.SYSTEM_UI_FLAG_LIGHT_STATUS_BAR);

        rvStore = view.findViewById(R.id.rv_store);
        tvEdit = view.findViewById(R.id.tv_edit);
        ivCheckedAll = view.findViewById(R.id.iv_checked_all);
        tvTotal = view.findViewById(R.id.tv_total);
        tvSettlement = view.findViewById(R.id.tv_settlement);
        layEdit = view.findViewById(R.id.lay_edit);
        tvShareGoods = view.findViewById(R.id.tv_share_goods);
        tvCollectGoods = view.findViewById(R.id.tv_collect_goods);
        tvDeleteGoods = view.findViewById(R.id.tv_delete_goods);
        refresh = view.findViewById(R.id.refresh);
        layEmpty = view.findViewById(R.id.lay_empty);
        //禁用下拉刷新和上拉加载更多
        refresh.setEnableRefresh(false);
        refresh.setEnableLoadMore(false);
        //下拉刷新监听
        refresh.setOnRefreshListener(refreshLayout -> initView());

        tvEdit.setOnClickListener(this);
        ivCheckedAll.setOnClickListener(this);
        tvSettlement.setOnClickListener(this);
        tvShareGoods.setOnClickListener(this);
        tvCollectGoods.setOnClickListener(this);
        tvDeleteGoods.setOnClickListener(this);

        CarResponse carResponse = new Gson().fromJson(Constant.CAR_JSON, CarResponse.class);

        mList.addAll(carResponse.getOrderData());
        storeAdapter = new StoreAdapter(R.layout.item_store, mList, this);
        rvStore.setLayoutManager(new LinearLayoutManager(getActivity()));
        rvStore.setAdapter(storeAdapter);
        //店铺点击

        storeAdapter.setOnItemChildClickListener(new BaseQuickAdapter.OnItemChildClickListener() {
            @Override
            public void onItemChildClick(BaseQuickAdapter adapter, View view, int position) {
                CarResponse.OrderDataBean storeBean = mList.get(position);
                if (view.getId() == R.id.iv_checked_store) {
                    storeBean.setChecked(!storeBean.isChecked());
                    storeAdapter.notifyDataSetChanged();
                    //传递选中店铺的id
                    if (storeBean.isChecked()) {
                        //全选商品
                        storeAdapter.controlGoods(storeBean.getShopId(), true);

                        //添加到列表中
                        if (!shopIdList.contains(storeBean.getShopId())) {
                            //如果列表中没有这个店铺Id且当前店铺为选中状态
                            shopIdList.add(storeBean.getShopId());
                        }
                    } else {
                        //清除全选商品
                        storeAdapter.controlGoods(storeBean.getShopId(), false);

                        //从列表中清除
                        if (shopIdList.contains(storeBean.getShopId())) {
                            shopIdList.remove((Integer) storeBean.getShopId());
                        }
                    }
                    //控制页面全选
                    controlAllChecked();
                }
            }
        });
        //有商品
        isHaveGoods = true;
        //下拉加载数据完成后，关闭下拉刷新动画
        refresh.finishRefresh();
        //隐藏布局
        layEmpty.setVisibility(View.GONE);
        return view;
    }

    /**
     * 初始化
     */
    private void initView() {

    }

    /**
     * 控制页面全选   与页面全选进行交互
     */
    private void controlAllChecked() {
        if (shopIdList.size() == mList.size() && mList.size() != 0) {
            //全选
            ivCheckedAll.setImageDrawable(getResources().getDrawable(R.drawable.ic_checked));
            isAllChecked = true;
        } else {
            //不全选
            ivCheckedAll.setImageDrawable(getResources().getDrawable(R.drawable.ic_check));
            isAllChecked = false;
        }
        //计算价格
        calculationPrice();
    }

    /**
     * 选中店铺
     *
     * @param shopId 店铺id
     */
    @Override
    public void checkedStore(int shopId, boolean state) {
        for (CarResponse.OrderDataBean bean : mList) {
            //遍历
            if (shopId == bean.getShopId()) {
                bean.setChecked(state);
                storeAdapter.notifyDataSetChanged();
                //记录选中店铺的shopid,添加到一个列表中。
                if (!shopIdList.contains(bean.getShopId()) && state) {
                    //如果列表中没有这个店铺Id且当前店铺为选中状态
                    shopIdList.add(bean.getShopId());
                } else {
                    if (shopIdList.contains(bean.getShopId())) {
                        //通过list.indexOf获取属性的在列表中的下标，不过强转Integer更简洁
                        shopIdList.remove((Integer) bean.getShopId());
                    }
                }
            }
        }
        //控制页面全选
        controlAllChecked();
    }


    /**
     * 商品价格
     */
    @Override
    public void calculationPrice() {
        //每次计算之前先置零
        totalPrice = 0.00;
        totalCount = 0;
        //循环购物车中的店铺列表
        for (int i = 0; i < mList.size(); i++) {
            CarResponse.OrderDataBean orderDataBean = mList.get(i);
            //循环店铺中的商品列表
            for (int j = 0; j < orderDataBean.getCartlist().size(); j++) {
                CarResponse.OrderDataBean.CartlistBean cartlistBean = orderDataBean.getCartlist().get(j);
                //当有选中商品时计算数量和价格
                if (cartlistBean.isChecked()) {
                    totalCount++;
                    totalPrice += cartlistBean.getPrice() * cartlistBean.getCount();
                }
            }
        }
        tvTotal.setText("￥" + totalPrice);
        tvSettlement.setText(totalCount == 0 ? "结算" : "结算(" + totalCount + ")");
    }

    /**
     * 页面控件点击事件
     *
     * @param v
     */
    @Override
    public void onClick(View v) {
        switch (v.getId()) {
            case R.id.tv_edit://编辑
                if (!isHaveGoods) {
                    showMsg("当前购物车空空如也~");
                    return;
                }
                if (isEdit) {
                    tvEdit.setText("编辑");
                    layEdit.setVisibility(View.GONE);
                    isEdit = false;
                } else {
                    tvEdit.setText("完成");
                    layEdit.setVisibility(View.VISIBLE);
                    isEdit = true;
                }
                break;
            case R.id.iv_checked_all://全选
                if (!isHaveGoods) {
                    showMsg("当前购物车空空如也~");
                    return;
                }
                if (isAllChecked) {
                    //取消全选
                    isSelectAllStore(false);
                } else {
                    //全选
                    isSelectAllStore(true);
                }
                break;
            case R.id.tv_settlement://结算
                if (!isHaveGoods) {
                    showMsg("当前购物车空空如也~");
                    return;
                }
                if (totalCount == 0) {
                    showMsg("请选择要结算的商品");
                    return;
                }
                //弹窗
                dialog = new AlertDialog.Builder(getActivity())
                        .setMessage("总计:" + totalCount + "种商品，" + totalPrice + "元")
                        .setPositiveButton("确定", (dialog, which) -> deleteGoods())
                        .setNegativeButton("取消", (dialog, which) -> dialog.dismiss())
                        .create();
                dialog.show();
                break;
            case R.id.tv_delete_goods://删除
                if (totalCount == 0) {
                    showMsg("请选择要删除的商品");
                    return;
                }
                //弹窗
                dialog = new AlertDialog.Builder(getActivity())
                        .setMessage("确定要删除所选商品吗?")
                        .setPositiveButton("确定", (dialog, which) -> deleteGoods())
                        .setNegativeButton("取消", (dialog, which) -> dialog.dismiss())
                        .create();
                dialog.show();
                break;
            case R.id.tv_collect_goods://收藏
                if (totalCount == 0) {
                    showMsg("请选择要收藏的商品");
                    return;
                }
                showMsg("收藏成功!");
                break;
            case R.id.tv_share_goods://分享
                if (totalCount == 0) {
                    showMsg("请选择要分享的商品");
                    return;
                }
                showMsg("分享成功!");
                break;
            default:
                break;
        }
    }

    /**
     * 删除商品
     */
    private void deleteGoods() {
        //店铺列表
        List<CarResponse.OrderDataBean> storeList = new ArrayList<>();

        for (int i = 0; i < mList.size(); i++) {
            CarResponse.OrderDataBean store = mList.get(i);
            if (store.isChecked()) {
                //店铺如果选择则添加到此列表中
                storeList.add(store);
            }
            //商品列表
            List<CarResponse.OrderDataBean.CartlistBean> goodsList = new ArrayList<>();

            List<CarResponse.OrderDataBean.CartlistBean> goods = store.getCartlist();
            //循环店铺中的商品列表
            for (int j = 0; j < goods.size(); j++) {
                CarResponse.OrderDataBean.CartlistBean cartlistBean = goods.get(j);
                //当有选中商品时添加到此列表中
                if (cartlistBean.isChecked()) {
                    goodsList.add(cartlistBean);
                }
            }
            //删除商品
            goods.removeAll(goodsList);
        }
        //删除店铺
        mList.removeAll(storeList);

        shopIdList.clear();//删除了选中商品，清空已选择的标识
        controlAllChecked();//控制去全选
        //改变界面UI
        tvEdit.setText("编辑");
        layEdit.setVisibility(View.GONE);
        isEdit = false;
        //刷新数据
        storeAdapter.notifyDataSetChanged();
        if (mList.size() <= 0) {
            //无商品
            isHaveGoods = false;
            //启用下拉刷新
            refresh.setEnableRefresh(true);
            //显示空布局
            layEmpty.setVisibility(View.VISIBLE);
        }
    }

    /**
     * 是否全选
     *
     * @param state 状态
     */
    private void isSelectAllStore(boolean state) {
        //修改背景
        ivCheckedAll.setImageDrawable(getResources().getDrawable(state ? R.drawable.ic_checked : R.drawable.ic_check));

        for (CarResponse.OrderDataBean orderDataBean : mList) {
            //商品是否选中
            storeAdapter.controlGoods(orderDataBean.getShopId(), state);
            //店铺是否选中
            checkedStore(orderDataBean.getShopId(), state);
        }
        isAllChecked = state;
    }

    /**
     * Toast提示
     *
     * @param msg
     */
    private void showMsg(String msg) {
        Toast.makeText(getActivity(), msg, Toast.LENGTH_SHORT).show();
    }
    @Override

    public void onAttach(@NotNull Context context) {
        Context mContext=null;
        super.onAttach(context);
        //searchMainContent = ((SearchMainActivity) context).getFilmSearchContent();
    }
}

Answer 1

BaseQuickAdapter用的哪个版本，有的版本是mContext，有的版本直接就是context