在以下ShopFragment中按Back返回，设置RadioButton为选中状态，为什么会闪退？

Logcat说以下红色框处有空指针引用

com.testapp.tuangou.fragment;

android.os.Bundle;
android.view.LayoutInflater;
android.view.View;
android.view.ViewGroup;
android.widget.AdapterView;
android.widget.ListView;
android.widget.RadioButton;
android.widget.TextView;
android.widget.Toast;

androidx.fragment.app.Fragment;
androidx.fragment.app.FragmentTransaction;

com.testapp.tuangou.Food;
com.testapp.tuangou.Icon;
com.testapp.tuangou.MyAdapter;
com.testapp.tuangou.R;
com.testapp.tuangou.util.DataUtil;

java.util.ArrayList;

ShopFragment Fragment {
    String = ;
    ListView ;
    ArrayList<Food> = ;

    View onCreateView(LayoutInflater inflater, ViewGroup container,
                             Bundle savedInstanceState) {
        View view = inflater.inflate(R.layout., container, );

        initData();

        = view.findViewById(R.id.);

        MyAdapter<Food> lvAdapter = MyAdapter<Food>(, R.layout.) {
            bindView(ViewHolder holder, Food obj) {
                holder.setImageResource(R.id., obj.getIconId());
                holder.setText(R.id., obj.getName());
                holder.setText(R.id., obj.getFeature());
                holder.setText(R.id., +String.(obj.getPrice()));
                holder.setText(R.id., obj.getSpecial());
                holder.setText(R.id., +String.(obj.getSold()));
            }
        };
        .setAdapter(lvAdapter);

        .setOnItemClickListener(AdapterView.OnItemClickListener() {
            onItemClick(AdapterView<?> parent, View view, position, id) {
                Toast.(getContext(),.get(position).getName(),Toast.).show();
            }
        });

        view.findViewById(R.id.).setOnClickListener(View.OnClickListener() {
            onClick(View v) {
                getFragmentManager() != ;
                FragmentTransaction transaction = getFragmentManager().beginTransaction();
                transaction.replace(R.id.,IndexFragment());
                transaction.commit();
                RadioButton indexBtn = v.findViewById(R.id.);
                indexBtn.setChecked();
            }
        });
        view;
    }

    initData() {
        = ArrayList<Food>();
        (i = ; i < DataUtil..; i++) {
            .add(Food(DataUtil.[i], DataUtil.[i],
                    DataUtil.[i], DataUtil.[i], DataUtil.[i], DataUtil.[i]));
        }
    }
}