【领券联盟】创建Fragment课程中，有一段报错，没找到原因，求解决办法

package com.stf.taobaounion.ui.activity;

import androidx.appcompat.app.AppCompatActivity;
import androidx.fragment.app.Fragment;
import androidx.fragment.app.FragmentManager;
import androidx.fragment.app.FragmentTransaction;

import android.os.Bundle;

import com.stf.taobaounion.R;
import com.stf.taobaounion.ui.fragment.HomeFragment;

public class MainActivity extends AppCompatActivity {


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

    private void initView() {
        HomeFragment homeFragment = new HomeFragment();
        FragmentManager fm = getSupportFragmentManager();
        FragmentTransaction transaction = fm.beginTransaction();

        //这一句报错，homeFragment报红线
        transaction.add(R.id.main_page_container, homeFragment);

        transaction.commit();

    }
}