实现在fragment中填入组件

MainActivity：

package com.example.myapplication;

import androidx.appcompat.app.AppCompatActivity;
import androidx.navigation.NavController;
import androidx.navigation.Navigation;
import androidx.navigation.fragment.NavHostFragment;
import androidx.navigation.ui.AppBarConfiguration;
import androidx.navigation.ui.NavigationUI;

import android.annotation.SuppressLint;
import android.graphics.Color;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;

import com.google.android.material.bottomnavigation.BottomNavigationItemView;
import com.google.android.material.bottomnavigation.BottomNavigationView;

public class MainActivity extends AppCompatActivity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        @SuppressLint({"MissingInflatedId", "LocalSuppress"})
        BottomNavigationView bottomNavigationView = findViewById(R.id.bottomnavigation);
//        NavController navController = Navigation.findNavController(this, R.id.fragment);
        NavHostFragment navHostFragment = (NavHostFragment) getSupportFragmentManager().findFragmentById(R.id.fragment);
        NavController navController = navHostFragment.getNavController();
        AppBarConfiguration configuration = new AppBarConfiguration.Builder(bottomNavigationView.getMenu()).build();
        NavigationUI.setupActionBarWithNavController(this, navController, configuration);
        NavigationUI.setupWithNavController(bottomNavigationView, navController);
    }

}