Android Studio(Java)：切换两个Fragment不重建方案失效？

我尝试让Android应用切换Fragment时保留用户在Fragment内的操作，要求切换时不重建或替换Fragment，仅通过显示/隐藏实现。比如在Fragment1勾选复选框后切换到Fragment2，再切回Fragment1时复选框仍保持勾选状态。参考相关方案后未能正常工作：从HomeFragment切换到WidgetFragment时，WidgetFragment会叠加在HomeFragment之上。

HomeFragment显示效果：

切换到WidgetFragment后的效果：

WidgetFragment的TextView和复选框叠加在HomeFragment内容上方

代码示例 #

package loon.si.weather_app;

import androidx.annotation.NonNull;
import androidx.appcompat.app.ActionBarDrawerToggle;
import androidx.appcompat.app.AppCompatActivity;
import androidx.appcompat.widget.Toolbar;
import androidx.core.view.GravityCompat;
import androidx.drawerlayout.widget.DrawerLayout;
import androidx.fragment.app.FragmentManager;
import android.annotation.SuppressLint;
import android.os.Bundle;
import android.view.MenuItem;

import com.google.android.material.navigation.NavigationView;

import java.util.Objects;

public class MainActivity extends AppCompatActivity implements NavigationView.OnNavigationItemSelectedListener {
    
    private DrawerLayout drawerLayout;

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

        Toolbar toolbar = findViewById(R.id.toolbar);
        setSupportActionBar(toolbar);
        
        drawerLayout = findViewById(R.id.drawer_layout);
        NavigationView navigationView = findViewById(R.id.nav_view);
        navigationView.setNavigationItemSelectedListener(this);

        ActionBarDrawerToggle toggle = new ActionBarDrawerToggle(this, drawerLayout, toolbar, R.string.open_nav, R.string.close_nav);

        drawerLayout.addDrawerListener(toggle);
        toggle.syncState();

        if (savedInstanceState == null) {
            getSupportFragmentManager().beginTransaction()
                    .replace(R.id.fragment_container, new HomeFragment()).commit();
            navigationView.setCheckedItem(R.id.nav_home);
        }

    }

    @Override
    public void onDestroy() {
        super.onDestroy();
        FragmentManager fragmentManager = getSupportFragmentManager();
        if(fragmentManager.findFragmentById(R.id.nav_home) != null){
            fragmentManager.beginTransaction().remove(Objects.requireNonNull(fragmentManager.findFragmentById(R.id.nav_home))).commit();
        }
        if(fragmentManager.findFragmentById(R.id.nav_widget) != null){
            fragmentManager.beginTransaction().remove(Objects.requireNonNull(fragmentManager.findFragmentById(R.id.nav_widget))).commit();
        }
    }

    @SuppressLint("NonConstantResourceId")
    @Override
    public boolean onNavigationItemSelected(@NonNull MenuItem item) {
        FragmentManager fragmentManager = getSupportFragmentManager();
        switch (item.getItemId()){
            case R.id.nav_home:
                if(fragmentManager.findFragmentById(R.id.nav_home) != null) {
                    //if the fragment exists, show it.
                    fragmentManager.beginTransaction().show(Objects.requireNonNull(fragmentManager.findFragmentById(R.id.nav_home))).commit();
                } else {
                    //if the fragment does not exist, add it to fragment manager.
                    fragmentManager.beginTransaction().add(R.id.fragment_container, new HomeFragment(), "home").commit();
                }
                if(fragmentManager.findFragmentById(R.id.nav_widget) != null){
                    //if the other fragment is visible, hide it.
                    fragmentManager.beginTransaction().hide(Objects.requireNonNull(fragmentManager.findFragmentById(R.id.nav_widget))).commit();
                }
                break;

            case R.id.nav_widget:
                if(fragmentManager.findFragmentById(R.id.nav_widget) != null) {
                    //if the fragment exists, show it.
                    fragmentManager.beginTransaction().show(Objects.requireNonNull(fragmentManager.findFragmentById(R.id.nav_widget))).commit();
                } else {
                    //if the fragment does not exist, add it to fragment manager.
                    fragmentManager.beginTransaction().add(R.id.fragment_container, new WidgetFragment(), "widget").commit();
                }
                if(fragmentManager.findFragmentById(R.id.nav_home) != null){
                    //if the other fragment is visible, hide it.
                    fragmentManager.beginTransaction().hide(Objects.requireNonNull(fragmentManager.findFragmentById(R.id.nav_home))).commit();
                }
                break;
        }
        drawerLayout.closeDrawer(GravityCompat.START);
        return true;
    }

    @Override
    public void onBackPressed() {
        if (drawerLayout.isDrawerOpen(GravityCompat.START)){
            drawerLayout.closeDrawer(GravityCompat.START);
        } else {
            super.onBackPressed();
        }
    }
}

内容的提问来源于stack exchange，提问作者johndo19