我成功地实现了底部导航抽屉，并使用了片段。现在我可以从抽屉菜单切换片段。我这里的问题是，当我从抽屉菜单打开一个项目时（例如；关于开发者），当用户单击后退按钮时，它会关闭应用程序。相反，我希望用户从任何片段返回到主活动。帮我个忙，我没有多少经验。
这是我的密码；
如何使用带有自定义库的抽屉适配器（slidingrootnav-https://github.com/yarolegovich/slidingrootnav);

@Override
    public void onItemSelected(int position) {
        FragmentTransaction transaction = getSupportFragmentManager().beginTransaction();

        if (position == POS_DASHBOARD){

            slidingRootNav.closeMenu();
            transaction.addToBackStack(null);
            transaction.commit();

        }

        else if (position == POS_ABOUT_APP){
            ((CoordinatorLayout)findViewById(R.id.root_view)).removeAllViews();

            AboutAppFragment aboutApp = new AboutAppFragment();
            transaction.replace(R.id.container, aboutApp);

            slidingRootNav.closeMenu();
            transaction.addToBackStack(null);
            transaction.commit();

        }
        else if (position == POS_ABOUT_DEVELOPERS){
            ((CoordinatorLayout)findViewById(R.id.root_view)).removeAllViews();

            AboutDeveloper aboutDeveloper = new AboutDeveloper();
            transaction.replace(R.id.container, aboutDeveloper);

            slidingRootNav.closeMenu();
            transaction.addToBackStack(null);
            transaction.commit();

        }

    }

片段类

import android.os.Bundle;
import androidx.appcompat.widget.Toolbar;
import androidx.fragment.app.Fragment;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;

public class AboutDeveloper extends Fragment  {

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
        ViewGroup root = (ViewGroup) inflater.inflate(R.layout.fragment_about_developer,container, false);

        // Here I implemented a toolbar at the top for navigation purpose
        // but on clicking on the nav icon, the app closes, instead i want to return to the main activity

        Toolbar toolbar = root.findViewById(R.id.return_home);
        toolbar.setNavigationIcon(R.drawable.ic_baseline_arrow_back_24);
        toolbar.setTitle("About Developer");

        toolbar.setNavigationOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                getActivity().onBackPressed();
            }
        });
        return root;

    }

}