addToBackStack（）与getChildFragmentManager（）不兼容

Question

按下返回按钮后，单击按钮时显示的新片段没有关闭，而是关闭了整个应用程序。该按钮位于三个选项卡之一中。下面提到mainActivity.java的代码，HeroesFragment（具有三个选项卡的片段），StrengthHeroesFragment（具有按钮的三个选项卡之一）。

MainActivity.java

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


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

    Toolbar toolbar=findViewById(R.id.toolbar);
    setSupportActionBar(toolbar);

    drawer=findViewById(R.id.draw_layout);
    NavigationView navigationView=findViewById(R.id.nav_view);
    navigationView.setNavigationItemSelectedListener(this);

    ActionBarDrawerToggle toggle=new ActionBarDrawerToggle(this,drawer,toolbar,
            R.string.navigation_drawer_open,R.string.navigation_drawer_close);

    drawer.addDrawerListener(toggle);
    toggle.syncState();

    if (savedInstanceState==null){
    getSupportFragmentManager().beginTransaction().replace(R.id.fragment_container,new HeroesFragment()).commit();

    navigationView.setCheckedItem(R.id.nav_heroes);}

}

@Override
public boolean onNavigationItemSelected(@NonNull MenuItem item) {
    switch (item.getItemId()){
        case R.id.nav_heroes:
            getSupportFragmentManager().beginTransaction().replace(R.id.fragment_container,new HeroesFragment()).commit();
            break;
        case R.id.nav_items:
            getSupportFragmentManager().beginTransaction().replace(R.id.fragment_container,new ItemsFragment()).commit();
            break;
        case R.id.nav_counterpicker:
            getSupportFragmentManager().beginTransaction().replace(R.id.fragment_container,new CounterPickerFragment()).commit();
            break;
        case R.id.nav_news:
            getSupportFragmentManager().beginTransaction().replace(R.id.fragment_container,new NewsFragment()).commit();
            break;

    }

    drawer.closeDrawer(GravityCompat.START);
    return true;
}

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


}

}

HeroesFragment.java（包含三个选项卡的片段）

public class HeroesFragment extends Fragment {


private TabLayout tabLayout;
private AppBarLayout appBarLayout;
private ViewPager viewPager;
View view;
RelativeLayout relativeLayout;

@Nullable
@Override
public View onCreateView(@NonNull LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {
    view= inflater.inflate(R.layout.fragment_heroes,container,false);

    relativeLayout=(RelativeLayout)view.findViewById(R.id.hero_layout);
    tabLayout=(TabLayout)view.findViewById(R.id.heroes_tablayout);
    appBarLayout=(AppBarLayout)view.findViewById(R.id.hero_appbar);
    viewPager=(ViewPager)view.findViewById(R.id.heroes_viewpager);
    ViewPageAdapter adapter=new ViewPageAdapter(getChildFragmentManager(),1);
    adapter.AddFragment(new StrengthHeroesFragment(),"Strength" );
    adapter.AddFragment(new AgilityHeroesFragment(),"Agility");
    adapter.AddFragment(new IntelligenceHeroesFragment(),"Intelligence");
    viewPager.addOnPageChangeListener(new TabLayout.TabLayoutOnPageChangeListener(tabLayout));
    tabLayout.addTab(tabLayout.newTab().setText("Tab 1"));

    tabLayout.addOnTabSelectedListener(new TabLayout.OnTabSelectedListener() {
        @Override
        public void onTabSelected(TabLayout.Tab tab) {
            switch (tab.getPosition()){
                case 0:
                    Toast.makeText(getContext(),"Tab 1",Toast.LENGTH_SHORT).show();
                    break;

                case 1:
                    Toast.makeText(getContext(),"Tab 2",Toast.LENGTH_SHORT).show();
                    break;
                case 2:
                    Toast.makeText(getContext(),"tab 3",Toast.LENGTH_SHORT).show();
                    break;
                default:
                    break;
            }

        }

        @Override
        public void onTabUnselected(TabLayout.Tab tab) {

        }

        @Override
        public void onTabReselected(TabLayout.Tab tab) {

        }
    });

    viewPager.setAdapter(adapter);
    tabLayout.setupWithViewPager(viewPager);

    return view;


}



}

StrengthHeroesFragment.java（包含按钮的片段）

public class StrengthHeroesFragment extends Fragment {

View view;
ImageButton ib1,ib2,ib3,ib4,ib5,ib6;
TextView t1,t2,t3,t4,t5,t6;


public View onCreateView(@NonNull LayoutInflater inflater, @Nullable ViewGroup container, @Nullable 
Bundle savedInstanceState) {

    view=inflater.inflate(R.layout.fragment_strength_heroes,container,false);


    ib1=(ImageButton)view.findViewById(R.id.abaddon_icon);


   ib1.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            HeroDetailsFragment heroDetailsFragment=new HeroDetailsFragment();

            Bundle data=new Bundle();
            data.putString("heroname","Abaddon");
            heroDetailsFragment.setArguments(data);
            FragmentTransaction transaction=getChildFragmentManager().beginTransaction();
            transaction.replace(R.id.strength_hero_layout,heroDetailsFragment).addToBackStack(null);
            transaction.commit();
        }
    });
return view;
}


}

当我在StrengthHeroes片段中使用getFragmentManager（）而不是getChildFragmentManager（）时，它实际上可以工作，但是当我切换到导航抽屉中的另一个片段时，选项卡布局片段中的内容就消失了。我还尝试使用setPrimaryNavigationFragment（）仍然无法正常工作。请帮助我.....在此先感谢。

Answer 1

@Override
public void onBackPressed() {
    if (drawer.isDrawerOpen(GravityCompat.START)){
        drawer.closeDrawer(GravityCompat.START);
    }
    else{
     getSupportFragmentManager().popBackStack();

    }
}