Android Studio导航抽屉碎片重叠

Question

我已经在我的项目中添加了一个导航抽屉活动，并尝试将项目作为片段添加。这就是我在主要活动中所做的。

fragmentManager = getSupportFragmentManager();
        fragmentTransaction = fragmentManager.beginTransaction();
        fragmentTransaction.add(R.id.nav_host_fragment, new HomeFragment());
        fragmentTransaction.commit();

        navigationView.setNavigationItemSelectedListener(new NavigationView.OnNavigationItemSelectedListener() {
            @Override
           public boolean onNavigationItemSelected(@NonNull MenuItem item)
            {
                DrawerLayout drawer = (DrawerLayout) findViewById(R.id.drawer_layout);
                drawer.closeDrawer(GravityCompat.START);
                int id = item.getItemId();
                if (id == R.id.nav_home)
                {
                    fragmentManager = getSupportFragmentManager();
                    fragmentTransaction = fragmentManager.beginTransaction();
                    fragmentTransaction.replace(R.id.nav_host_fragment, new HomeFragment());
                    fragmentTransaction.commit();

                }
                else if(id == R.id.Shopping_list)
                {
                    fragmentManager = getSupportFragmentManager();
                    fragmentTransaction = fragmentManager.beginTransaction();
                    fragmentTransaction.replace(R.id.nav_host_fragment, new ShoppingListFragment());
                    fragmentTransaction.commit();
                }
                else if(id == R.id.nav_Language)
                {
                    fragmentManager = getSupportFragmentManager();
                    fragmentTransaction = fragmentManager.beginTransaction();
                    fragmentTransaction.replace(R.id.nav_host_fragment, new FragmentLang());
                    fragmentTransaction.commit();
                }

默认片段是Home，它工作正常，正如预期的那样，但其他片段与Home片段重叠。（HomeFragment是唯一工作正常的）。我在每个片段类中都做过这样的事情：

public class ShoppingListFragment extends Fragment{
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState){
   View view = inflater.inflate(R.layout.fragment_shopping_list, container,false);
   return view;
    }

}

我看不出错误在哪里。一切看起来都很好，但所有其他片段都显示在HomeFragment上。

Answer 1

片段管理器维护所有先前被替换片段的堆栈有时后堆栈片段与我们替换的片段重叠，添加此行

fragmentManager.popBackStack(); 

这样地，

fragmentManager = getSupportFragmentManager();
fragmentTransaction = fragmentManager.beginTransaction();
fragmentTransaction.replace(R.id.nav_host_fragment, new HomeFragment());
fragmentManager.popBackStack();
fragmentTransaction.commit();

        

希望会有所帮助。快乐编码：）