无法将片段添加到片段管理器

Question

import androidx.appcompat.app.AppCompatActivity;
import androidx.fragment.app.Fragment;
import androidx.fragment.app.FragmentManager; 

Fragment fragmentHome, fragmentHome2;
FragmentManager fragmentManager;

private void setFragments() {
            fragmentHome = new HomeFragment();
            fragmentHome2 = new HomeFragment();
            fragmentManager = getSupportFragmentManager();

            fragmentManager.beginTransaction().add(R.id.main_fragment_frame, fragmentHome).commit();
            fragmentManager.beginTransaction().add(R.id.main_fragment_frame, fragmentHome2).commit();
            Log.d(TAG, "added just ago: " + fragmentManager.getFragments().toString());
            Log.d(TAG, "added size: " + fragmentManager.getFragments().size()+"");
    }

但结果是：D/MainActivity: added just ago: [] D/MainActivity: added size: 0

为什么？？我的代码有问题吗？

Answer 1

你的代码没有问题。一开始，会得到 empty。但是在另一个代码中，这将导致 没有片段 。我使用 BottomNavigationView。你应该在其他代码中写日志。

BottomNavigationView bottomnavigationview = findViewById(R.id.nav_view);
bottomnavigationview.setOnNavigationItemSelectedListener(menuItem -> {
switch (menuItem.getItemId()){
   case R.id.navigation_home:
         // This will result all fragments and size.
         Log.d("Fragments ",fragmentManager.getFragments()+"" + fragmentManager.getFragments().size());
         return true;
........//your code
}

}

无法将片段添加到片段管理器

cannot add fragment to fragmentManager

android

fragment