片段不会替换，当我点击底部导航

Question

为什么当我点击项目导航视图片段时不能替换内容。

navigation = (BottomNavigationView) findViewById(R.id.navigation); 
navigation.setOnNavigationItemReselectedListener(new BottomNavigationView.OnNavigationItemReselectedListener() { 
    @Override 
    public void onNavigationItemReselected(@NonNull MenuItem item) { 
    int id = item.getItemId(); 
    if (id == R.id.navigation_home) { 
     fragment = new HomeFragment(); 
    } else if (id == R.id.navigation_dashboard) { 
     fragment = new PopularFragment(); 
    } else if (id == R.id.navigation_notifications) { 
     fragment = new FeaturedFragment(); 
    } 
    FragmentTransaction transaction = fragmentManager.beginTransaction(); 
    transaction.replace(R.id.content, fragment); 
    transaction.commit(); 
    } 

}); 

}

Answer 1

使用下面的代码在android.support.v4

FragmentTransaction ft = getFragmentManager().beginTransaction(); 
DemoFragment w1 = new DemoFragment(); 
ft.addToBackStack(""); 
ft.replace(R.id.listFragment, w1); 
ft.commit();