findFragmentById always returns null

Question

I\'m defining an ID for my fragment in the xml layout:

Answer 1

FragmentB fragmentB = 
(FragmentB) getSupportFragmentManager().findFragmentById(R.id.containerb);

if(fragmentB != null)
{
   fragmentB.showuserResponse(msg);
}

Use container id as fragment id. And then check for null reference.