I have been using the v23.0.1 support library until now with no problems. Now when I switch to the new v23.1.0 library I am getting a null
With the design library v 23.1.0 the NavigationView works with a RecyclerView.
Also the Header is now a type of row.
It means that the header could not be immediately available in the view hierarchy.
It can cause issues if you are using methods like navigationView.findViewById(XXX) to get a view inside the header.
There is a bug in the Google Tracker.
EDIT 12/10/2015: Design library 23.1.1
The 23.1.1 introduces a new API for retrieving header views for NavigationView with getHeaderView()
BEFORE 23.1.1
workaround fot 23.1.0 can be to use a addOnLayoutChangeListener. Somenthing like:
navigationView.addOnLayoutChangeListener( new View.OnLayoutChangeListener()
{
@Override
public void onLayoutChange( ... )
{
navigationView.removeOnLayoutChangeListener( this );
View view = navigationView.findViewById( ... );
}
} );
Another possible workaround are:
remove the app:headerLayout attribute from the xml, and then add the header programatically.
Inflate the headerView programmatically.
Use somenthing like this:
View headerLayout = navigationView.inflateHeaderView(R.layout.navigation_header);
headerLayout.findViewById(xxx);