Android Api 23 Change Navigation View headerLayout textview

Orium answer works and this will work as well.

View header = navigationView.inflateHeaderView(R.layout.nav_header_main);
    TextView text = (TextView) header.findViewById(R.id.textView);
    texto.setText("HELLO");

I had the same issue and was able to avoid it with this code:

    View header = LayoutInflater.from(this).inflate(R.layout.nav_header_main, null);
    navigationView.addHeaderView(header);
    TextView text = (TextView) header.findViewById(R.id.textView);
    text.setText("HELLO");

Now with the 23.1.1 release of the design support library, you can use

View header = navigationView.getHeaderView(0)
TextView text = (TextView) header.findViewById(R.id.textView);