Setting hint text for search widget when used as part of menu

You can set hint text to searchview using the api setQueryHint (CharSequence hint)

SearchView searchView = (SearchView) menu.findItem(R.id.menu_search).getActionView();
searchView.setQueryHint("Query Hint");

Refer the documentation

This will make the ActionView search box always show, by default:

searchView.setIconifiedByDefault(false);

This tells the search box to always be expanded. Iconified means that you need to tap the icon to make the search box appear.