This is the recommended (e.g., by Josh Bloch, [Effective Java item 4](http://books.google.de/books?id=ka2VUBqHiWkC&pg=PA19&lpg=PA19&dq=private+constructor+%22throw+new+AssertionError%22&source=bl&ots=yYLfQfv-P-&sig=qL5J3mlURs4PwkMVJzy-pOnSK_g&hl=en&sa=X&ei=uTPmUr6VLIfn4gSEyIGgCw&ved=0CEIQ6AEwAw#v=onepage&q=private%20constructor%20%22throw%20new%20AssertionError%22&f=false)) pattern for utility (non-)classes that only provide static methods (like, e.h., `java.util.Collections`)